scholarly journals In situ autonomous optical radiometry measurements for satellite ocean color validation in the Western Black Sea

Ocean Science ◽  
2015 ◽  
Vol 11 (2) ◽  
pp. 275-286 ◽  
Author(s):  
G. Zibordi ◽  
F. Mélin ◽  
J.-F. Berthon ◽  
M. Talone
Keyword(s):  
Black Sea ◽  
Ocean Color ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
In Situ Data ◽  
Infrared Imager ◽  
Color Data ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Satellite Ocean Color

Abstract. The accuracy of primary satellite ocean color data products from the Moderate Resolution Imaging Spectroradiometer on-board Aqua (MODIS-A) and the Visible/Infrared Imager/Radiometer Suite (VIIRS) is investigated in the Western Black Sea using in situ measurements from the Gloria site included in the ocean color component of the Aerosol Robotic Network (AERONET-OC). The analysis is also extended to an additional well-established AERONET-OC site in the northern Adriatic Sea characterized by optically complex coastal waters exhibiting similarities to those observed at the Gloria site. Results from the comparison of normalized water-leaving radiance LWN indicate biases of a few percent between satellite-derived and in situ data at the center wavelengths relevant for the determination of chlorophyll a concentrations (443–547 nm, or equivalent). Remarkable is the consistency between the annual cycle determined with time series of satellite-derived and in situ LWN ratios at these center wavelengths. Contrarily, the differences between in situ and satellite-derived LWN are pronounced at the blue (i.e., 412 nm) and red (i.e., 667 nm, or equivalent) center wavelengths, confirming difficulties in confidently applying satellite-derived radiometric data from these spectral regions for quantitative analysis in optically complex waters.

scholarly journals In situ autonomous optical radiometry measurements for satellite ocean color validation in the Western Black Sea

2014 ◽  
Vol 11 (6) ◽  
pp. 3003-3034 ◽  
Author(s):  
G. Zibordi ◽  
F. Mélin ◽  
J.-F. Berthon ◽  
M. Talone
Keyword(s):  
Black Sea ◽  
Ocean Color ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
In Situ Data ◽  
Infrared Imager ◽  
Color Data ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Satellite Ocean Color

Abstract. The accuracy of primary satellite ocean color data products from the Moderate Resolution Imaging Spectroradiometer on-board Aqua (MODIS-A) and the Visible/Infrared Imager/Radiometer Suite (VIIRS), is investigated in the Western Black Sea using in situ measurements from the Gloria site included in the Ocean Color component of the Aerosol Robotic Network (AERONET-OC). The analysis is also extended to an additional well-established AERONET-OC site in the northern Adriatic Sea characterized by optically complex coastal waters exhibiting similarities with those observed at the Gloria site. Results from the comparison of normalized-water leaving radiance LWN indicate biases of a few percent between satellite derived and in situ data at the center-wavelengths relevant for the determination of chlorophyll a concentration (443–547 nm, or equivalent). Remarkable is the consistency among the annual cycle determined with time series of satellite-derived and in situ LWN ratios at these center-wavelengths. Contrarily, the differences between in situ and satellite-derived LWN are pronounced at the blue (i.e., 412 nm) and red (i.e., 667 nm, or equivalent) center-wavelengths, suggesting difficulties in confidently applying satellite-derived radiometric data from these spectral regions for quantitative analysis in optically complex waters.

Regional empirical algorithm for an improved retrieval of chlorophyll a concentrations in the Black Sea using Sentinel 3 ocean color data

2021 ◽  
Author(s):  
Violeta Slabakova ◽  
Snejana Moncheva ◽  
Nataliya Slabakova ◽  
Nina Dzembekova
Keyword(s):  
Remote Sensing ◽  
Chlorophyll A ◽  
Black Sea ◽  
Ocean Color ◽  
The Black Sea ◽  
Ocean Color Remote Sensing ◽  
Color Data ◽  
Cubic Polynomial ◽  
Polynomial Formulation

<p>The Black Sea is an extraordinarily complex water body for ocean color remote sensing, as it belong to Case 2 waters, which are characterized by relatively high absorption by Colored Dissolved Organic Matter (CDOM) while the concentration of non-pigmented particulate matter does not co-vary in a predictable manner with chlorophyll <em>a</em> . The optical complexity of the Black Sea is the reason why the standard bio-optical algorithms developed for Case 1 waters, are the source of large uncertainties (of the order of hundreds of percent) of chlorophyll <em>a</em> concentration in the coastal and shelf regions. In the framework of ESA contract “BIO-OPTICS FOR OCEAN COLOR REMOTE SENSING OF THE BLACK SEA - Black Sea Color” we developed empirical ocean color algorithm for chlorophyll<em> a </em>retrieval from Sentinel 3A/OLCI primary ocean color products using the <em>in situ </em>reference bio-optical datasets collected in the Black Sea in the period 2012-2019. Results obtained from the assessment of operational S3A/OLCI chlorophyll products, highlighted and confirmed that the specific regional algorithm is essential for the Black Sea. The coefficients of the regional algorithm were derived from the regression of log-transformed pigment concentrations and remote sensing reflectance ratio at 490nm and 560 nm with determination coefficient R<sup>2</sup> =0.88 and number of samples N=186. The algorithm predicts chlorophyll a values using a cubic polynomial formulation. The result of assessment of the regional chlorophyll <em>a</em> product against independent in situ measurements from the data utilized for algorithm development, showed relatively high accuracy (31.7%), fewer underestimations (MPD=-9.2%) and a good agreement (R<sup>2</sup>=0.66) between datasets indicating that the regional algorithm is more effective in reproducing the  pigment concentration in the Black Sea waters in comparison to the standard Sentinel 3A/OLCI algorithms. Our analysis revealed the importance of providing regional algorithms strictly required to suit the peculiar bio-optical properties featuring this basin. However, this requires collection of accurate<em> in situ </em>measurements in the different parts of the Black Sea. The validity of the reported empirical algorithm obviously depends on the size of the dataset used for its development. The Black Sea waters vary at a basin level due to the sub-regional features, environmental factors and seasonal variability, consequently the presented regional algorithm might have a limited generalization capability. Clearly, more<em> in situ</em> data with improved spatial and temporal coverage are critically needed for further calibration and validation of the ocean color products in the Black Sea.</p>

scholarly journals Assessment of Applicability of Satellite-Derived Ocean Color Data for Studying Variability of Total Suspended Matter in the Surface Layer of the Deep Part of the Black Sea

2020 ◽  
Vol 27 (5) ◽  
Author(s):  
A. S. Kukushkin ◽  
V. V. Suslin ◽  
Keyword(s):  
Surface Layer ◽  
Black Sea ◽  
Suspended Matter ◽  
Temporal Variability ◽  
Ocean Color ◽  
Total Suspended Matter ◽  
The Black Sea ◽  
Backscattering Coefficient ◽  
Color Data

Purpose. Studies of spatial-temporal variability of total suspended matter are necessary for understanding the biochemical processes which form and support stable functioning of a marine ecosystem. The aim of the work is to assess applicability of satellite data for studying total suspended matter variability in the surface layer of the deep part of the Black Sea. Methods and Results. Application of the regression analysis yielded the linear regression equations that unite the in situ measurements of the total suspended matter concentrations in the surface layer in the northeastern (June, 2005–2015) and western (November, 2016, 2017 and December, 2017) deep sea areas, and the regional satellite products (the particulate backscattering coefficient, the absorption coefficient of colored detrital matter and the chlorophyll a concentration). Based on the measured and calculated data arrays, the maps of the total suspended matter concentrations in the surface layer of the northeastern Black Sea were constructed. The interannual changes in the in situ measured concentrations of the total suspended and lithogenic matters, as well as in the quasi-synchronous satellite regional products (the light absorption coefficient of colored detrital matter at 490 nm and the particulate backscattering coefficient at 555 nm) in June, 2005–2015 were considered. High total suspended matter concentrations were noted in 2012, just when extreme growth of the coccolithophorid population was observed in the Black Sea. The correlation coefficients were used to evaluate whether the relation between the total suspended matter concentration and the individual analyzed parameters was fast. Conclusions. Spatial distributions of the measured and calculated total suspended matter contents showed satisfactory agreement. In course of the whole observation period, difference between the values of the measured and calculated total suspended matter concentrations was on average 6–23 %. Possibility of application of the satellite-derived ocean color data for studying spatial-temporal variability of the total suspended matter content is shown.

scholarly journals A Generalization of the TRIX trophic index to the Adriatic Sea basin

2016 ◽  
Author(s):  
Emanuela Fiori ◽  
Marco Zavatarelli ◽  
Nadia Pinardi ◽  
Cristina Mazziotti ◽  
Carla Rita Ferrari
Keyword(s):  
Time Series ◽  
Adriatic Sea ◽  
Simulated Data ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
In Situ Data ◽  
Trophic Index ◽  
Scaling Parameters ◽  
Italian Legislation

Abstract. The Marine Strategy Framework Directive is pushing for new methodological approaches in order to protect the marine environment more effectively. The trophic index TRIX was developed by Vollenweider in 1998 for the coastal area of Emilia-Romagna (northern Adriatic Sea), and was exploited by Italian legislation to characterize the trophic state of coastal waters. In order to implement TRIX in different areas and for different time periods, we developed a methodology for the generalization of the index changing the scaling parameters. We compared the TRIX index calculated from in situ data ("in situ TRIX") with the corresponding index simulated with a coupled physics and biogeochemical numerical model ("model TRIX") implemented in the overall Adriatic Sea. The comparison between in situ and simulated data was carried out for a data time series in the Emilia-Romagna coastal strip. This study demonstrates the compatibility of the model with the in situ TRIX and the necessity to have time series longer than 10 years to evaluate properly the scaling parameters. The model TRIX is finally calculated for the whole Adriatic Sea showing trophic index differences across the Adriatic coastal areas.

scholarly journals Response to Temperature of a Class of In Situ Hyperspectral Radiometers

2017 ◽  
Vol 34 (8) ◽  
pp. 1795-1805 ◽  
Author(s):  
Giuseppe Zibordi ◽  
Marco Talone ◽  
Lukasz Jankowski
Keyword(s):  
Temperature Coefficient ◽  
Spectral Range ◽  
Ocean Color ◽  
Temperature Coefficients ◽  
The Core ◽  
Photodetector Array ◽  
Color Data ◽  
Response To Temperature ◽  
Satellite Ocean Color

AbstractThe response to temperature of sample hyperspectral radiometers commonly used to support the validation of satellite ocean color data was characterized in the 400–800-nm spectral range. Measurements performed in the 10°–40°C interval at 5°C increments showed mean temperature coefficients varying from −0.04 × 10−2 (°C)−1 at 400 nm to +0.33 × 10−2 (°C)−1 at 800 nm, which are largely explained by the temperature coefficient of the photodetector array constituting the core of the sensor. Overall, the results indicate the possibility of applying temperature corrections with an uncertainty of approximately 0.03 × 10−2 (°C)−1 for the class of hyperspectral radiometers investigated in the study.

Evaluation of ocean color data processing schemes for VIIRS sensor using in-situ data of coastal AERONET-OC sites

2013 ◽  
Author(s):  
S. Ahmed ◽  
A. Gilerson ◽  
S. Hlaing ◽  
A. Weidemann ◽  
R. Arnone ◽  
...  
Keyword(s):  
Data Processing ◽  
Ocean Color ◽  
In Situ Data ◽  
Color Data
Sign in / Sign up

Export Citation Format

Share Document