Frouin, Robert: Scripps Institution of Oceanography, UCSD (Project Lead)
Project Funding:
2011 - 2014
NRA: 2010 NASA: NPP Science Team for Climate Data Records
Funded by NASA
Abstract:
We propose to continue a measurement program previously developed as part of the NASA SIMBIOS project for evaluation of satellite-derived ocean color, with emphasis on the coastal zone. Our objective is to gather from platforms of opportunity, e.g., merchant ships and research vessels, a data set of concomitant normalized water-leaving radiance and aerosol optical thickness, i.e., the basic ocean color variables, in varied oceanic and atmospheric environments. Such a data set is needed to check vicariously the radiometric calibration of satellite ocean color sensors and verify whether satellite retrievals of normalized water-leaving radiance are within acceptable uncertainty limits and, eventually, to adjust atmospheric correction schemes.
The data will be collected using 25 dedicated, portable SIMBADA radiometers that measure both variables in typical spectral bands of satellite ocean-color sensors. These above-water radiometers have been designed specifically for ocean color evaluation, and the measurement concept has been thoroughly tested. The processing algorithms and software will be improved, especially to correct for residual polarization by the water

body and to deal with highly turbid waters. Measurements will be made in open and coastal/estuarine waters and situations of non-absorbing and absorbing aerosols. The processed data, after proper quality control, will be distributed to satellite project offices.
Comparisons between surface measurements and satellite estimates from EOS and NPP/NPOESS sensors (i.e., MODIS, VIIRS, including SeaWiFS) will be made, after correction for differences in spectral bands and angular geometry. The discrepancies between the two types of data will be examined. Not only SIMBADA data collected during the course of the project will be used in the comparisons, but also data collected during previous years. The SIMBADA data will also be used to check the radiometric calibration of the satellite sensors while they operate in orbit. The analysis will provide information on the accuracy of satellite retrievals of normalized water-leaving radiance, an understanding of the discrepancies between satellite and surface data, and algorithms that reduce the discrepancies. The results will contribute to improved and consistent multi-year ocean-color data sets from various satellite sensors for understanding ocean biogeochemistry and its role in Earth's climate.
More details may be found in the following project profile(s):
