POSTER PRESENTATIONS

OPTICAL CHARACTERIZATION OF AN EDDY INDUCED DIATOM BLOOM IN THE LEE OF HAWAII

Nencioli, Francesco¹; Chang Spada, Grace¹; Twardowski, Michael<sup>2

1</sup>SEA Lab 5092 Rhoads ave. #a, Santa Barbara, CA, 93111, United States; ²Dep. of Research, WET Labs Inc., Narragansett, RI, 02882, United States

Optical measurements were collected during the E-FluxIII field experiment in the lee of Hawaii. The focus of the experiment was the cyclonic eddy Opal. Vertical profiles of chlorophyll fluorescence and beam attenuation at the center of the eddy show a relatively sharp Deep Chlorophyll Maximum, and broader peaks in beam transmission that extended to shallower depths. Microscopy of collected water samples revealed that the DCM was diatom dominated, and that the broader peak in beam transmission was due to a layer of unhealthy diatoms and empty frustules on top of the DCM. Here we investigate the relationship between scattering ratio (bbp/bp) and chlorophyll to attenuation coefficient ratio (Chl/cp) to optically characterize this interesting feature.

Our preliminary results show that an inverse relationship between bbp/bp and Chl/cp, also reported by others, is respected only up to the DCM. There, Chl/cp increases whereas bbp/bp remains similar to values found in the empty frustule layer. We hypothesize that this is the result of a packaging effect, i.e. frustule concentrations in the two layers are similar; however chlorophyll concentrations within the DCM with diatoms increases, therefore we observe progressively higher values of Chl/Cp for constant values of bbp/bp.

Increased values of both ratios are observed below the DCM. Vertical profiles of chlorophyll and attenuation coefficient show that here, cp decreases to values much lower than the values found above the DCM for similar chlorophyll concentrations. This might indicate that at these depths remineralization becomes a dominant process. Lower values of cp for similar values of chlorophyll concentrations found in the upper layer is consistent with cells that are degraded and thus reduced in size as they sink from the DCM to the deep ocean.

USE OF MODIS OCEAN COLOR IMAGERY FOR IMPROVED DETECTION AND MONITORING OF KARENIA BREVIS BLOOMS IN THE GULF OF MEXICO

Amin, Ruhul¹; Zhou, Jing¹; Gilerson, Alex ¹; Gross, Barry¹; Moshary, Fred¹; Ahmed, Sam<sup>1

1</sup>140 St @ Convent Ave, New York, NY, 10031, United States

Karenia brevis (K. brevis) blooms are of great interest and have been commonly reported throughout the Gulf of Mexico. However, detection still remains a challenge from space with standard bio-optical algorithms due to the uncertainty of atmospheric correction, and interference from high concentrations of organic and inorganic materials in optically complex coastal waters. We propose a simple normalized difference technique, which for convenience we call the K. brevis bloom index KBBI = (Rrs(678)-Rrs(667))/ (Rrs(678)+Rrs(667)), capable of detecting potential areas of K. brevis blooms from MODIS ocean color measurements. This index takes advantage of low backscattering efficiency of K. brevis. Remote sensing reflectance has a local minimum around 667nm (MODIS band 13) which is less than the signal at 678nm (MODIS band 14) when chlorophyll fluorescence is a significant fraction of water leaving radiance in the red bands; this increases the KBBI numerator. At the same time, lower reflectance values reduce the index denominator. As a result, the KBBI as a function of chlorophyll concentration for K. brevis differs from the similar function for the non- K. brevis blooms allowing K. brevis bloom detection to be more accurate and reliable. To assess the index, simulations including chlorophyll fluorescence based on the non-K. brevis bloom and K. brevis bloom were performed to determine the threshold of the detection conditions for possible K. brevis bloom using this technique. The approach was successfully applied to well documented blooms of K. brevis in the Gulf of Mexico and compared to other detection techniques, including FLH. Initial comparison indicates that this technique is generally capable of defining the area of K. brevis blooms more precisely and with fewer false alarms in the highly scattering and/or CDOM rich waters.

A NEW ALGORITHM FOR CALCULATING PRODUCTIVITY FROM OCEAN COLOR DERIVED CHLOROPHYLL-A

Marra, John¹; Hyde, Kimberly²; O'Reilly, Jay<sup>2

1</sup>Brooklyn College/CUNY 2900 Bedford Ave, Brooklyn, NY, 11210, United States; ²NOAA, Narragansett, Rhode Island, 02883, Afghanistan

We investigate the use of a new model, Ocean Productivity from Absorption and Light (OPAL) in calculating primary productivity from ocean color. (2003). The OPAL model generates profiles of chlorophyll estimated from the SeaWiFS chlorophyll using the algorithm from the literature and uses the absorption properties in the water column to vertically resolve estimates of light attenuation in approximately 100 strata within the euphotic zone. Absorption by pure water is assumed to be a constant value over PAR wavelengths; chlorophyll-specific phytoplankton absorption is parameterized empirically; absorption by photosynthetic pigments is distinguished from total absorption; and absorption by colored dissolved organic matter (CDOM) is calculated based on the idea that upwelled water will have a high CDOM, which then becomes photo-oxidized with time near the surface. The chlorophyll-specific phytoplankton absorption is used to calculate productivity, while absorption by pigments, water, and CDOM are used to vertically resolve light attenuation. SST, which is used as a proxy for seasonal changes in the phytoplankton community, is related to the chlorophyll-specific absorption coefficient. The quantum efficiency is obtained from a hyperbolic tangent and a constant φmax. The model is tested using in situ productivity data from our database. A global map of productivity will be shown.

SEASONAL VARIABILITY IN THE LIGHT ABSORPTION COEFFICIENT OF PHYTOPLANKTON, NON-ALGAL PARTICLES, AND COLORED DISSOLVED ORGANIC MATTER FOR WESTERN ARCTIC WATERS: IMPLICATIONS FOR DERIVING THE INDIVIDUAL COMPONENTS OF ABSORPTION USING OCEAN COLOR

Matsuoka, Atsushi¹; Hill, Victoria²; Babin, Marcel<sup>1

1</sup>Laboratoire d'Oceanographie de Villefranche (LOV) 06238 Villefranche-sur-mer Cedex, France, Villefranche-sur-mer, --, 06238, France; ²Earth and atmospheric sciences, the department of ocean, Norfolk, VA, 23529, United States

The light absorption properties of particulate and dissolved materials determine the behavior of visible light in oceanic waters and therefore, the accuracy of ocean color based algorithms. While the general absorption properties of these materials have been reported for western Arctic waters, their seasonal variability remains unknown. This is of particular importance as recent declines in sea ice cover have made possible longer seasonal ocean color observations of the western Arctic and the performance of global and regional algorithms needs to be assessed to allow analysis of biogeochemical processes. We investigated the light absorption coefficients of phytoplankton [a_φ(λ)], non-algal particles [a_NAP(λ)], and colored dissolved organic matter [a_CDOM(λ)] through all ice-free periods (from May to October) in the western Arctic. a_φ(440) covaried strongly with chlorophyll a (chl a), although the chl a specific a_φ(440) [a_φ(440)*] declined significantly from spring to autumn. The lower a_φ(440)* can be explained by the seasonal succession from smaller to larger sized phytoplankton species. Despite the seasonal variability, the a_φ(440) was also highly correlated with a_φ(λ) at other wavelengths (i.e., 410, 490, 510, 555, 620, and 670 nm) which approximately correspond to the band of SeaWiFS, MODIS and MERIS ocean color sensors. The spectral slope of a_NAP(λ) from the blue to the red was relatively constant, while that of a_CDOM(λ) from the blue to the green showed inverse correlation with a_CDOM(440). Variability in these two components was significantly different among seasons. These results suggest that when chl a and the related absorption coefficients of constituents in waters are derived from ocean color, the seasonal variability in a_φ(λ), a_NAP(λ), and a_CDOM(λ) should be considered.

DEVELOPMENT OF SIMULTANEOUS MULTI-WAVELENGTH EXCITATION FLUOROMETER

Oishi, Tomohiko¹; Tanaka, Akihiko¹; Yano, Shintaro¹; Ebata, Hiroki¹; Takahashi, Yo-hei¹; Kondo, Naotake¹; Tan, Hiroyuki²; Doerffer, Roland<sup>2

1</sup>Tokai University Orido 3-20-1, Shimizu-Ku, Shizuoka City, --, 424-8610, Japan; ²GKSS Research Centre, Geestchacht/Max-Plank Strasse, Hamburg, 21502, Germany

A simple and cost effective Simultaneous Multi-wavelength Excitation Fluorometer is presented. Using a newly developed excitation method, we show that the wavelength dependence of fluorescence at a given excitation wavelength can be easily retrieved. Our proposed method is that the fluorescence from a sample detected by a single sensor is excited simultaneously with different wavelength. Another advantage of the method is that the measurement time is independent with the number of excitation wavelength we use.

Further, by extending this method, we demonstrate that we can easily realize an in-situ type fluorometer, which obtain the excitation-emission fluorescence contour map of phytoplankton. The results show that we could determine theclass of phytoplankton by utilizing the difference of the excitation-emission fluorescence contour map, although it is first trial. It is promising method for used in field validations concerning ocean colour remote sensing

INFLUENCE OF MEASUREMENT AND ENVIRONMENTAL CONDITIONS ON BOTTOM REFLECTANCE MEASUREMENTS

Pinnel, Nicole¹; Gege, Peter <sup>2

1</sup>Murdoch University South St , Murdoch , --, WA, 6150, Australia; ²German Aerospace Center (DLR), Wessling, Oberpfaffenhofen, 82234, Germany

Bottom albedo measurements are often used as input of optical inversion models for shallow water habitat mapping as e.g. macrophytes species, seagrass and coral reef habitats. Spectral discrimination of various species underwater have first to be understood before they can be mapped using physical based remote sensing techniques. To make quantitative conclusions about species discrimination, spectral libraries are essential to extract these fingerprints of various substrate types. However such spectral libraries generally contain errors as they often are highly influenced by environmental conditions, such as changing illumination, sunangle, wave action, watercolumn and varying substrate densities, often leading to high exclusion of valuable spectral readings and/or time intensive statistical corrections. This results in major difficulties in making them transferable to other shallow water systems or comparison with other spectral libraries. Physical understanding of various factors which influence bottom albedo is therefore essential. Radiance and irradiance reflectance spectra of homogeneous freshwater macrophytes measured with a submersible spectroradiometer in 2003 and 2004 at two different lakes were used to investigate these influencing factors. The aim is to provide better understanding of underwater measurements, improve spectral separability between classes and achieve a better comparison between spectral libraries making exchange of such databases more reliable.

RADIANCE REFLECTED FROM A WIND BLOWN SURFACE CALCULATED FROM MEASUREMENTS

Høkedal, Jo<sup>1

1</sup>Narvik University College PO Box 385, Narvik, --, 8505, Norway

A set of measured radiance has been used to compute the reflected radiance on a wind blown sea-surface. Direct solar radiance and diffuse sky radiance have been measured on clear sky occations at different wavelengths, solar elevations and directions. Using a numerically modelled surface, with slopes as described by Cox and Munk, the surface reflected radiance has been calculated for numerous conditions. The calculated reflected radiances are then studied as function of direction, incident radiance and wind conditions.

LONG TERM STATISTICS OF REMOTELY SENSED PARAMETERS IN THE BALTIC SEA WITH MERIS-DATA

Krawczyk, Harald¹; Neumann, Andreas¹; Riha, Stefan<sup>1

1</sup>German Aerospace Center Rutherfordstreet 2, Berlin, --, D-12489, Germany

The Baltic Sea is an important ecological factor for all the riparian states. Therefore there is a high interest to continuously obtain detailed information about its ecological state. Due to a pan-European interest in the survey of the marine and coastal environment - ESA funded the GMES Service Element project MARCOAST started in 2005. Within the frame of this project a regular (daily) service of the determination of water properties basing on the interpretation of MERIS data was established. It allows a routine estimation of the quality of all relevant European water basins/areas. DLR developed a number of algorithms allowing the interpretation of water constituent parameters with special focus to the specific inherent bio-optical properties of the Baltic Sea. They allow the provision of quantitative maps of Chlorophyll, Suspended Matter, Gelbstoff and Water Transparency. The results are regularly provided to the State Ministry for the Environment, Nature Conservation and Geology of the state Mecklenburg-Vorpommern (LUNG). Since the start of the project in 2005 a large number of data could be collected and can now be subjected to a broad statistical analysis. The current presentation will describe the used interpretation scheme and algorithms and investigate the long-term statistical behavior of the mentioned parameters for different years. This gives interesting inputs for climatologic data bases and can be a valuable contribution for the estimation of the time development of the Baltic Sea water quality. Additionally a number of comparisons of remotely sensed parameters with in-situ measurements will be shown and discussed.

VALIDATION OF VARIOUS REMOTE SENSING ALGORITHMS FOR ESTIMATION OF ABSORPTION BY COLORED DISSOLVED ORGANIC MATTER IN THE BALTIC SEA FROM SEAWIFS AND MODIS IMAGERY

Kowalczuk, Piotr¹; Darecki, Miroslaw¹; Zablocka, Monika²; Gorecka, Izabela<sup>1

1</sup>Institute of Oceanology PAS Powstancow Warszawy 55, Sopot, --, 81-712, Poland; ²Institute of Oceanography, University of Gdansk /al. Marszalka Pilsudskiego 46, Gdynia, POMORSKIE, PL 81 - 378, Poland

Colored dissolved organic matter (CDOM) is one of the major determinants of the optical properties of natural waters and it directly affects both the availability and spectral quality of light in the water column. The CDOM is a part of the Dissolved Organic Matter pool and through its optical signatures its possible to estimate the concentration of Dissolved Organic Carbon in coastal areas. Thus ocean color remote sensing may be applied in carbon cycle studies in the coastal ocean and semi-enclosed seas. An extensive bio-optical data set from field measurements was used to evaluate the performance of two semi-analytical: GSM01 (Maritorena et al., 2002) and Carder et al., (1999) and one empirical (Kowalczuk et al., 2005) algorithms for estimation of CDOM absorption have been validated in the Baltic Sea. The data set includes coincident measurements of radiometric quantities, and absorption coefficient of CDOM, which were taken on 33 cruises between 2000 and 2006. At first stage of the analysis the accuracy of the empirical algorithm by Kowalczuk et al., (2005) has been assessed using in situ measurements of the remote sensing reflectance. The CDOM absorption coefficient, aCDOM(400), has been estimated with an error that exceeded 155% (RMS). Validation results improved greatly, when matching points located in Gulf of Gdansk close to Vistula River outlet have been eliminated from the data set: errors in a_CDOM(400) estimation were: Bias = 5%, RMS = 54%, R² = 0.43. In the second stage of the analysis the empirical algorithm has been tested on the satellite data from SeaWiFS and MODIS imagery. The satellite data were atmospherically corrected with the MUMM algorithm designed for turbid coastal and inland waters and implemented in the SeaDAS software. Results of the best case scenario of estimation of CDOM absorption coefficient, a_CDOM(400), based on the SeaWiFS data were: Bias = -1.7%, RMS = 23.6%, R² = 0.50. Application of MODIS data leads to less accurate estimation of the a_CDOM(400): Bias = -3.3%, RMS = 19.4%, R² = 0.38. Accuracy assessment of performance of standard semi-analytical algorithms available in the SeaWiFS and MODIS imagery processing software has revealed that both algorithms (GSM_01 and Carder) underestimate the CDOM absorption in the Baltic Sea with mean systematic and random errors that exceed 70%.

OCEAN COLOUR, BIO-OPTICS AND HARMFUL ALGAL BLOOMS: A GEOHAB PERSPECTIVE

Bernard, Stewart¹; Babin, Marcel²; Kudela, Raphael M³; Allen, Icarus<sup>4

1</sup>GEOHAB SSC and CSIR, 1 Jan Cilliers Street, Stellenbosch, --, 7599, South Africa; ²GEOHAB SSC & Laboratoire d'Océanographie de Villefranche, Villefranche-Sur-Mer, Provence-Alpes-Cote d'Azur, 06238, France; ³GEOHAB SSC & University of California Santa Cruz 1156 High Street, Santa Cruz, CA, 95064, United States; ⁴GEOHAB SSC and Plymouth Marine Laboratory, Prospect Place, Plymouth, Devon, PL1 3DH, United Kingdom

he GEOHAB programme seeks to address the development of improved remote observation systems for harmful algae: identifying gaps in knowledge, and stimulating development and improved application of relevant techniques. Ocean colour remote sensing has demonstrated considerable potential for the observation of harmful algal blooms (HABs). However, there are still fundamental problems with the application of rigorous ocean colour techniques in optically complex coastal waters. The high levels of uncertainty currently associated with coastal products compromise many HAB applications seeking to make use of remotely sensed data e.g. bloom detection and tracking, empirical ecological studies, and coupled ecological-hydrodynamic models. The challenges facing ocean colour based harmful algal applications are reviewed here, using studies from a variety of coastal ecosystems. Atmospheric correction schemes considered suitable for the open ocean often perform poorly in turbid, atmospherically complex coastal waters, where a lack of suitable validation data hampers improvement. In addition, the often high biomass associated with many HAB events, and Case-2 water problems, lead to the failure of standard ocean colour products. Better coastal data and new specific products are needed, and some new approaches are discussed - fluorescence line height, and analytical and red wavelength based algorithms. HAB detection places rigorous demands on our understanding of causal processes; radiative transfer and empirical studies examining the potential and problems for the detection of algal community change in different systems are discussed. In situ bio-optical instrumentation similarly has considerable potential in harmful algal focused observations systems, and HAB applications are often used as development and marketing motivators. However, there is a need for robust, inexpensive instrumentation that can be easily implemented by coastal groups globally, and potential approaches for achieving this are discussed.

BIOGEO-OPTICS: THEORETICAL AND APPLIED ASPECTS OF MINERAL AND ORGANIC MASS-SPECIFIC SCATTERING CROSS-SECTIONS

Stavn, Robert Hans¹; Richter, Scott<sup>2

1</sup>University of North Carolina/Greensboro PO Box 26174, Greensboro, NC, 27402-6174, United States; ²PO Box 26174, Greensboro, NC, 27402-6174, United States

There are more and more uses of mass-specific scattering cross sections of suspended particulates being discovered, such as the inversion of remote-sensing reflectance to determine concentrations of suspended mater. It is therefore important to explore the theoretical limits of this parameter. It is conveniently measured in the field and it has significant theoretical content. The choice of particle size distribution significantly affects the mass-specific scattering cross section and we will explore the theoretical consequences of choosing realistic and unrealistic particle size distributions in determining these limits.

Recently we described a new method of partitioning the particle scattering coefficient into two major components, mineral and organic. The method employs mass-specific scattering cross sections determined from a new Model II multiple linear regression model. We demonstrate the characteristics of this regression model that make it an optimum estimator of mass-specific scattering cross sections. The Model I estimate of the first independent variable (mineral mass-specific scattering cross section) is always an underestimate of the mass-specific scattering cross section. The second independent variable (organic mass-specific scattering cross section) can be either an overestimate or an underestimate of the mass-specific scattering cross section, which has not been observed before.

There are significant differences in the suspended mineral matter of the western and eastern portions of the northern Gulf of Mexico. Variations in the content of suspended particulate mineral matter in the northern Gulf of Mexico and its effect on the mass-specific mineral scattering cross sections and remote-sensing reflectance will be demonstrated.

CHARACTERIZING WATER MASS PROPERTIES IN RIVER DOMINATED COASTAL WATERS USING UNDERWAY HYPERSPECTRAL REMOTE SENSING REFLECTANCE

Lohrenz, Steven¹; Cai, Wei-Jun²; Chen, Xiaogang¹; Tuel, Merritt<sup>1

1</sup>University of Southern Mississippi 1020 Balch Boulevard, Stennis Space Center, MS, 39529, United States; ²University of Georgia, Athens, Georgia, 30602, United States

A focus of current research in aquatic optics is to improve our understanding of the diverse processes that influence optical properties and their relationship to key constituents including algal pigments, chromophoric dissolved organic matter and suspended particulate matter. Optically complex coastal waters represent a challenge for ocean color remote sensing because of the high degree of spatial heterogeneity and limitations in the performance of algorithms. Ship-based underway hyperspectral observations of remote sensing reflectance provide a means for improved spatial resolution and greater degrees of freedom for semi-analytical algorithms. Here we describe a series of complementary observations of surface hyperspectral radiance and irradiance and in situ measurements of apparent and inherent optical properties and key constituents in coastal waters of the northern Gulf of Mexico. The HyerSAS-UV system was used to provide above-water measurements of radiance and irradiance, as well as extended spectral range into the UV-B, thereby yielding broad spatial and temporal coverage and higher frequency sampling. Results illustrate the utility of remote sensing reflectance as means of tracking water mass properties in an optically complex coastal regime, the Mississippi River plume.

TOWARD THE DEVELOPMENT OF AN OIL SLICK DETECTION SYSTEM USING OPTICAL DATA

Bignami, Francesco¹; Pisano, Andrea ¹; Santoleri, Rosalia¹; Evans, Robert<sup>2

1</sup>Via Fosso del Cavaliere 100, Rome, --, 00133, Italy; ²RSMAS, UMIAMI , Miami, florida, FL 33149-1098, United States

The object of this work is to present the first results of the Italian Space Agency-funded project PRIMI for the development a modular system for the operational monitoring (observation via SAR and optical remote sensing, forecasting, report generation) of marine pollution caused by hydrocarbon spills in the Mediterranean Sea. We present a new methodology for the detection of oil spills at sea using MODIS data. The methodology was developed using the imagery relative to a set of known oil spill cases (Lebanon coastal oil spills of July-August 2006). This technique consists in oil/water contrast enhancement via the elimination of the oceanic, Rayleigh scattering and part of the aerosol signals in the TOA reflectances (MODIS rhot_nnn product) in selected visible and near infrared bands. The elimination of the above natural variability leaves a ‘flattened’ version of the input reflectance image in each band, in which oil slicks tend to stand out more distinctly than in the original rhot_nnn image. These flattened images in the selected bands are then fed to a segmentation/clustering algorithm, which identifies a variable number reflectance mode values in each scene, thus classifying the latter in a set of sub-regions, some of which contain the oil slicks. The simplification of the original image with a continuous variability into a clustered image with a restricted number of modes encodable into colors enables a trained operator to more readily identify oil slicks. Also, the possibility of completely automatizing the detection process is discussed.

VARIABILITY IN GLOBAL OCEAN PHYTOPLANKTON DISTRIBUTION OVER 1979-2006

MASOTTI, Italo¹; ALVAIN, Severine²; MOULIN, Cyril¹; ANTOINE, David<sup>3

1</sup>LSCE/IPSL (CEA-CNRS-UVSQ) CEA Saclay - bat. 712, Gif-sur-Yvette, --, 91191, France; ²LOG (CNRS-ULCO-USTL), Wimereux, Nord, 62930, France; ³LOV (CNRS-UPMC), Villefranche-sur-Mer, Sud, 06238, France

Recently, reanalysis of long-term ocean color data (CZCS and SeaWiFS; Antoine et al., 2005) has shown that world ocean average phytoplankton chlorophyll levels show an increase of 20% over the last two decades. It is however unknown whether this increase is associated with a change in the distribution of phytoplankton groups or if it simply corresponds to an increase of the productivity. Within the framework of the GLOBPHY project, the distribution of the phytoplankton groups was monitored by applying the PHYSAT method (Alvain et al., 2005) to the historical ocean color data series from CZCS, OCTS and SeaWiFS sensors. The PHYSAT algorithm allows identification of several phytoplankton, like nanoeucaryotes, prochlorococcus, synechococcus and diatoms. Because both sensors (OCTS-SeaWiFS) are very similar, OCTS data were processed with the standard PHYSAT algorithm to cover the 1996-1997 period during which a large El Niño event occurred, just before the SeaWiFS era. Our analysis of this dataset (1996-2006) evidences a strong variability in the distribution of phytoplankton groups at both regional and global scales. In the equatorial region (0°-5°S), a three-fold increase of nanoeucaryotes frequency was detected in opposition to a two-fold decrease of synechococcus during the early stages of El Niño conditions (May-June 1997, OCTS). The impact of this El Niño is however not confined to the Equatorial Pacific and has affected the global ocean. The processing of CZCS data with PHYSAT has required several adaptations of this algorithm due to the lower performances and the reduced number of spectral bands of the sensor. Despites higher uncertainties, the phytoplankton groups distribution obtained with CZCS is globally consistent with that of SeaWiFS. A comparison of variability in global phytoplankton distribution between 1979-1982 (CZCS) and 1999-2002 (SeaWiFS) suggests an increase in nanoeucaryotes at high latitudes (>40°) and in the equatorial region (10°S-10°N ) for prochlorococcus and synechococcus during 1999-2002. Our results show variability in global ocean phytoplankton distribution over a 20-year timescale. Strong variability observed over the inter-annual and inter-decadal scales must be explained in order to understand which environmental variables control this shifting phytoplankton distribution.

BIO-OPTICAL CONTROL ON REFLECTANCE IN THE NORTH EASTERN MEDITERRANEAN

Örek, Hasan¹; Beşiktepe, Şükrü Turan<sup>2

1</sup>METU-IMS Middle East Tech. Univ. Inst. of Marine Sciences. Erdemli, Mersin, --, tr33731, Turkey; ²NATO Undersea Research Centre, Viale San Bartolomeo, Genova, La Spezia, 19126, Italy

Comprehensive set of data collected during 2001-2005 reveal seasonal and inter annual variability in the bio-optical properties of the Northeastern Mediterranean. The data set includes upward and downward spectral irradiances, particle (Phytoplankton and Detritus), and CDOM absorption and phyto-pigment composition measured by HPLC. Irradiance measurements have done by Li-core UW1800 spectroradiometer both upward and downward. Irradiance reflectance was calculated from these measurements. Optical properties like diffusivity, reflectance, are controlled by particle or CDOM absorption or phytoplankton composition. Temporal and spatial variability of reflectance between offshore and coastal regions are observed. It was found that usually phytoplankton activity is controlling the reflectance properties at offshore; however concentration is not only controlling mechanism. Species composition is main reason reflectance variability. Reflectance peak values are changing between 400 to 500 nm in both offshore and coastal regions, but peak position in coastal regions are usually occurring between 450-500 nm. In offshore, peak shape and position are very variable according to phytoplankton composition. In summer period (May-August) system is usually dominated by Cyanobacteria and reflectance peaks are appearing around 410-420 nm. In winter, starting from late autumn, peak shape became broaden between 400-500 nm. Different than single peak shape reflectance, broaden and double peak shapes are observed in winter, where chlorophyll values are higher also. The main difference in this period is the species composition of phytoplankton. Whereas, in transition periods like in April both high CDOM and Chlorophyll and Phytoplankton absorption values observed with same reflectance peak shape in summer, that chlorophyll, CDOM etc. are relatively low. However, similar to summer period Cyanobacteria were dominating during April. As a conclusion; spatial and temporal variability of the optical properties of the N.E. Mediterranean is also controlled by species composition.

OCEAN COLOUR SENSORS CHARACTERISATION AND ERROR ESTIMATES OF RETRIEVED MERGED PARAMETERS FROM THE GLOBCOLOUR PROJECT

Fanton d'Andon, Odile Hembise¹; Antoine, David²; Mangin, Antoine³; Maritorena, Stéphane⁴; Durand, Dominique⁵; Pradhan, Yaswant⁶; Lavender, Samantha Jane⁷; Morel, André<sup>2

1</sup>ACRI 260 Route du Pin Montard, Sophia Antipolis, --, 06 904, France; ²Laboratoire d'Océanographie de Villefranche, Quai de La Darse, BP 8 , Villefranche sur Mer Cedex, PACA, 06238 , France; ³260 Route du Pin Montard, Sophia Antipolis, --, 06 904, France; ⁴University of California at Santa Barbara, 6841 Ellison Hall, Santa Barbara, CA 93106-3060, 93106-3060, United States; ⁵NIVA, Nordnesboder 5, PoBox 2026, Bergen, Bergen, N-5817 , Norway; ⁶University of Plymouth, Portland Square A403, Drake Circus, Plymouth, Devon, PL4 8AA, United Kingdom; ⁷ARGANS Limited, Tamar Science Park, 1 Davy Road, Derriford, Plymouth, Devon, PL6 8BX, United Kingdom

The ESA GlobColour project has produced a ten year time series of merged ocean colour products from available sensors (SeaWiFS, MODIS-Aqua, MERIS). The complete data set is available to the scientific community ( www.globcolour.info) and to the key users of the project (IOCCP, IOCCG and UKMO) in particular. Before the production of such a data set, a significant effort has been put on merging strategies and the characterisation of the input data. This analysis was conducted through an exhaustive match-up analysis for each of the sensors which has allowed the estimation of the uncertainties associated with each sensor as well as cross-comparisons among sensors. Error statistics from the initial sensor characterisation are used as an input to both the weighted averaging and the GSM merging methods, and propagate through the merging process to provide error estimates on the output merged products. The error estimates resulting from both merging methods and affecting the final bio-geophysical products were estimated and are presented and commented.

BIO-OPTICAL STUDIES ALONG THE PATAGONIAN SHELF-BREAK ZONE

Garcia, Carlos Alberto Eiras¹; Garcia, Virginia M. T.¹; Romero, Silvia I.²; Ferreira, Amábile¹; Dogliotti, Ana I.¹; Signorini, Sergio³; McClain, Charles R.<sup>3

1</sup>Federal University of Rio Grande Av Itália km 8, Rio Grande, --, 96201-900, Brazil; ²Servicio de Hidrografía Naval (SHN), Buenos Ayres, Ciudad de Buenos Aires, C1270 AVB, Argentina; ³Goddard Space Flight Center, Greenbelt, Maryland, MD 20771, United States

Ocean color images from the Patagonia shelf break in the Southwestern Atlantic Ocean, usually show high phytoplankton biomass patches during spring and summer periods.. The PATagonia EXperiment (PATEX) was specially designed to investigate the environmental factors that control the occurrence of these blooms, to characterize the phytoplankton assemblage and primary production rates, to determine the main nutrient levels and ratios associated with the bloom waters, to determine their bio-optical characteristics and the CO₂ fluxes in the studied area. Five cruises were conducted in November 2004, October 2006, March 2007, October 2007 and January 2008 when more than 120 oceanographic stations were occupied for physical, biogeochemical and optical studies along the large bloom extent in the Patagonian shelf-break (approximately 55,000 Km² of chlorophyll concentration >2 mg m^-3 chlorophyll patch). In this article, we report the physical environmental setting for biological production and the seawater bio-optical properties (spectral reflectance, backscattering, absorption of particles, beam attenuation, phytoplankton and colored dissolved organic matter, and chlorophyll-a concentration) measured during these five cruises. We found a remarkable bloom of diatoms and flagellates (~ 1,200 Km extension) in spring, which precedes the summer coccolithophore bloom in the frontal region. Primary production rates during the spring blooms were comparable with maxima seasonal productivity at Eastern Boundary Currents. Surface chlorophyll concentration ranged from 0.2 to 20 mg/m^-3 during the cruises. Particle (phytoplankton and detritus) and CDOM absorption coefficients measured in these waters were highly variable and showed a seasonal dependence. Comparisons between in-situ and satellite measurements (MODIS and SeaWiFS) of remote sensing reflectance, surface chlorophyll and inherent optical properties are also made in this work.

DERIVATIVE ANALYSIS OF LIGHT ABSORBANCE IN THE OPTICAL PHYTOPLANKTON DISCRIMINATOR

Kirkpatrick, Gary¹; Lohrenz, Steven ²; Moline, Mark³; Schofield, Oscar<sup>4

1</sup>Mote Marine Laboratory 1600 Ken Thompson Parkway, Sarasota, FL, 34236, United States; ²University of Southern Mississippi, Stennis Space Center, MS, 39529, United States; ³California Polytechnic State University, San Luis Obispo, CA, 93407, United States; ⁴Rutgers University, New Brunswick, NJ, 08903, United States

The Optical Phytoplankton Discriminator (OPD), first developed in the late 1990s as a harmful algal bloom detector (BreveBuster), has demonstrated applicability for CDOM mapping, phytoplankton community structure analysis and is currently being assessed for factoring the components of absorption in whole water. It has been adapted for deployment on ships, buoyancy and propeller driven autonomous underwater vehicles, buoyancy driven vertical profilers, buoys, channel marker and piers. The data stream from this network of instruments is received, processed and distributed by the Sarasota Operations of the Coastal Ocean Observation Laboratories to appropriate end users and displayed on the Web. The OPD is a hyperspectral device operating in the wavelength range from 300 to 800 nm with a spectrometer dispersion of 0.32 nm/pixel and an optical resolution of approximately 2.1 nm. Hence, the acquired particle absorbance spectra have high information content. The key to extracting the available information about pigmented particles has been the use of fourth derivative analysis. The application of multiple derivatives strongly attenuates monotonic and near-monotonic functions such as scattering and detrital absorption. Therefore, the spectra resulting from fourth derivative analyses represent only the pigment ensemble of the observed phytoplankton. These pigment spectra have been applied to correlation analyses against target harmful algal species as a non quantitative estimate of presence/absence. They have also been factored using a least-squares multiple regression routine of algal class libraries to obtain quantitative estimates of phytoplankton community taxonomic structure. Most recently, an attempt is being made to estimate the other components of light loss including scattering and detrital absorption in the instrument. This effort is utilizing iterative multiple regression and multiple integration routines.

PERFORMANCE PREDICTION FOR UNDERWATER ELECTRO-OPTICAL MINE IDENTIFICATION SYSTEMS

Giddings, Thomas¹; Shirron, Joseph<sup>1

1</sup>Metron, Inc. 11911 Freedom Dr., Reston, VA, 20190-5602, United States

Several electro-optical identification (EOID) systems are currently being incorporated into mine countermeasures (MCM) operations. The inclusion of these systems in fleet operations is accompanied by the need for accurate, robust, and timely EOID system performance predictions for effective mission planning. EODES software provides high-fidelity, validated models for several underwater EOID systems, including tools to compute performance estimates, determine optimal operational settings, and generate simulated images. The performance analysis products provide several key performance parameters required by tactical decision aids to assist in the development, planning, and execution of MCM missions. In particular, the performance prediction products may be used to guide asset allocation, track planning, and lane spacing decisions, and also to estimate MCM timelines, risk to MCM platforms, and the residual threat to maritime forces.

The performance of EOID systems is highly dependent on the optical properties of the operational environment. An accurate characterization of the optical properties in the areas of operations is therefore an important input to the EODES models. New developments in environmental sensing and computer modeling are making high-quality meteorological and oceanographic (METOC) data available to systems analysis tools such as EODES. Here we describe the physical and numerical models used to predict the environmental impact on EOID system performance, and show results from recent fleet exercises to illustrate how model outputs are used to aid in the development of operational tactics. In addition to operational applications, these performance estimates are also used in the design and evaluation of prospective systems and to inform investment and acquisition decisions to help ensure that an effective array of MCM assets is available to forces in the field.

DYNAMICS OF COLLOIDAL PARTICLES ASSOCIATED WITH VIRAL INFECTION OF MARINE BACTERIA

Uitz, Julia¹; Baudoux, Anne-Claire²; Wright, Vanessa M.¹; Malfatti, Francesca ²; Dubranna, Jean¹; Stramski, Dariusz¹; Azam, Farooq <sup>2

1</sup>Scripps Institution of Oceanography - Marine Physical Lab 9500 Gilman Drive, La Jolla, CA, 92093-0238, United States; ²Scripps Institution of Oceanography - Marine Microbiology Lab 9500 Gilman Drive, La Jolla, CA, 92093-0202, United States

Although viruses are among the most abundant colloidal particles in the ocean, their direct impact on ocean optics is thought to be of minor importance. Nonetheless, the particles produced by the lysis of bacteria or phytoplankton following viral infection may significantly affect marine optical properties, especially light backscattering. Furthermore, viral-induced lysis products could serve as “seeds” for particle aggregation, which in turn may supply hotspots for microbial processes and promote sinking of particulate matter into the deep ocean. An experiment was conducted to examine the formation of colloidal particles resulting from the viral infection of the antagonist marine bacteria SWAT-3, over a 3-day period. Our approach relies primarily on the use of a flow field-flow fractionation (Fl FFF) system integrated with a multi-angle light scattering meter. Fl FFF allows a size-based fractionation of macromolecules and colloids, while the scattering sensor measures the volume scattering function of the fractionated samples. The angle-dependent light scattering signal is then inverted to determine the size distribution of colloids. Our measurements were supplemented with other analyses, including the enumeration of viruses and bacteria by epifluorescence microscopy and particle counting with an electrical resistive particle sizer (Coulter). An increase in the abundance of viruses was detected 6 hours after infection, and most of bacterial cells underwent lysis within 12 hours. The increase in viral abundance was accompanied by the formation of significant amounts of colloids, primarily within the size range 100-300 nm (equivalent spherical diameter). In contrast, colloidal particles remained undetectable in the non-infected bacteria (control) samples. Our results indicate that viral infection stimulates the production of small colloidal particles which could aggregate to form larger-sized colloids and microparticles on time scales from several hours to a few days.

BIO-OPTICAL OBSERVATIONS OF THE NORTH ATLANTIC SPRING BLOOM

Westberry, Toby K.¹; Dall'Olmo, Giorgio¹; Behrenfeld, Michael J.¹; Boss, Emmanuel<sup>2

1</sup>Oregon State University 2082 Cordley Hall, Corvallis, OR, 97331-2902, United States; ²School of Marine Sciences, University of Maine, Orono, ME, 04469, United States

The evolution of the North Atlantic Spring Bloom was observed using continuous, underway measurements of particle absorption and scattering indices in a ~10000 km² area centered on 61N, 26W. Spectral particulate beam attenuation (c_p), absorption (a_p), and backscattering (b_bp) were measured simultaneously using a novel flow-through system with an actuated valve and timer to intermittently direct seawater flow through 0.2 um filters. Initially, the phytoplankton community was dominated by large chain-forming diatoms, which were then succeeded by dinoflagellates and ultimately by picoeukaryotes, as revealed by flow cytometry, microscopy, and HPLC pigment analysis. Despite the wide range in taxonomic variability, consistent relationships between c_p and b_bp were observed. Further, the slope of this relationship was similar to that obtained in very different oceanic environments (from oligotrophic to mesotrophic). This covariability of the two scattering indices suggests that they are, in large part, sensitive to the same pool of particles or that the particle size distribution is relatively conserved across large gradients in bulk chlorophyll (and presumably chlorophyll degradation products, as well). Coulter counter-based particle size distributions ranged from perfectly Junge-like to having pronounced peaks over the size range investigated (2-60um). In contrast to previous studies in the region, the bio-optical imprint of coccolithophorids was not observed in any of the quantities measured. Empirical relationships between c_p, a_p, and b_bp with coincident biogeochemical measurements such as chlorophyll, particulate organic carbon, and biovolume-estimated phytoplankton specific carbon will also be discussed.

PHYTOPLANKTON BIO-OPTICAL MODELS USING POPULATIONS OF TWO-LAYERED SPHERES

Bernard, Stewart¹; Probyn, Trevor ²; Shillington, Frank<sup>3

1</sup>Council for Scientific and Industrial Research 11 Jan Cilliers Street, Stellenbosch, --, 7599, South Africa; ²Marine and Coastal Management, Bag X1, Roggebaai, Cape Town, Western Cape, 8001, South Africa; ³University of Cape Town, Private Bag, Rondebosch, Cape Town, Western Cape, 7701, South Africa

Inherent optical property and reflectance inversion models are presented, using a two-layered spherical geometry and equivalent size distribution scheme to simulate the optical properties of phytoplankton populations. The two-layered geometry is chosen as the simplest heterogeneous structure potentially capable of simulating algal angular scattering properties. Simple, single cell models are used to demonstrate the optical effects of varying cellular geometry, chloroplast volume and complex refractive index. The approach is expanded to polydispersed populations using equivalent size distribution models to demonstrate variability in simulated inherent optical properties for phytoplankton assemblages of changing dominant cell size and functional type. This algal population model is then used as a component of a forward reflectance model to compare modeled and measured reflectance data from high biomass blooms in the Benguela system. The approach is expanded to construct reflectance inversion algorithms for use with data from hyper-spectral in water reflectance, and multi-spectral satellite derived ocean colour. Preliminary validation, with an independent bio-optical data set from the southern Benguela, shows the algorithm capable of deriving Chl a concentrations through several orders of magnitude and an algal size descriptor under high biomass conditions. Algorithm performance is used to to briefly discuss returned phytoplankton backscattering characteristics. Finally, the algorithm is used with data from the MERIS sensor during several high biomass algal bloom events in the Benguela system to demonstrate potential utility for monitoring algal dynamics and detecting harmful algal blooms.

INHERENT OPTICAL PROPERTY MEASUREMENTS AND MODELING IN THE GREAT BARRIER REEF WORLD HERITAGE AREA

Slivkoff, Matthew¹; Mckinna, Lachlan²; Furnas, Miles<sup>3

1</sup>Curtin University / Australian Institute of Marine Science Kent St, Bentley, Perth, Western Australia, --, 6152, Australia; ²James Cook University, Townsville, Queensland, 4810, Australia; ³Australian Institute of Marine Science, Cape Ferguson, Queensland, 4810, Australia

There has been considerable interest in recent times to utilise data from polar orbiting SeaWiFS and MODIS sensors to assess and manage anthropogenic land runoff into the Great Barrier Reef system. The often turbid and complex nature of terrestrially-sourced materials demands ocean colour remote sensing algorithm approaches where the remotely sensed signal is decomposed into the water constituent Inherent Optical Properties (IOPS). Due to the latitudinal extent of the Great Barrier Reef and the geographical variability of the coastline that interacts with the reef, inherent optical property sampling was performed in an attempt to understand the regional and temporal variability of optically significant water constituents and how these optical properties relate to historically-measured water quality parameters in the region including Chlorophyll-a concentration, Total Suspended Solids and Dissolved Organic Carbon.

Phytoplankton and non-algal particulate absorption coefficients were determined from a modified Quantitative Filter Technique (QFT), along with spectrophotometric Coloured Dissolved Organic Matter (CDOM) absorption measurements. An ac-9 was used to verify the pathlength amplification factor of the modified QFT technique and to determine the total scattering coefficients for clear reef waters and turbid flood-plume waters. Backscattering measurements were also made using a Hydroscat-6.

Based on these measurements, a set of spectral IOP models were derived with the intention of using a radiative transfer model optimization technique to invert hyperspectral remote sensing reflectance measurements to determine three water quality parameters simultaneously (Chlorophyll-a, Total Suspended Solids, Dissolved Organic Carbon).

CDOM- ABSORPTION FROM TROPICAL BLACK WATER RIVERS TO OPEN OCEAN -CONTRIBUTIONS OF COLLOIDAL SIZE FRACTIONS

Siegel, Herbert¹; Gerth, Monika¹; Stottmeister, Iris¹; Alling, Vanja<sup>2

1</sup>Leibniz Institute for Baltic Sea Research Warnemünde Seestrasse 15, Rostock-Warnemünde, --, D-18119, Germany; ²University of Stockholm, Stockholm, Stockholm, Frescativägen 54 a, Sweden

Absorption of coloured dissolved organic substances (CDOM) was measured in different regions of the world ocean from tropical black water rivers, over enclosed seas to the open ocean. The highest absorption coefficients ever measured was recognised in tropical peat draining rivers of central Sumatra Island of Indonesia. Enclosed seas covered the Black-, North-, and the Baltic Seas. Lowest absorptions were determined in the open parts of the Indian and Atlantic Oceans including the Caribbean Sea. In the Baltic Sea horizontal gradients with a north-south decrease are stronger pronounced than seasonal variations. By partial thawing of the permafrost soil in northern Europe high CDOM content is transported into the Bothnian Bay the northern most part of the Baltic Sea. Therefore, the highest absorptions in the Baltic occurred in this area. Because of the strong ice coverage during the measuring campaign the rivers could not be sampled. The different ice layers in the ice cores contained also CDOM. Samples of that region were used to split the colloids into different size fractions by ultra filtration. The fraction < 0.01µm (<1kDa) delivered the highest contribution in the absorption coefficients. This systematisation presents not only the highest variation range of CDOM absorption coefficients ever published but also the spectral behaviour of a wide range of water masses.

SEASONAL VARIABILITY OF REMOTE SENSING FLUORESCENCE OVER THE SOUTHEAST BRAZILIAN CONTINENTAL SHELF

Ciotti, Aurea Maria¹; Barbosa, Fabiana Pestana<sup>1

1</sup>UNESP- CLP Praça Infante Dom Henrique S/N, Parque Bitaru, São Vicente, --, 01223-000, Brazil

Remote sensing natural fluorescence is a potential tool to estimate phytoplankton biomass over optical complex waters. Here we present a winter/summer analysis MODIS FLH (Fluorescence Line Height) variability over the continental shelf area between Cabo de São Tomé (RJ) and Cananéia (SP), were several sources of non-algal material exist. Biological production is moderate and nutrient input include continental outflow in the south and both costal and eddy-induced upwelling in the north. Previous studies show that CDOM is the major component for in situ light absorption. Global, weekly, level 3 MODIS-aqua and SeaWIFS images, with 4 km and 9 km spatial resolution respectively, were acquired from March 2005 to July 2007. Using SEADAS, maps of FLH, Chlorophyll-a, Sea Surface Temperature (SST), Normalized water-leaving radiance at 551 nm (nLw551) and Photosynthetically Active Radiation (PAR) were generated, and the interest area was divided into four main sub areas based on hydrographic features reported in the literature. For each sub area, the FLH was statistically related to all other estimated products, to identify the respective degrees of optical complexity. Results confirm an expected non-linear relationship between FLH and Chlorophyll-a in all sub areas and seasons, with smaller ratio values over the continental shelf during winter. However, FLH over the shelf decreased with the decrease of both SST and PAR, suggesting additional factors regulating FLH.

RESOLVING SURF ZONE PARTICLE DYNAMICS WITH HIGH SAMPLING RATE VOLUME SCATTERING FUNCTION MEASUREMENTS

Twardowski, Michael¹; Freeman, Scott¹; Vagle, Svein ²; Zhang, Xiadong³; Zaneveld, Ronald<sup>4

1</sup>WET Labs 165 Dean Knauss Dr, Narragansett, RI, 02882, United States; ²Institue of Ocean Sciences, Sidney, British Columbia, V8L 4B2, Canada; ³University of North Dakota, Grand Forks, North Dakota, 58202-9011, United States; ⁴WET Labs, Philomath, Oregon, 97370, United States

The surf zone is a dynamic and unique environment optically. Breaking waves generate submerged bubble particle populations at the air-sea interface which evolve rapidly over time and space. Wave action suspends sediment while surf zone currents continually redistribute water column particle fields. The physics driving these processes is not well understood. Optical property measurements were made off Scripps Pier, La Jolla, CA in January 2008 to better elucidate surf zone particle dynamics and the resulting optical impacts. Volume scattering function (VSF) measurements were resolved at 20 Hz at angles spanning 10 to 170 degrees in 10 degree increments with a prototype MASCOT device, and at 1 Hz with several multi-channel ECO sensors at angles in the backward direction between 100 and 150 degrees. The near-forward portion of the VSF from 0.1 to 20 degrees in 32 logarithmically spaced intervals was also measured at 1 Hz with a LISST device. Acoustic measurements of bubble size distributions were made concurrently with a bubble resonator affixed to the same instrument package. All measurements were made just below the air-sea interface by suspending the package over the side of the pier while the ebbing tide moved the surf zone past the package. Unique modification of the phase function was observed in passing suspended sediment plumes, in wave-injected bubble plumes, and combinations of these particle populations relative to the background. Specifically, sediment plumes exhibited higher relative backscattering levels than the background, while a clear phase function enhancement in the 60 to 80 degree range was observed in association with bubble plumes. Both features are consistent with theoretical predictions. Acoustic measurements corroborated the presence of bubbles. Phase function specificity for particle subpopulations should enable inversion of the VSF measured in the bulk sample to derive information such as size distribution and concentration of the primary subfractions as long as theoretical and/or empirical representations of the subfraction phase functions are accurate.

SEASONAL VARIATIONS IN THE OPTICAL AND PHOTOSYNTHETIC CHARACTERISTICS OF A COASTAL INLET

Bouman, Heather¹; Platt, Trevor²; Sathyendranath, Shubha<sup>3

1</sup>Oxford University Dept of Earth Sciences, Oxford University, Parks Rd, Oxford, --, OX1 3PR, United Kingdom; ²Bedford Institute of Oceanography, Dartmouth, Nova Scotia, B2Y 4A2, Canada; ³Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth, PL1 3DH, United Kingdom

Coastal ecosystems are subject to high levels of anthropogenic activity and therefore play an important role in issues of resource management. Continual monitoring of these waters is necessary to assess how human activity impacts the structure and function of these ecosystems and to estimate year-to-year fluctuations in their productivity. In situ optical sensors provide scientists with the potential of continual monitoring of changes in the ecological status of coastal waters over a range of spatial scales. By virtue of their close proximity to land, coastal waters are heavily influenced by optical components that are terrestrial in origin, which make the task of estimating the spectral quality and quality of irradiance available for photosynthesis difficult.

In this study, optical and photosynthetic characteristics of a coastal embayment (Bedford Basin, Nova Scotia) were measured with a nominal sampling frequency of once per week. Variability in the spectral shapes and magnitudes of absorption by CDOM, detritus and phytoplankton are assessed and their relationships with the physico-chemical and biological properties of the water column are examined. The influence of CDOM and phytoplankton absorption on the diffuse attenuation coefficients of spectral downwelling irradiance is discussed. In addition, changes in the photosynthetic properties of the phytoplankton community as they relate to variation in the optical and physical characteristics of the basin are explored. The implications of these findings for modelling primary production in coastal environments will also be addressed.

AERONET-OC: STRENGTHS AND WEAKNESSES OF A NETWORK FOR THE VALIDATION OF SATELLITE COASTAL RADIOMETRIC PRODUCTS

Zibordi, Giuseppe¹; Holben, Brent²; Slutsker, Ilya²; Giles, David²; D'Alimonte, Davide³; Melin, Frederic¹; Berthon, Jean-Francois¹; Vandemark, Doug⁴; Feng, Hui⁴; Schuster, Gregory⁵; Fabbri, Bryan ⁵; Kaitala, Seppo ⁶; Seppala, Jukka<sup>6

1</sup>Joint Research Centre Via E. Fermi 1, Ispra, --, 21027, Italy; ²NASA Goddard Space Flight Center, Greenbelt, MD, 20771, United States; ³Centro de Inteligencia Artificial / Universitade Nova de Lisboa, Caparica, Lisboa, 2819-516, Portugal; ⁴University of New Hampshire / OPAL, Durham, NH, 03824, United States; ⁵NASA Langley Research Center , Hampton, VA, 23681, United States; ⁶Finnish Institute of Marine Research , Helsinki , Helsinki, 00561, Sweden

The Ocean Color component of the Aerosol Robotic Network (AERONET-OC) has been implemented to support long-term satellite ocean color investigations through cross-site consistent and accurate measurements form above-water autonomous radiometer systems deployed on offshore fixed platforms. The ultimate purpose of AERONET-OC is the production of standardized measurements performed at different sites with identical measuring systems and protocols, calibrated using a single reference source and method, and processed with the same code.

The AERONET-OC primary data product is the normalized water leaving radiance determined at center-wavelengths of interest for satellite ocean color applications with uncertainties lower than 5% in the blue-green spectral regions and higher than 8% in the red.

Measurements from 6 sites counting the northern Adriatic Sea, the Baltic Proper, the Gulf of Finland, the Persian Gulf, and, the northern and southern margins of the Middle Atlantic Bay, have shown the capability of producing quality assured data over a wide range of bio-optical conditions including Case-2 yellow substance- and sediment-dominated waters.

This work briefly introduces network elements like: deployment sites, measurement method, instrument calibration, processing scheme, quality-assurance, uncertainties, data archive and products accessibility. Emphases is given to those elements which underline the network strengths (i.e., mostly standardization of any network element) and its weaknesses (i.e., the use of consolidated, but old-fashioned technology). The work also addresses the application of AERONET-OC data to the validation of primary satellite radiometric products over a variety of complex coastal waters and finally provides elements for the identification of new deployment sites most suitable to support satellite ocean color missions.

LOOKING AT “DENSE WATER” AND "FLUID SAND”. A CASE STUDY IN THE WADDEN SEA.

Hommersom, Annelies¹; Peters, Steef¹; Wernand, Marcel R.<sup>2

1</sup>Institute for Environmental Studies (IVM), Free University Amsterdam De Boelelaan 1085, Amsterdam, --, 1081 HV, Netherlands; ²Royal Netherlands Institute for Sea Research (NIOZ), Den Burg (Texel), P.O. Box 59, 1790 AB, Netherlands

The Wadden Sea is a shallow sea with mudflats and high concentrations of sand, chlorophyll and CDOM. In a period of two years 150 samples were taken to study the optical behaviour of the Wadden Sea. Total absorption and beam attenuation were measured with an AC9, CDOM absorption was measured in a cuvette, reflectance was measured with a TriOS system and concentrations of suspended particulate material, organic matter, and Chlorophyll-a were determined. Additional measurements included secchi depths, salinity, wind speed and - at some stations - filterpad measurements of chlorophyll-a specific pigment absorption and specific particle absorption.

These measurements are used to study the spatial and temporal variability of the optical properties of the Wadden Sea area. Temporal changes in concentrations, absorption and reflectance due to tides and between seasons are examined. Concentration ranges (Chlorophyll 5-50 ug/l, SPM 5-400 mg/l, CDOM(440) 2.5 1/m) and optical differences were large, mainly due to shallowness which leads to constant resuspension of bottom material, but also due to mixing of water from the North Sea with water from various rivers (Ems, Jade, Weser). Spatial patterns in absorption and reflectance have not been studied before in this area. The measurements will increase the calibration accuracy of optical remote sensing models of this area and contribute to the general knowledge of optical properties of tidal areas. First results will be presented of the comparison between processed MERIS images (using the Hydropt algorithm (Van der Woerd and Pasterkamp, 2008) calibrated with measured specific optical properties) and in-situ observed concentrations and spectra. From space the large heterogeneity of the area becomes visible.

DIEL AND SPATIAL VARIABILITY OF PARTICLE SIZE DISTRIBUTION IN THE EASTERN SOUTH PACIFIC

Sciandra, Antoine¹; Stramski, Dariusz²; Marcel, Babin¹; Twardowski, Michael S.³; Carolina, Grob<sup>1

1</sup>Laboratoire d'Océanographie de Villefranche sur mer - CNRS Station Zoologique - BP28 - Chemin du Lazaret, Villefranche sur mer, --, 06234, France; ²Marine Physical Laboratory, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, 92093-0238 , United States; ³Department of Research, WET Labs, Inc., 165 Dean Knauss Dr., Narragansett, Rhode Island, 02882, United States

The particle size distributions (PSDs) were measured on discrete water samples with an electrical resistive particle sizer (Multisizer 3, Beckman Coulter) and an optical particle sizer (Hiac, Pacific Scientific) during the French BIOSOPE cruise along a 7500 km transect in the eastern South Pacific from the Marquesas Islands to the Chilean coast. The PSDs of small particles (less than about 10 µm) obtained with the Multisizer 3 and the PSDs for larger particles (> 4 µm) from Hiac were merged to obtain continuous PSDs within the size range 0.7 - 100 µm. A good agreement was generally observed between the two instruments within the overlapping size range, which provided a basis for merging the data at a particle diameter of about 5 mm. A total of 160 PSDs representing samples from the euphotic oceanic layer allowed us to analyze the spatial and diurnal variability of PSD across different trophic regions explored during the cruise. A common feature for a majority of PSDs is that they can be partitioned into three segments. In the range of submicrometer particles (SMP), the slope of PSD was typically significantly steeper (from -9 to -5) compared to that for larger particles (about -4). The SMP displayed diel variations, especially well-pronounced in the deep chlorophyll maximum layer within the South Pacific Subtropical Gyre. In the 1-4 µm size range, the PSDs showed distinct features associated with plankton populations, which appear clearly as maxima in the particle volume distributions. These features also exhibited diel variations. Flow cytometer measurements and PSD data obtained for isolated species upon sorting suggest that the diel variations in the PSD slope in the submicrometer range and the 1 - 4 µm range can be attributed to cyanobacteria and small-sized eukaryotic phytoplankton populations, respectively. For particles larger than 4 µm, the PSDs were generally more regular in shape, but also displayed diel variations. Our data suggest that the general parameterization of PSD in terms of a single slope over a broad size can be often inadequate for marine environments, including open ocean waters dominated by biological particles. The observed diel variations in PSDs are expected to have ramifications for variability in seawater optical properties.

VARIATION IN ABSORPTION PROPERTIES OF THE EUROPEAN COASTAL WATERS: APPLICATION TO OCEAN COLOR SATELLITE ALGORITHMS.

Tilstone, Gavin¹; Van der Woerd, Hendrik Jan²; Eleveld, Marieke²; Peters, Steef<sup>2

1</sup>Plymouth Marine Laboratory (PML), Prospect Place, West Hoe, Plymouth, Devon, PL1 3DH, United Kingdom; ²Vrije Universiteit Amsterdam De Boelelaan 1087, Amsterdam, --, 1081 HV, Netherlands

We aim to improve the quality of Chlorophyll a (Chla) retrieval in European coastal waters by proper characterization of an optimal IOP set to describe various water types. The absorption properties of phytoplankton (a_ph), non-algal particles (a_NAP) and colored dissolved organic material (a_CDOM) and concentrations of Chla and Total Suspended Material (TSM) were measured at 468 stations in the North Sea from April 2002 to September 2003. Chla varied from 0.2 to 35 mg m^-3, TSM from 0.2 to 75 g m^-3 and a_CDOM(442) varied from 0.02 to 0.26 m^-1. In European coastal areas, Chla was significantly higher along the Dutch coast, TSM along the German Bight and East Anglia, UK coast and a_CDOM was significantly higher in Norwegian waters. A budget was constructed using Chla, TSM and a_CDOM data which indicated that approximately 75% of the stations sampled were Case 2, of which 25 % dominated by a_CDOM, 8% dominated by TSM.Approximately 40% stations had similar proportions of Chla, TSM and a_CDOM(442). We present multiple approaches to categorize the inherent optical properties based on geography, an absorption budget and absorption signatures associated with dominant water masses in the North Sea. For the water masses,a_CDOM(442) and a_NAP(442) regressed against salinity exhibited four distinctive relationships which are associated with the hydrography of the North Sea; a_CDOM dominated waters in the Skagerak originating from Baltic Sea outflow, TSM dominated waters typical of the Continental European Coast, Chla dominated waters associated with the inflow of Atlantic water and Chla-TSM- aCDOM waters representing the mixing of Atlantic, Continental Coastal and Skagerak waters.

Each approach was used to parameterize the semi-analytical remote sensing algorithm HYDROPT. Differences in Chla, TSM, CDOM concentrations between each approach will be presented and compared to products available from standard MERIS, MODIS and SeaWiFS algorithms.

EOF ON CHL, SST AND SEA LEVEL OVER THE MEDITERRANEAN SEA: A CORRELATION ANALYSIS

Volpe, Gianluca¹; Buongiorno Nardelli, Bruno¹; Santoleri, Rosalia<sup>1

1</sup>GOS - ISAC - CNR Via Fosso del Cavaliere 100, Rome, --, 00133, Italy

Different EOF analyses have been performed over chlorophyll-a (CHL), sea surface temperetaure (SST) and Mediterranean Absolute Dynamic Topography (MADT) weekly maps from 1998 to 2006, covering the Mediterranean Sea. EOF analyses require data to be continous in space and time; therefore a Data INterpolating Empirical Orthogonal Functions (DINEOF) analysis was performed over gappy fields to fill in missing data, due to clouds and/or low sampling rates. Standard EOF analysis main results are that seasonality can explain up to 57%, 97% and 70% of the variance of CHL, SST and MADT, respectively. To explain the eventual dependence of one process upon the other, spatial and lagged correlations between different variable EOF modes were computed. As seasonality drives most of the variance in all of the three datasets, first modes from the three variables were highly correlated in time with different time lags. Second modes of variability explain only 7%, 1% and 3% of total variance of CHL, SST and MADT time series, respectively. Nonetheless, especially for CHL and SST, those second modes are unequivocally referred to the joint Gulf of Lions-Ligurian Sea spring bloom, and to the deep water formation dynamics of the Gulf of Lions. Those modes present a maximum correlation at lag of 6 months (r=-0.6). The analysis was repeated using a low-pass filter on climatology-removed data to remove the seasonality and the higher frequency signals. Interannual components were successfully detected. Biological space-time variability was found to be sensitive to circulation changes which were thought to have had a minor or negligible impact.

FIELD CHARACTERIZATION OF THE DAILY VARIABILITY OF THE PARTICULATE BEAM ATTENUATION COEFFICIENT

GERNEZ, Pierre¹; ANTOINE, David²; HUOT, Yannick<sup>2

1</sup>ACRI-st and CNRS-LOV LOV, Villefranche sur mer, --, 06230, France; ²CNRS-LOV, Villefranche sur, mer, 06230, France

The particulate beam attenuation coefficient at 660 nm (cp) is a descriptor of the particulate matter load. In the open ocean, over large spatial scales, cp varies at first order with the phytoplankton biomass. A second order variability in cp is also observed in response to local changes, such as wind events, cloud cover and changes in the bulk particle composition. Furthermore, a daily cycle in cp is associated the daily changes in irradiance.

In situ investigation of the cp daily variability is, however, generally limited to a few days. The development of instrumented moorings allows in situ measurements to be performed at high frequency, over long periods (years) and under varying environmental conditions (trophic state, vertical distribution of the water properties, cloudiness, sea state).

A time series of inherent and apparent optical properties (cp, chlorophyll fluorescence, backscattering coefficient, downward and upward irradiances ) has been collected at an open ocean mooring (BOUSSOLE project) in the North western Mediterranean Sea (60 km offshore Nice, France). All data are simultaneously recorded every 15 minutes at 4 and 9 m depth. This database allows us to characterize the daily variability in cp, with consideration of the physical forcing and the phytoplankton population composition (as described by monthly HPLC analyses). We show seasonal changes linked to the physical and trophic state of the water.

IMAGE-DERIVED AUTOMATED ATMOSPHERIC CORRECTION FOR COASTAL REMOTE SENSING APPLICATIONS

Hou, Weilin ¹; Lee, Zhongping¹; Martinolich, Paul¹; Gould, Rick¹; Arnone, Robert<sup>1

1</sup>Naval Research Laboratory 1009 Balch Blvd, Stennis Space Center, MS, 39529, United States

Coastal oceanic and estuarine environments are important areas for ecological studies, pollution monitor and control, as well as defense and homeland security applications. Research in such areas is complicated by more factors compared to open oceans, not only because of the dynamic nature associated with interactions between land runoff, river discharge, and bottom impacts, but also complications caused by cloud coverage as a result of land-sea aerosol interactions. However, this added challenge can be beneficial under certain conditions and can be used to improve atmospheric correction (Lee et al, 2007). This study presents the initial results of an automated approach to find the proper pairs of in/out shadow pixels for atmospheric correction, and further the derived subsurface properties from the corrected image. Hyperion images from different scenes around Florida are used for the testing of the automated cloud-shadow correction algorithm and retrieval of subsurface properties. Specifically, remote sensing reflectance derived from Hyperion imagery after cloud-shadow correction is compared to in situ measurements. Further, bathymetry data retrieved using Hyperion remote sensing reflectance is shown to match calibrated bathymetry data, which is provided by SHOALS. Retrieved absorption values at selected wavelengths are also in general agreement with field measurements. These results suggest validity as well as portability of this automated cloud-shadow approach when sparse cloud coverage is available. This approach helps to eliminate artificial requirements imposed by other correction methods.

VALIDATION OF HYPERSPECTRAL IMAGE-DERIVED BENTHIC COVER USING TOWED UNDERWATER VIDEO TRANSECTS

Klonowski, Wojciech¹; Lynch, Mervyn¹; Gray, Mark¹; Fearns, Peter<sup>1

1</sup>Curtin University of Technology Kent st, Bentley, --, 6102, Australia

Inversion-based approaches for mapping benthic cover from hyperspectral imagery are becoming increasingly popular, as a result of the promising results they have shown to date. Subsequently these approaches are now being applied to highly diverse and complex ecosystems, however, often without validation of the benthic cover products. In this study, we apply a shallow water reflectance model to hyperspectral imagery captured over the Ningaloo Marine Park, Australia. The model incorporates a bottom reflectance term, which is parameterised by a combination of 3 key benthic habitat classes (sediment, vegetation and coral). A benthic cover map is derived from the retrieved model parameters and is validated with towed underwater video footage. We present the comparison results and discuss the issues involved with validating benthic cover.

RADIATIVE TRANSFER CLOSURE IN THE ST-LAWRENCE GULF AND ESTUARY : ESTIMATION OF THE SPECTRAL BACKSCATTERING FRACTION

Çizmeli, Servet¹; O'Neill, Norman¹; Roy, Suzanne²; Larouche, Pierre³; Yayla, Mehmet<sup>1

1</sup>University of Sherbrooke 2500 Blvd. Université, Sherbrooke, QC, J1K2R1, Canada; ²Institut des Sciences de la Mer de Rimouski / 310 Allée des Ursulines, Rimouski, Québec, G5L3A1, Canada; ³Institut Maurice Lamontagne / 850, route de la Mer C.P. 1000, Mont-Joli, Québec, G5H3Z4, Canada

In order to help solve the problems associated with the estimation of the marine chlorophyll-a concentration from space, assumptions have to be made regarding the magnitude and spectral characteristics of all in-water IOPs (Inhrent Optical Properties) and their relationship with the AOPs (Apparent Optical Properties) measured by the satellite. The AOPs are functions of the IOPs and the IOPs are primarily functions of both the concentration and the optical nature of chlorophyll-a, SPM (Suspended Particulare Matter) and CDOM (Chromophoric Dissolved Organic Matter) in the water column. Radiative transfer simulations offer valuable information when dealing with the remote sensing problem in the optically complex waters of the St. Lawrence gulf and estuary as they reveal the dependency of the AOPs to each optically active IOP. During the bio-optical cruises that were performed in the St. Lawrence gulf and estuary in May 2000 and April 2001, the in-water multispectral reflectance, absorption and attenuation coefficients were measured at 44 stations in total. A radiative transfer closure study was performed using measured absorption and attenuation coefficient spectra and trial families of parameterized backscattering coefficient spectra as inputs. For eachstation visited, 111 simulated reflectance curves were produced where each curve corresponds to a different set of assumed backscattering parameters. An iterative match-up was then performed between the simulated and measured reflectance data. The matching of measured and modelled reflectance spectra represents an iterative radiative transfer closure procedure. This procedure yielded estimates of the bulk spectral backscattering coefficient which compared well with actual in-situ measurements. The iterative approach also allowed the extraction of information on the magnitude and the spectral variability of the backscattering fraction. This method is presented as a simple way of estimating the spectral backscattering coefficient of the water column when only in-situ measurements of spectral reflectance, absorption and attenuation coefficients are available.

COLORS OF RED TIDE

Kishino, Motoaki¹; Nakayama, Ryuta¹; Furuya, Ken<sup>1

1</sup>The University of Tokyo 1-1-1 Yayoi, Bunkyo, Tokyo, --, 113-8657, Japan

Color is an important element in monitoring of red tides.It is recorded using color codes in routine monitoring of HAB events in Japan.However, different color codes are used according to organizing bodies of the monitoring, making inter-comparison among different databases difficult.We developed a method to enable the inter-comparison by converting color codes to CIE (Commision Internationale de l’Eclairage) Chromaticity Diagrams through determining reflectance spectrum of each color code.Two sets of color codes were examined.One was the most widely used one in Japan, “Akashio Kansoku Suishoku Kahdo (Color chart for red tide water)” which was composed of 108 standard colors with 12 hues and 9 chroma saturations, and another was Munsell Color Chart. The method was applied two sets of database acquired from the Seto Inland Sea and Osaka Bay, Japan to elucidate characteristics of colors of red tides.The former database was based on air-born observation. and the latter by ship observations.There was a distinct difference in bothhues and chroma between Seto Inland Sea and Osaka Bay.Colors on the CIE Chromaticity Diagramswere distributed widely from light or dark red to orange in Seto Inland Sea, while closely grayish green in Osaka Bay.Reasons for the differences will be discussed.

SATELLITE BASED ALGAL BLOOM DETECTION IN EUROPEAN WATERS

Park, Young-Je¹; Ruddick, Kevin²; Lacroix, Geneviève<sup>2

1</sup>CSIRO Land and Water Christian Lab., Clunies Ross Street, Acton, Canberra, --, 2601, Australia; ²MUMM-RBINS / Gulledelle 100, Woluwe-St-Lambert, Brussels, 1200, Belgium

An automatic detection of algal blooms (ABs) based on satellite chlorophyll a concentration (Chl) is presented. A threshold map was defined as the 90 percentile of previous years’ data to take account of two factors – regional differences in Chl levels in European waters and possible systematic errors present in satellite chlorophyll data especially in coastal waters. By the relative nature of the threshold, this approach can deal with different water types, which is required for processing European waters.

The detection is based on standard Chl data from MODIS and MERIS. Use of two or more sources is obviously beneficial for better spatial and temporal coverage. Comparison of quasi-coincident observation shows reasonable agreement in clear case 1 waters between the two sensors. However, MODIS Chl estimated by a blue-green band ratio algorithm may not be usable in turbidity dominated waters. Such turbid pixels are identified using a model relationship between the water-leaving radiance at 667 nm and Chl, and removed from the processing chain.

By comparing the daily Chl data with the predefined threshold map, daily AB maps are generated. Recent AB information within a week is added where daily Chl is not available to give a better representation of the spatial extent of the algal bloom.

Maps of AB timing (first day when an AB is detected in a year) and AB magnitude (peak value of Chl in a year), were derived for years 2005-2007. These maps show significant spatial and inter-annual variability. This variability will be briefly explained in relation to light and nutrient availability, and possibly hydrodynamic conditions and sea surface temperature.

OCEAN OPTICS 2007 CLASS PROJECT: INHERENT OPTICAL PROPERTIES OF THE DAMARISCOTTA RIVER ESTUARY: WHAT IS HAPPENING AT THE RIVER-SEA INTERFACE?

Gray, Amanda ¹; Cetinic, Ivona ²; Woods, Sarah ³; Randolph, Kaylan<sup>4

1</sup>University of Washington 1013 NE 40th St, Seattle, WA, 98105-6698, United States; ²University of Southern California, Los Angeles, California, 90089-0371, Afghanistan; ³University of Miami / 4600 Rickenbacker Causeway, Miami, Florida, 33149, United States; ⁴University of Connecticut / 1080 Shennecossett Road, Groton, Conneticut, 06340, United States

Estuaries have characteristically strong environmental gradients, driven by the freshwater input and tidal forcing. Such extreme environmental conditions, especially on the interface between the two water types, result in highly complex optical patterns, due to the dissolved or particulate water constituents present. During June of 2006, hydrographic and optical properties of the water column were measured at two stations in Damariscotta River Estuary. The upper estuary station revealed strong riverine influence, with temperature and salinity driven stratification. Water column profiles of lower estuary station however revealed higher salinity and lower temperature values but with the upper riverine water layer still present at the surface. Both station’s chlorophyll absorption profiles were monotone with a small subsurface maxima that also appeared in the fluorescence signature. Both of the stations had a particulate layer present on the seawater-freshwater interface, showing characteristic backscattering and attenuation signals and backscattering ratio. The particulate signal at the upper-estuary station occurred concurrent with the chlorophyll maxima, while in the lower estuary station the chlorophyll maxima occurred below the particulate signal. Colored dissolved organic matter concentration diminished and the CDOM slope flattened with the depth and distance downriver. The lowest CDOM slope and concentrations were found in the particulate backscattering layer, pointing out once again to the interesting processes in the freshwater-seawater.

POLARIZATION OF THE NEAR-FORWARD LIGHT SCATTERED ON PARTICLES AND A TURBULENT FLOW.

Freda, Wlodzimierz¹; Woods, Sarah²; Bogucki, Darek<sup>2

1</sup>Gdynia Maritime University Morska 81-87, Gdynia, --, 81-225, Poland; ²RSMAS, University of Miami, 4600 Rickenbacker Causeway, Miami, Florida, 33129, United States

The light passing through the sea surface and propagating into deep water is partially polarized. Polarization degree can reach even 0.7 just below the sea surface depending mostly on observation direction, sun direction and state of sea surface (Kattawar et al 1973). In this paper we examine polarization effects in the near-forward direction. From initially polarized light scattered by large particulates (10 to 900 micro) and turbulent flow in the laboratory. The resulting measurements of the four elements of the scattering matrix (upper left corner of the scattering matrix) are calculated for both small angles obtained by means of a diffractometer, and for large angles, obtained by a nephelometer. Our measured values (depolarization ratio equal 0) associated with spherical particulates scattering are consistent with theory (Bohren, Huffman 1983). The turbulent effects on a polarized light beam differ from the particulate contribution, and can be attributed to depolarization by turbulent inhomogeneities.

OCEAN OPTICS 2007 CLASS PROJECT: IN SITU OPTICAL AND RADIOMETRIC AND DATA ACCURACY ASSESSMENT AND OPTICAL CLOSURE

Randolph, Kaylan ¹; Woods, Sarah ²; Cetinic, Ivona³; Gray, Amanda <sup>4

1</sup>University of Connecticut 1080 Shennecossett Road, Groton, CT, 06340, United States; ²University of Miami / 4600 Rickenbacker Causeway, Miami, Florida, 33149, United States; ³University of Southern California / 3616 Trousdale Pkwy, Los Angeles, California, 90089-0371, United States; ⁴University of Washington / 1013 NE 40th St., Seattle, Washington, 98105-6698, United States

Optical closure exercises are pivotal for evaluating the accuracy of water quality remote sensing techniques. Agreement between water-leaving radiance and inherent optical properties (IOPs) is necessary for resolving biogeochemical parameters from space. Relatively high errors have been reported for in situ instruments retrieving upwelling radiance in highly backscattering waters. Optically complex waters prove optimal for testing closure between apparent optical properties (AOPs), IOPs, and analytically measured biogeochemical parameters. A comprehensive suite of IOPs and AOPs were measured with depth for two sampling locations in the Damariscotta River Estuary, Maine on July 13, 2007. Ultimately, the largest percent difference (PD) between measured and modeled radiance reflectance was in the green portion of the spectrum at Station 2, where a 38% difference resulted. Stronger agreement was achieved for Station 1, where a maximum difference of 22% occurred at 660 nm. Neither closure routine meets the requirements of the SeaWIFS Project, for which the maximum acceptable uncertainty is 5%. Sources contributing to the resulting difference could be inaccuracies in radiometric measurements (i.e. sensor tilt) and in IOP measurements. Evaluation of those and other possible sources of error was assessed through instrument intercomparison and an appraisal of the assumptions applied in correction schemes.

TURBULENT OCEANIC FLOW – AN OPTICALLY ACTIVE MEDIUM

Bogucki, Darek¹; Woods, Sarah¹; Freda, Wlodzimierz<sup>2

1</sup>RSMAS, University of Miami 4600 Rickenbacker Causeway, Miami, FL, 33149, United States; ²Gdynia Maritime University/Physics Department/Gdynia, Gdynia, Pomorskie, 81-225 , Poland

Turbulent inhomogeneities of fluid flow have the effect of scattering light into near-forward angles.

In laboratory and in situ experiments we have examined the value and angular dependent contribution of the turbulent scattering coefficient b_turb as a function of turbulence strength. The b_turb can attain values as high as 10 [1/m] for some oceanic conditions such as near the ocean surface and values as low as 0.1 [1/m] at depth.

This ubiquitous presence of turbulent scattering has implications for oceanic measurements as well as for remote sensing applications.

MEASURING ORGANIC CARBON TRANSPORT BY THE MISSISSIPPI RIVER USING OCEAN COLOR REMOTE SENSING

Del Castillo, Carlos E¹; Spiering, Bruce A²; Miller, Richard L<sup>3

1</sup>Johns Hopkins University-APL 11100 Johns Hopkins Rd, Laurel, MD, 20723, United States; ²NASA - Applications, Technology Development, and Transfer Office, Stennis Space Center, Mississippi, 39529, United States; ³Department of Geological Science East Carolina University, Greenville, North Carolina, 27857, United States

We investigated the use of ocean color remote sensing to measure the transport of dissolved organic carbon (DOC), and particulate organic carbon (POC) by the Mississippi River to the Gulf of Mexico. From 2000 to 2008 we recorded surface measurements of DOC, POC, colored dissolved organic matter (CDOM), salinity, and water-leaving radiances during five cruises to the Mississippi River Plume. These measurements were used to develop empirical relationships to derive DOC, CDOM, and salinity from monthly composites of SeaWiFS imagery collected from 1998 through 2005. MODIS 250 m resolution data was used to estimate total suspended sediments (TSS) and POC transport. Our remote sensing estimates of river flow and DOC transport correlated well with USGS data. Our remote sensing estimates and USGS field data showed low variability in DOC concentrations in the river end-member, and high seasonal variability in river flow. Therefore, changes in river flow control the variability in DOC transport, indicating that the remote sensing estimate of river flow is the most critical element of our DOC transport measurement. Remote sensing measurements of TSM were used to estimate POC concentrations using POC-TSS relationships obtained from field samples. Values of DOC and POC transport were combined to estimate total organic carbon transport by the Mississippi River.

PROPOSED NORMALIZATION OF SECCHI DISK DATA FOR ULTRA CLEAR LAKES

Kleppe, John¹; Girdner, Scott<sup>2

1</sup>University of Nevada,Reno 2776 Spinnaker Drive, Reno, NV, 89519, United States; ²Crater Lake National Park, Crater Lake, Oregon, 97604, United States

The Secchi disk may be one of the most controversial instruments used for water clarity measurements. This paper demonstrates that the Secchi disk, if properly applied, can provide accurate, reliable, and inexpensive measurements of water clarity for use by water resources managers. The theory of the Secchi disk is briefly reviewed including some recent work that explains how the Secchi disk disappears in terms of a water modulation transfer function. A major limitation of the routine use of a Secchi disk is that many lakes where measurements are needed may not have the conditions necessary for successful measurements near the solar maximum, i.e., calm water and a bright clear, cloudless sky. This paper proposes a Secchi disk normalization procedure that will allow measurements to be taken at times other than near the time of maximum solar altitude and be normalized to true zenith. This method is an extension of the process proposed by Verschuur in 1997. Verschuur’s method sometimes has been questioned because he interpreted the solar altitude dependence of the Secchi depth to be a simple geometrical phenomenon. Also there are concerns that since Verschuur’s measurements were taken in a lake with small Secchi depths the technique may not be applicable to clear lakes with greatly increased Secchi depths. The Secchi disk normalization procedure presented in this paper was compared to experimental data taken in Crater Lake, Oregon, USA. Simultaneous measurements were taken using an underwater spectroradiometer, a Quantum PAR sensor, a transmissometer, and a standard B/W 20 cm Secchi disk. The measurements were started early in the morning before the sun rose above the edge of the crater and continued until just after the maximum solar altitude.This paper presents a comparison between the Secchi disk theory and the experimental data gathered at Crater Lake,OR.

EFFECTS OF LARGE PARTICLE AND TURBULENT SCATTERING ON WAVEFRONT SENSOR MEASUREMENTS OF THE VOLUME SCATTERING FUNCTION

Woods, Sarah¹; Bogucki, Darek¹; Freda, Wlodek<sup>2

1</sup>Division of Applied Marine Physics, RSMAS, University of Miami 4600 Rickenbacker Causeway, Miami, FL, 33149, United States; ²Physics Department, Gdynia Maritime University, Morska 81-87, Gdynia, Pomorskie, 81-225, Poland

The oceanic volume scattering function (VSF) at near-forward angles is strongly influenced by scattering from large particulates and turbulent inhomogeneities, with the latter dominating at the smallest angles. We obtain laboratory wavefront sensor measurements of the VSF in turbulent fluid flow, which are used to determine the total turbulent scattering coefficient, and are affected by the presence of large particulates. The turbulent flow is well controlled, allowing for acquisition of time series long enough to compute the turbulent kinetic energy (TKE) dissipation rate, lying in the range 10^-8 to 10^-6 m²s^-3 for our setup. We quantify the effect of large particle scattering on the wavefront measured VSF by comparing the VSF derived from wavefront measurements and diffractometer measurements of the turbulent fluid, both with and without particulates (diameter 10 micrometers to 1 millimeter). These measurement derived VSFs are also compared to Rytov theory prediction obtained from the angular autocorrelation of the wavefront measurements. Such quantification of large particle scattering on the VSF in the presence of turbulence is important for singling out the scattering attributed solely to the turbulent fluid flow, allowing for optical characterization of the turbulence. Quantification of the total turbulent scattering is vital for anyone making oceanic measurements of turbulence, the particulate VSF at small angles, or particle size distributions within the water column.

AN INSTRUMENT TO MEASURE THE BACKSCATTERING COEFFICIENT FOR ARBITRARY PHASE FUNCTIONS

Haubrich, David¹; Fry, Edward S.¹; Musser, Joseph A.<sup>1

1</sup>Texas A&M University Texas A&M University, Dept. of Physics, TAMU 4242, College Station, TX, 77843-4242, United States

The backscattering coefficient, which is the integral of the volume scattering function in the backwards direction, is one of the inherent optical properties used in the characterization of water. Current instruments measure the backscattering at the so called “Magic Angle”. This is based on work done by Oishi (1990). This theory assumes that the backscattering coefficient is, to a good approximation, proportional to the signal at the magic angle. Of course, such an assumption guarantees that if there is anything interesting in the water, it will probably be missed.

We have developed an instrument to directly measure the backscattering coefficient for arbitrary phase functions; the instrument is suitable for in situ applications.

We present the theoretical framework, instrument design, and calibration data. We show that our instrument has the necessary resolution to measure backscattering coefficients that range from those found in the cleanest sea waters to those typically found in biologically-rich coastal-type waters. We will also show how increased absorption due to particulate matter in the water affects our instrument.

Our instrument is approximately 30cm long and has a diameter of 15cm. The laser is housed inside the instrument, while an umbilical cord connects it to the power supply and the detectors outside. Excluding these, the weight of the instrument is below 1kg. In order to avoid noise from other light sources such as sunlight, the laser is pulsed at a specified frequency in the kHz range and the signal is locked to those pulses using a lock-in amplifier.

Our instrument provides the ocean optics community with what we believe is the first device to directly measure the backscattering coefficient b_b for any phase function.

SOLAR IRRADIANCE IN CORAL REEFS: CDOM AS A PHOTOPROTECTIVE BARRIER FROM UVR

Ayoub, Lore Michele¹; Coble, Paula G¹; Hallock, Pamela<sup>1

1</sup>University of South Florida 140 Seventh Avenue South, Saint Petersburg, FL, 33701, United States

Experiments have demonstrated that corals and reef-dwelling foraminifera bleach more readily when exposed to short wavelength, high energy solar radiation (blue, violet and ultraviolet; λ ~ 280 - 490 nm). In seawater, colored dissolved organic matter (CDOM), also called gelbstoff, preferentially absorbs these shorter wavelengths, which consequently bleach and degrade the CDOM. Alteration and destruction of watershed and coastal wetlands have reduced natural sources of CDOM that are tidally flushed into reefal waters. We have measured incident and in situ ultraviolet radiation (UVR) and absorption of UVR at various reefs in the Florida Keys that differ in distance from shore and in the degree of anthropogenic development, intact mangrove hammock, and CDOM-rich Everglades-sourced Florida Bay water of the adjacent shoreline. Onshore-offshore transects from a mangrove-lined canal, across a patch reef and reef margin to deep (blue) water, showed a steady decrease in absorption due to CDOM. Absorption due to CDOM at 320 nm (a_g320) was significantly higher and less variable, and spectral slope of CDOM absorption in the UVB range, S_{(280-312 nm)}, was significantly lower and less variable at reefs associated with intact shorelines and at reefs with consistent CDOM sources. Attenuation coefficient for downwelling irradiance, K_d, was calculated from in situ downwelling irradiance (E_d) (BIC Biospherical Instruments^©) at 3 wavelengths in the UV range (305, 330 and 380 nm) and PAR (400-700 nm). K_{d 305} and K_{d 330} were significantly higher at inshore reefs than offshore reefs. These results can provide guidance to resource managers regarding management of CDOM sources to reefal waters, including preservation of tidal wetlands, ground-truthing inherent optical properties, and basis for developing a new algorithm for UVR and for a_{g UV} based on satellite-derived measurements of a_{g PAR}.

INTER-COMPARISON OF SEAWIFS/MODIS COASTAL WATERS ATMOSPHERIC CORRECTION ALGORITHMS

Jamet, Cedric¹; Loisel, Hubert¹; Feng, Hui²; Zibordi, Guiseppe<sup>3

1</sup>LOG/ULCO MREN, 32 avenue Foch, Wimereux, --, 62930, France; ²UNH/OPAL, Morse Hall, Durham, New Hampshire, 03824, United States; ³JRC, SAI-ME TP272, Ispra, Italy, 21020, Italy

Studying ocean optical properties in coastal waters from remote-sensing measurements is a difficult task. Indeed, contrary to the open ocean, it is not possible to consider that the water-leaving luminance (Lw) is negligeable in the near-infrared wavelengths (NIR). Several atmospheric correction algorithms (AC) for coastal waters have been developed for the past ten years for SeaWiFS and MODIS sensors. This study aims to inter-compare differents AC and to estimate their capability to deal with the presence of a NIR Lw. We used three algorithms, developed by Stumpf et al. (2004), which is the SeaWiFS/MODIS standard algorithm, by Ruddick et al. (2000) and by Hu et al. (2000). The SeaWiFS and MODIS L2 products obtained by these algorithms are compared to in-situ measurements of the normalized Lw collected in French Guyana, in the Channel and to AERONET-OC ground-based stations (east coast of the USA, Adriatic Sea). The accuracies of the retrieved normalized Lw in the visible and the NIR are studied and compared. Moreover, the hypothesis of the algorithms are discussed with the help of the in-situ data.

FLOW CYTOMETRY MEETS SPECTROPHOTOMETRY: SPECIFIC ABSORPTION SIGNATURES IN PHYTOPLANKTON COMMUNITIES

van Dijk, Mark A.¹; Hoogveld, Hans L.¹; Simis, Stefan G.H.²; Kromkamp, Jacco C.<sup>3

1</sup>NIOO-KNAW Centre for Limnology Rijksstraatweg 6, Nieuwersluis, --, 3631 AC, Netherlands; ²Finnish Institute of Marine Research, Erik Palménin Aukio 1, Helsinki, Etelä-Suomen lääni, 00560, Finland; ³NIOO-KNAW Centre for Estuarine and Marine Ecology, Korringaweg 7, Yerseke, Zeeland, 4401 NT, Netherlands

Remote sensing of plankton biomass and carbon fixation in oceanic and inland waters requires accurate knowledge of the optical properties of the phytoplankton. Particularly, the chlorophyll-specific absorption coefficient, a^*_Chl [m² (mg Chla)^-1] is an essential parameter because it constitutes the link between biomass and light absorption. In eutrophic inland and coastal waters the red absorption peak of Chla near 675 nm is used to retrieve chlorophyll a biomass. The retrieval algorithms often apply a constant value of a^*_Chl, even though the coefficient has been shown to be highly variable in the marine environment and in cultures. Up to date, this variability has not been assessed for eutrophic inland and coastal waters, potentially resulting in erroneous estimates of biomass and productivity.

The Chla-specific absorption depends on species composition and environmental conditions. Variability in a^*_Chl can be explained by variation in the intracellular pigment composition and the pigment packaging effect. In the red part of the spectrum most variability appears to be attributable to the package effect. Natural plankton communities consist of many species, making it difficult to determine whether the changes in a^*_Chl­ are caused by changes in the species composition or by the physiological state of the plankton. The present work combines flow-cytometric sorting with spectrophotometry to study the optical properties of selected subpopulations within the phytoplankton community. This technique may be particularly useful in eutrophic coastal and inland waters, where large heterogeneity in environmental conditions, and thus in phytoplankton composition can occur within the scale of regional observations. Flow cytometry is used to isolate selected dominant populations from natural waters, for which optical properties are then determined. Chl a-specific absorption spectra for these subpopulations are presented, as well as some limitations of the method.

BIO-OPTICAL SPECTRAL MODELLING OF UNDERWATER IRRADIANCE AND PRIMARY PRODUCTION IN THE BLACK SEA

Churilova, Tatyana¹; Suslin, Vyacheslav<sup>2

1</sup>Institute of Biology of the Southern Seas, National Academy of Sciences 2 Nakhimov Ave., Sevastopol, --, 99011, Ukraine; ²Marine Hydrophysical Institute, National Academy of Sciences, 2 Kapitanskay str., Sevastopol, Crimea, 99000, Ukraine

Light absorption by all suspended particles, phytoplankton, non-algal particles and coloured dissolved organic matter measured during last ten years in various regions of the Black Sea and in different seasons has been parameterized. Modelling of photosynthetic available radiance (PAR) has taken into account seasonal and regional peculiarities in light absorption features of all in-waters optically active components. The PAR modelling has been based on SeaWiFS and MODIS information about incident on sea surface PAR, subsurface temperature, subsurface chlorophyll a concentration based on which chlorophyll profile was retrieved. Analysis of sensitivity of the PAR model to variability of each variable has shown dissolved organic matter is the main optically active in-water component, which effects relatively stronger the spectral feature of under water irradiance. The spectral model of primary production (PP) is based on physiological parameters of phytoplankton – on light absorption coefficient and quantum yield of photosynthesis, which depend on environmental factors namely temperature, quantity and quality of available radiance and nutrient availability. The effect of seasonal variability in environmental factors and in species composition of phytoplankton community on efficiency of absorption of ambient light and finally on PP has been analyzed.

AN INTERCOMPARISON OF BIO-OPTICAL TECHNIQUES FOR DETECTING PHYTOPLANKTON FUNCTIONAL TYPES FROM SPACE

Brewin, Robert John William¹; Lavender, Samantha²; Hardman-Mountford, Nick³; Barciela, Rosa<sup>4

1</sup>University of Plymouth A504 Portland Square, University of Plymouth, Drake Circus, Plymouth, --, PL4 8AA, United Kingdom; ²University of Plymouth / ARGANS Limited, A403 Portland Square, University of Plymouth, Drake Circus, Plymouth, Devon, PL4 8AA, United Kingdom; ³Plymouth Marine Laboratory, Prospect Place , Plymouth, Devon, PL1 3DH , United Kingdom; ⁴Met Office, FitzRoy Road, Exeter, Devon, EX1 3PB, United Kingdom

The process of photosynthesis is a fundamental part of the carbon cycle, and improving models of the flux of atmospheric carbon dioxide to the oceans depends on the accurate depiction of phytoplankton community abundance, distributions and physiology, which ultimately dictates the drawdown of CO₂. Developing and enhancing this understanding on a regional and global scale is, therefore, an essential step towards improving estimates of the atmospheric flux of CO₂ to the oceans. Satellite remote sensing of ocean colour is currently the only way of measuring synoptically wide-area ocean properties such as phytoplankton abundance, and recent bio-optical and ecological methods have been established that use satellite data to differentiate between certain phytoplankton functional groups (PFTs) e.g. Alvain et al. (2005); Uitz et al. (2006); Devred et al. (2006); Hirata et al. (accepted); Raitsos et al. (2008). These techniques have been developed using either inherent optical properties (IOPs) or apparent optical properties (AOPs), and thus vary significantly in their approach. These techniques have been applied to a long-term ocean colour merged data set from the GlobColour project and validated using a composite in situ dataset in order to establish a verified approach. Future work will compare CO₂ flux variation hindcasts, produced by the FOAM-HadOCC 3D physical model with coupled biology, in order to better understand the contribution of different PFTs to global CO₂ flux variability. The ultimate aim being a better understanding of how the oceans influence CO₂ fluxes and how it’s likely to change in the future.

PARTICULATE ORGANIC CARBON (POC) IN THE NORTH ATLANTIC: SPATIAL AND TEMPORAL VARIABILITY

Stramska, Malgorzata<sup>1

1</sup>San Diego State University 6505 Alvarado Rd., Ste. 206, San Diego, --, CA 92120, United States

We have used the recently derived remote sensing algorithm (Stramski et al., 2008) to estimate surface concentration of POC in the North Atlantic. Our estimates are based on Level 3 standard mapped images (SMI) of daily normalized water leaving radiances at 443, 490, and 555 nm with a nominal 9 km x 9 km resolution from the ten years of SeaWiFS ocean color. In this presentation we discuss characteristic patterns of seasonal and geographic POC variability. We demonstrate that the large scale interannual trends in POC concentration are relatively small. POC variability is compared with patterns in primary productivity (PP) and export (PE). Mixed layer depth (MLD) climatology and optical depth estimates are used to derive estimates of POC reservoir in the North Atlantic surface waters.

EXPERIMENTAL VALIDATION OF A LASER PULSE TIME HISTORY MODEL

Dalgleish, Fraser R.¹; Mazel, Charles²; Giddings, Thomas³; Shirron, Joseph³; Caimi, Frank M.¹; Britton, Walter B.¹; Wan, Yueting¹; Towle, Jonathan P.²; Glynn, James M.<sup>2

1</sup>Harbor Branch Oceanographic Institution, Ft. Pierce, FL, 34946, United States; ²Physical Sciences Inc. 20 New England Business Center, Andover, MA, 01810, United States; ³Metron, Inc., Reston, VA, 20190, United States

We are conducting equipment development, experimental, and computational work in support of a prototype pulsed laser line scan imaging system. Use of a pulsed rather than CW laser creates the potential for gating the return to reduce backscatter and increase signal-to-noise ratio, and for determining the range to each pixel to assemble a 3-D scene representation. The pulsed laser in combination with novel beam scanning and detection optics are being tested at a large purpose-built imaging test tank facility at the Florida Atlantic University/Harbor Branch Oceanographic Institution campus. A computational model that incorporates both system hardware and water optical property parameters has been developed to aid in performance prediction and evaluation of alternative design parameters. The model evaluates the contributions from both backscatter and target reflection to predict the photon flux arriving at the receiver as a function of time. The model includes the option to use either a fully analytical small angle scattering approximation or a Monte Carlo code.

We conducted a series of experiments in the imaging test facility to validate the computational model for predicting pulse time history. The pulsed laser operates at 532 nm at a 357 kHz repetition rate with 7 ns pulse width. Scattering was varied by the addition of Maalox and optical properties were measured with an ac-9 meter. Parameters such as receiver aperture and source-receiver separation were systematically varied and a series of pulse time histories were recorded with a high bandwidth photomultiplier tube at a 10 GHz sampling rate. The measured and modeled results were then compared. Discrepancies were evaluated to determine if the cause lay with the model or the experiment. The model is proving to be a good predictor of pulse behavior and a useful tool to support pulsed laser imager system development.

SOME WAYS TO DEAL WITH THE HIGH VARIABILITY OF OCEAN COLOR IN COASTAL AREAS

Loisel, Hubert¹; Mériaux, Xavier ¹; Lubac, Bertrand²; Chami, Malik<sup>3

1</sup>LOG CNRS-Université du Littoral 32 avenue Foch, Wimereux, --, 62930, France; ²University of Southern Mississippi , Hattiesburg, MS, MS 39406-0001 , United States; ³LOV, Villefranche-sur-mer, Villefranche-sur-mer, 06230, France

Accurate assessment of the different in water bio-optical components from ocean color measurements in coastal areas, is largely controlled by i) our ability to understand and to account for the origin of the variability of the remote sensing reflectance (R_rs), and ii) the realism of the parameterizations used between the inherent optical properties (IOPs) and the biogeochemical component (BC). Regional approaches are generally adopted to limit the impact of such variability through the development of algorithms specifically build from data collected in the studied regions. However, while such regional algorithms may reduce the variability in the IOPs-BC relationships, they are highly dependent on the data set used for their development. Moreover, even for a local area and a given season, the regional algorithms may also be largely inadequate due to the numerous high frequency processes occurring in coastal waters. Here, we discuss the potential offered by an other approach based on classification techniques which should allow to improve the performance of the inversion. This study is based on R_rs, IOPs, and BC measurements performed in various coastal environments (eastern English Channel, southern North sea, Black sea, and nearshore French Guyana waters). We specifically show that the particulate backscattering to scattering ratio is a key parameter in such inversion procedure.

REMOTE SENSING OF CHLOROPHYLL A CONCENTRATION AND COLOR DETRITAL MATTER ABSORPTION IN THE BLACK SEA: A SEMI-EMPIRICAL APPROACH FOR THE SEA-VIEWING WIDE FIELD-OF-VIEW SENSOR (SEAWIFS)

Suslin, Vyacheslav¹; Sosik, Heidi²; Churilova, Tatyana ³; Korolev, Sergei<sup>1

1</sup>Marine Hydrophysical Institute 2 Kapitanskaya str., Sevastopol, --, 99000, Ukraine; ²Woods Hole Oceanographic Institution, Woods Hole, MA, 02543-1049, United States; ³Institute of Biology of the Southern Seas, National Academy of Science, Sevastopol, Crimea, 99011, Ukraine

We describe an algorithm for retrieval of chlorophyll a concentration and colored detrital matter absorption in the Black Sea from SeaWiFS-derived normalized water-leaving radiances. A specialized approach is needed for the Black Sea, because of the optical complexity of the waters and overlying atmosphere. The algorithm is based on a simple physical model of seawater optical properties formulated in terms of two spectral ratios of normalized water-leaving radiance in SeaWiFS bands 3-5. Parameters of the model are selected empirically with a regional tuning procedure that presumes distinct water types for shelf and deep water regions of the Black Sea. In situ observations of chlorophyll a concentration and to a lesser extent of colored detrital matter absorption are used parameterize and evaluate the algorithm. We provide some preliminary assessments of sensitivity to critical parameters. In comparison to chlorophyll a concentration retrievals from the standard global empirical algorithm for SeaWiFS (OC4), our approach provides unbiased estimates across 100-fold range in values and produces much more realistic seasonality. In situ observations in the Black Sea remain sparse and more data is required for further evaluation. Our approach may be valuable for a variety of optically complex waters and we demonstrate this with preliminary application to other shelf and semi-enclosed seas.

ON THE USE OF OPTICAL REMOTE SENSING TO ASSESS PHYTOPLANKTON DYNAMICS

Manca Zeichen, Marta¹; Finoia, Maria Grazia¹; Barale, Vittorio<sup>2

1</sup>ICRAM Central Institute for Applied Marine Research via di Casalotti, 300, Rome, --, 00166, Italy; ²Institute for Environment and Sustainability, Joint Research Centre, European Commission , Ispra , Varese, 21020, Italy

The present study highlights the strategic importance of exploiting historical optical observations within a pelagic Marine Protected Area (MPA) located in the north-western Mediterranean Sea. Ocean colour data collected by orbital remote sensing, and in particular seven years (1998-2004) of Sea-viewing Wide Field-of-view Sensor (SeaWiFS) data, were analysed in order to monitor the concentration of chlorophyll-like pigments (chl), and to document its space and time variability. Phytoplankton dynamics in this area, where the Pelagos International Marine Mammals Sanctuary was established in 1999, support a large biomass of primary (and secondary) producers, as well as a highly developed food web, which includes a sizeable standing population of fin whales, Balaenoptera physalus, and various other marine mammals. Mean chl images were generated for consecutive 10-day periods, to ensure (quasi-) continuous coverage of the area of interest, and a Principal Component Analysis (PCA) performed over the whole dataset. The chl surface patterns were used to trace the seasonal upwelling events recurring every year in the sanctuary. Such events produce blooming episodes that play a critical role in sustaining the food web of the Sanctuary. However, they may differ in peak timing, spatial distribution as well as chl levels. The study of chl, as retrieved synoptically from SeaWiFS data, has helped to increase our knowledge about the phytoplankton dynamics that sustain a large marine mammal population in this unique MPA.

COMBINED USE OF AN AUV AND HYPERSPECTRAL IMAGER TO MAPPING SEA-SURFACE AND MACROALGAE

Hovland, Erlend Kjeldsberg¹; Johnsen, Geir¹; Moline, Mark<sup>2

1</sup>Trondheim Biological Station, NTNU, Bynesvegen 46, Trondheim, --, 7049, Norway; ²Center for Marine and Coastal Sciences, California Polytechnic State University,, San Luis Obispo, California, CA 93407, United States

Monitoring and areal coverage of sea water constituents and benthic organisms is presently of interest in marine monitoring and surveillance. Human and climate related activity have motivated the marine science community to come up with new approaches to monitor and map objects of interest on a synoptic scale. Furthermore, the need for area coverage, concentration and biomass of objects of interests is gaining interest in modern monitoring systems. We present data of an AUV equipped with optical and acoustic sensors (L_u, E_d, Chl a, cDOM, turbidity, side scanning sonar and ADCP) to map constituents in the water masses and mapping the seafloor (covering 25 000 m²) to estimate kelp forest coverage versus substrate. In addition, photosynthetic activity of Fucus distichus (Phaeophyceae) has been measured for 24 hours at 5 minute intervals, and used as a model organism for diurnal photosynthetic activity in the kelp forest mapped by the AUV. The average E_K (light saturation index) was 68 µmol m^-2 s^-1, indicating medium lightacclimated algae. SCUBA based photos of substrate and seaweed species has been used for further identification of species. These two measurements are combined to also estimate primary productivity in these areas. In addition, hyperspectral imager data (water-leaving radiance from 300-800 nm with a bandwidth of 1 nm) was taken from a mountain facing the area of the AUV/SCUBA survey to measure different watermasses and optical characteristics during summertime melting period in Isfjorden, Svalbard.

OPTICAL AND PHYSICAL PROPERTIES OF COASTAL WATER AND THEIR RELATIONS TO RADAR (ASAR) DATA – A CASE STUDY OF MUUGA BAY, GULF OF FINLAND

Sipelgas, Liis¹; Uiboupin, Rivo<sup>1

1</sup>Tallinn University of Technology Akadeemia tee 21B, Tallinn, --, 12618, Estonia

A field study of optical and physical properties in Muuga Bay, Gulf of Finland was performed on 30 May, 2007. In one of the studied stations traces of ballast water were visible on the water surface. An Advanced Synthetic Aperture Radar (ASAR) image was received and analysed from the same area. The vertical profiles of the absorption and attenuation coefficient together with the temperature and salinity profiles were measured in 13 stations. The concentrations of oil products, chlorophyll a, coloured dissolved organic matter, and suspended particulate matter were determined from water samples. The spatial distribution of temperature, salinity, and optically active substances indicated four distinct areas: the southern coastal area with saline, cold and chlorophyll a poor upwelling water, western coast of the bay with warmer and chlorophyll a richer surface water and open water dominated by higher concentrations of coloured dissolved organic matter, and Muuga harbour where the water had a high concentration of suspended particulate matter and chlorophyll a which caused stronger light attenuation and a thinner euphotic layer compared to the other parts of the bay. Regression analysis showed that the absorption coefficient at 676 nm correlated well with the chlorophyll a concentration and the scattering coefficient at 555 nm correlated with the suspended matter concentration in Muuga Bay. The correlation coefficient between ASAR data and oil products was 0.71 although the concentration of oil products was relatively low (0.01–1.72 ppm).

INVERSION OF INHERENT OPTICAL PROPERTIES FROM REFLECTANCE DATA IN ATLANTIC, EUROPEAN SHELF SEA AND BALTIC WATERS.

Moore, Gerald¹; Kratzer, Susanne<sup>2

1</sup>University of Plymouth Drake Circus, Plymouth, --, PL4 8AA, United Kingdom; ²Department of Systems Ecology, University of Stockholm, Stockholm, Stockholm, SE-106 91, Sweden

A simple inversion model to determine the inherent optical properties (IOP), of absorption and scattering from ocean reflectance data is described. Backscatter is decoupled from absorption data and is given a fixed spectral slope. The absorption is described by a simple two component model using a fixed combined slope for CDOM/ detrital absorption, and a variable slope linear model for phytoplankton absorption. The model is parameterized using the NOMAD data set, and validated using independent data from the Atlantic Meriodonal Transect (AMT), the Baltic and the North Sea. The model uses data from the 443nm,490nm,510nm, and 5