TOWARDS CALIBRATION OF SENTINEL 3 DATA: VALIDATION OF SATELLITEDERIVED SST AGAINST IN SITU COASTAL OBSERVATIONS OF THE PORTUGUESE MARINE WATERS

摘要

Validation of future Sentinel-3 SLSTR data in the Eastern Atlantic Ocean was analysed here through a comparison of satellite-derived STT against in situ mooring buoys observations. SST_(skin) retrieved from IR satellite radiometers onboard ERS 1-2, Envisat, and Aqua, and concurrent SST_(bulk) measured with 14 buoy thermistors located at ~1m depth were used to assess the statistical relationships between these datasets, with 20038 matchups spanning from 1996 to 2015. As expected, results showed consistency between SST_(skin) and SST_(bulk), exhibiting a correlation coefficient on the order of 98 %. Biases of both (A)ATSR and MODIS for day-time suggest a warmer satellite skin retrieval of + 0.15o and + 0.06o, respectively. For the night-time dataset, biases of - 0.25o and - 0.17o for (A)ATSR and MODIS, respectively, indicate cooler skin retrievals and reveal an inversion of the upper ocean thermic gradient. The RMSE′s found were 0.53o for (A)ATSR and 0.41o for MODIS datasets.