[ARCHIVE] Black Sea Monthly and Daily Reprocessed Surface Chlorophyll Concentration from Multi Satellite observations + SeaWiFS daily climatology
'''This product has been archived'''
For operationnal and online products, please visit https://marine.copernicus.eu
'''Short description:'''
The Global Ocean Satellite monitoring and marine ecosystem study group (GOS) of the Italian National Research Council (CNR), in Rome, distributes Level-4 product including the daily interpolated chlorophyll field with no data voids starting from the multi-sensor (MODIS-Aqua, NOAA-20 VIIRS, NPP-VIIRS, Sentinel3A-OLCI), the monthly averaged chlorophyll concentration for the multi-sensor and climatological fields, all at 1 km resolution. The chlorophyll (Chl) product is obtained combine two different regional algorithms. The first is a band-ratio algorithm (Zibordi et al., 2015) that computes Chl as a function of the slope of Rrs values at two wavelengths (490 and 555 nm). The second one is a Multilayer Perceptron (MLP) neural net based on Rrs values at three individual wavelengths (490, 510 and 555 nm) that features interpolation capabilities helpful to fit data non-linearities. The merging scheme (Kajiyama et al., 2018) has been designed to use the B/R algorithm and the MLP neural net in waters exhibiting lower and higher optical complexity, respectively. The interpolated gap-free Level-4 Chlorophyll concentration is estimated by means of a modified version of the DINEOF algorithm by GOS (Volpe et al., 2018). DINEOF is an iterative procedure in which EOF are used to reconstruct the entire field domain. As first guess, it uses the SeaWiFS-derived daily climatological values at missing pixels and satellite observations at valid pixels. Monthly L4 datasets are the time averages of the L3 fields (including standard deviation and the number of observations). A SeaWiFS daily climatology has also been computed using the latest L2 NASA reprocessing (R2018.0) and providing reference for the calculation of Quality Indices (QI) for NRT/DT products.
'''Processing information:'''
Multi-sensor product is constituted by MODIS-AQUA, NOAA20-VIIRS, NPP-VIIRS and Sentinel3A-OLCI. For consistency with NASA L2 dataset, BRDF correction was applied to Sentinel3A-OLCI prior to band shifting and multi sensor merging. Single sensor NASA Level-2 data are destriped and then all Level-2 data are remapped at 1 km spatial resolution using cylindrical equirectangular projection. Afterwards, single sensor Rrs fields are band-shifted, over the SeaWiFS native bands (using the QAAv6 model, Lee et al., 2002) and merged with a technique aimed at smoothing the differences among different sensors. This technique is developed by The Global Ocean Satellite monitoring and marine ecosystem study group (GOS) of the Italian National Research Council (CNR, Rome). Then geophysical fields (i.e. chlorophyll) are estimated via state-of-the-art algorithms for better product quality. Level-4 includes monthly time averages, the daily-interpolated fields and climatological chlorophyll field. Time averages are computed on the delayed-time data. The interpolated product starts from the L3 products at 1 km resolution. At the first iteration, DINEOF procedure uses, as first guess for each of the missing pixels the relative daily climatological pixel. A procedure to smooth out spurious spatial gradients is applied to the daily merged image (observation and climatology). From the second iteration, the procedure uses, as input for the next one, the field obtained by the EOF calculation, using only a number of modes: that is, at the second round, only the first two modes, at the third only the first three, and so on. At each iteration, the same smoothing procedure is applied between EOF output and initial observations. The procedure stops when the variance explained by the current EOF mode exceeds that of noise. The entire data set is consistent and processed in one-shot mode (with an unique software version and identical configurations). For the climatology Rrs data are derived from the latest SeaWiFS NASA reprocessing (R2018.0) and converted to chlorophyll concentrations with the same algorithm as the one used for other L4 and/or L3 products.
'''Description of observation methods/instruments:'''
Ocean colour technique exploits the emerging electromagnetic radiation from the sea surface in different wavelengths. The spectral variability of this signal defines the so-called ocean colour which is affected by the presence of phytoplankton.
'''Quality / Accuracy / Calibration information:'''
A detailed description of the calibration and validation activities performed over this product can be found on the CMEMS web portal.
'''Suitability, Expected type of users / uses:'''
This product is meant for use for educational purposes and for the managing of the marine safety, marine resources, marine and coastal environment and for climate and seasonal studies.
'''Dataset names:'''
*dataset-oc-bs-chl-multi-l4-chl_1km_monthly-rep-v02
*dataset-oc-bs-chl-multi-l4-interp_1km_daily-rep
*dataset-oc-bs-chl-seawifs-l4-chl_1km_daily-climatology-v02
'''Files format:'''
*CF-1.4
*INSPIRE compliant
'''DOI (product) :'''
Date(s) Date(s) |
|
Contact(s) Contact(s) |
Rosalia SANTOLERI
(
OC-CNR-ROMA-IT
)
Gianluca VOLPE ( OSI-CNR-ROMA-IT ) Emanuele BÖHM ( OC-CNR-ROMA-IT ) Javier CONCHA ( OC-CNR-ROMA-IT ) Simone COLELLA ( OC-CNR-ROMA-IT ) |
Source Source |
E.U. Copernicus Marine Service Information |
Lineage Généalogie |
The myOcean products depends on other products for production or validation. The detailed list of dependencies is given in ISO19115's aggregationInfo (ISO19139 Xpath = "gmd:MD_Metadata/gmd:identificationInfo/gmd:aggregationInfo[./gmd:MD_AggregateInformation/gmd:initiativeType/gmd:DS_InitiativeTypeCode/@codeListValue='upstream-validation' or 'upstream-production']") |
Constraints Contraintes |
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Spatial informations Informations géographiques |
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