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SeaWiFS-derived products in the Baltic Sea: performance analysis of a simple atmospheric correction algorithm

100%

Bulgarelli B., Melin F., Zibordi G.

Oceanologia

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2003

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tom 45

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nr 4

The accuracyan alysis of an approximate atmospheric correction algorithm for the processing of SeaWiFS data has been investigated for the Baltic Sea. The analysis made use of theoretical radiances produced with the FEM radiative transfer code for representative atmosphere-water test cases. The studysho wed uncertainties in the determination of the aerosol optical thickness at 865 nm and of the ˚Angstr¨om exponent lower than ±5% and ±10%, respectively. These results were confirmed bythe analysis of 59 match-ups between satellite-derived and in situ measurements for a site located in the central Baltic. Because of the relativelyhig h yellow substance absorption, often combined with the slanted solar illumination, the retrieval of the water-leaving radiance in the blue part of the spectrum appeared to be highlyd egraded, to the extent that almost no correlation was found between retrieved and simulated values. Better results were obtained at the other wavelengths. The accuracyin the estimation of the remote sensing reflectance ratio R35 decreased with diminishing chlorophyll a concentration and increasing yellow substance absorption, ranging between ±7% and ±47%. The propagation of R35 uncertainties on chlorophyll a estimation was quantified. Keeping the same atmosphere-water conditions, the atmospheric correction scheme appeared sensitive to seasonal changes in the Sun zenith.

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Comparison of in situ and satellite ocean color determinations of particulate organic carbon concentration in the global ocean

86%

Swirgon M., Stramska M.

Oceanologia

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2015

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tom 57

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nr 1

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Spectral effects in bio-optical control on the ocean system

86%

Sathyendranath S., Platt T.

Oceanologia

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2007

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tom 49

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nr 1

The influence of phytoplankton on the spectral structure of the submarine irradiance field is reviewed. The implications for the ocean system of the spectral response by phytoplankton to the ambient light field are discussed. For example, it provides the basis for retrieval of phytoplankton biomass by visible spectral radiometry (ocean-colour remote sensing). In the computation of primary production, the results of spectral models differ in a known and systematic manner from those of non-spectral ones. The bias can be corrected without risk of incurring additional random errors. The models in use for phytoplankton growth, whether based on available light or absorbed light, whether expressed in terms of chlorophyll or carbon, are shown all to conform to the same basic formalism with the same parameters. Residual uncertainty lies less with the models than with the parameters required for their implementation. The submarine light field and the spectral characteristics of phytoplankton carry latent information on phytoplankton community structure. Differences in spectral response by different functional types of phytoplankton are small but significant. Optical considerations limit the maximum phytoplankton biomass that can be sustained in a given surface mixed layer. Moreover, the upper bound on the biomass depends on the spectral response of the dominant phytoplankton taxa. As a result, an optical control exists in the mixed layer that tends to resist extreme excursions of the biomass and also to maintain biodiversity in the phytoplankton.

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Comparison of primary productivity estimates in the Baltic Sea based on the DESAMBEM algorithm with estimates based on other similar algorithms

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Stramska M., Zuzewicz A.

Oceanologia

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2013

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tom 55

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nr 1

5

Spatio-temporal variability in the Brazil-Malvinas Confluence Zone (BMCZ), based on spectroradiometric MODIS-AQUA chlorophyll-a observations

72%

Telesca L., Pierini J. O., Lovallo M., Santamaria-del-Angel E.

Oceanologia

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2018

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tom 60

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nr 1

The Brazil–Malvinas Confluence Zone (BMCZ) is characterized by high environmental variation, which could be reflected in several optical types of water, from one containing only phytoplankton and sea water to other optically more complex. In this paper, we analyze the spatio-temporal variability of the Chlorophyll-a detected by the ocean color sensor (CHLAsat) in BMCZ in order to understand its environmental variability. We use the MODIS-Aqua CHLAsat monthly composites imagery from 2002 to 2015, and applied two statistical methods: the correlogram-based robust periodogram to identify, over a broad spectrum of temporal, the most significant periodicities, and the pixel gradient distribution to study the spatial-temporal gradients within the BMCZ and variations over the continental shelf and coastal waters. Our results point out to the predominance of the annual cycle over most of the investigated area, although an area from latitude 37°S in direction NE, alongshore of Uruguay to Brazil, evidences interannual periodicities, possibly related to variations in the discharge of the Rio de la Plata associated with the El Niño phenomena. The ocean color spectroradiometric signature in terms of pixel gradient presents a relatively high variability (∼0.0 to 0.65 mg m−3); in particular the high values of the pixel gradient correspond to saline front of the estuarine system of Rio de la Plata, and to the strip of the platform that extends along the isobaths of 80 m (coast of Uruguay), especially in the center and south of the study area.

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Validation of SeaWiFS and MODIS Aqua-Terra aerosol products in coastal regions of European marginal seas

72%

Melin F., Zibordi G., Carlund T., Holben B. N., Stefan S.

Oceanologia

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2013

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tom 55

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nr 1

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Two models for absorption by coloured dissolved organic matter (CDOM)

72%

Schwarz J. N., Kowalczuk P., Kaczmarek S., Cota G. F., Mitchell B. G., Kahru M., Chavez F. P., Cunningham A., McKee D., Gege P., Kishino M., Phinney D. A., Raine R.

Oceanologia

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2002

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tom 44

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nr 2

The standard exponential model for CDOM absorption has been applied to data from diverse waters. Absorption at 440 nm (ag440) ranged between close to zero and 10 m−1, and the slope oft he semilogarithmic absorption spectrum over a minimum range of400 to 440 nm (s440) ranged between <0.01 and 0.04 nm−1. No relationship was found between ag440 or s440 and salinity. Except in the southern Baltic, s440 was found to have a broad distribution (0.0165 ± 0.0035), suggesting that it should be introduced as an additional variable in bio-optical models when ag440 is large. An alternative model for CDOM absorption was applied to available high quality UV-visible absorption spectra from the WisGla river (Poland). This model assumes that the CDOM absorption spectrum comprises distinct Gaussian absorption bands in the UV, similar to those ofb enzene. Five bands were fit to the data. The mean central energy ofal l bands was higher in early summer (E ∼7.2, 6.6, 6.4, 6.2 and 5.5 eV or 172, 188, 194, 200 and 226 nm) than in winter. The higher energy bands were found to decay in both height and width with increasing salinity, while lower energy bands broadened with increasing salinity. s440 was found to be correlated with shape parameters of the bands centred at 6.4 and 5.5 eV. While the exponential model is convenient for optical modelling and remote sensing applications, these results suggest that the Gaussian model offers a deeper understanding ofc hemical interactions affecting CDOM molecular structure.

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Algorithms for the remote sensing of the Baltic ecosystem (DESAMBEM). Part 2: Empirical validation

58%

Darecki M., Ficek D., Krezel A., Ostrowska M., Majchrowski R., Wozniak S. B., Bradtke K., Dera J., Wozniak B.

Oceanologia

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2008

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tom 50

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nr 4

509-538

This paper is the second of two articles on the methodology of the remote sensing of the Baltic ecosystem. In Part 1 the authors presented the set of DESAMBEM algorithms for determining the major parameters of this ecosystem on the basis of satellite data (see Woźniak et al. 2008 – this issue). That article discussed in detail the mathematical apparatus of the algorithms. Part 2 presents the effects of the practical application of the algorithms and their validation, the latter based on satellite maps of selected Baltic ecosystem parameters: the distributions of the sea surface temperature (SST), the Photosynthetically Available Radiation (PAR) at the sea surface, the surface concentrations of chlorophyll a and the total primary production of organic matter. Particular emphasis was laid on analysing the precision of estimates of these and other parameters of the Baltic ecosystem, determined by remote sensing methods. The errors in these estimates turned out to be relatively small; hence, the set of DESAMBEM algorithms should in the future be utilised as the foundation for the effective satellite monitoring of the state and functioning of the Baltic ecosystem.

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On the use of a simple primary productivity model to assess the skill of a physical ocean model

58%

Kantha L., Carniel S., Clayson C. A., Sclavo M.

Oceanological and Hydrobiological Studies

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2011

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tom 40

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nr 2

10

Diffusive component of the vertical flux of particulate organic carbon in the North polar Atlantic

58%

Stramska M.

Oceanologia

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2006

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tom 48

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nr 4

The diffusive component of the vertical flux of particulate organic carbon (POC) from the surface ocean layer has been estimated using a combination of the mixed layer model and ocean color data from the SeaWiFS satellite. The calculations were carried out for an example location in the north polar Atlantic centered at 75◦N and 0◦ E for the time period of 1998–2004. The satellite estimates of surface POC derived using a regional ocean color algorithm were applied as an input to the model driven by local surface heat and momentum fluxes. For each year of the examined period, the diffusive POC flux was estimated at 200-m depth from April through December. The highest flux is generally observed in the late fall as a result of increased heat loss and convectional mixing of surface waters. A relatively high diffusive POC flux is also observed in early spring, when surface waters are weakly stratified. In addition, the model results demonstrate significant interannual variability. The highest diffusive POC flux occurred in 1999 (about 4500 mg m−2 over the 9-month period). In 1998 and 2002 the estimated flux was about two orders of magnitude lower. The interannual variability of the diffusive POC flux is associated with mixed layer dynamics and underscores the importance of atmospheric forcing for POC export from the surface layer to the ocean’s interior.

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Some optical properties of surface waters in the north-western Tropical Atlantic

58%

Krezel A., Kamieniecki M.

Oceanologia

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1992

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tom 32

Ograniczanie wyników

SeaWiFS-derived products in the Baltic Sea: performance analysis of a simple atmospheric correction algorithm

Comparison of in situ and satellite ocean color determinations of particulate organic carbon concentration in the global ocean

Spectral effects in bio-optical control on the ocean system

Comparison of primary productivity estimates in the Baltic Sea based on the DESAMBEM algorithm with estimates based on other similar algorithms

Spatio-temporal variability in the Brazil-Malvinas Confluence Zone (BMCZ), based on spectroradiometric MODIS-AQUA chlorophyll-a observations

Validation of SeaWiFS and MODIS Aqua-Terra aerosol products in coastal regions of European marginal seas

Two models for absorption by coloured dissolved organic matter (CDOM)

Algorithms for the remote sensing of the Baltic ecosystem (DESAMBEM). Part 2: Empirical validation

On the use of a simple primary productivity model to assess the skill of a physical ocean model

Diffusive component of the vertical flux of particulate organic carbon in the North polar Atlantic

Some optical properties of surface waters in the north-western Tropical Atlantic