Abstract
The main objective of the SENTINEL-3 mission is to measure sea surface topography, sea and land surface temperature, and ocean and land surface colour with high accuracy and reliability to support ocean forecasting systems, environmental monitoring and climate monitoring. The mission will provide data continuity for the ERS, Envisat and SPOT satellites. The SENTINEL-3 mission will be jointly operated by ESA and EUMETSAT to deliver operational ocean and land observation services. Sentinel-3 will make use of multiple sensing instruments to accomplish its objectives. Two of them, OLCI (Ocean and Land Colour Imager) and SLSTR (Sea and Land Surface Temperature Radiometer), are optical sensors designed to provide a continuity with Envisat's MERIS and AATSR instruments. OLCI is based on the opto-mechanical and imaging design of MERIS instrument, i.e. a push-broom imaging spectrometer with five cameras and a total swath width of 1270 km. The acquisition is made for a spatial sampling of 300m and in 21 spectral bands from 0.4 to 1.02 microns. SLSTR is based on the design of AATSR instrument, i.e. a conical scanning imaging radiometer employing the along track scanning dual view technique for a total swath of 1420km nadir (and 750km backward). The acquisition is made for a spatial sampling of 500m (VIS-SWIR) and 1000m (MWIR, TIR) and in 9 spectral bands from 0.55 to 12 microns. The first Sentinel-3A satellite will be launched in late 2015. During the commissioning phase lasting approximately 5 months, in-orbit calibration and validation activities will be conducted. Instrument will be recalibrated and recharacterized in-orbit particularly using on-board devices which include diffusers (OLCI, SLSTR) and black body (SLSTR). We present here the vicarious calibration methods that will be used in order to validate the OLCI and SLSTR radiometry for the reflective bands. It is expected to check the calibration over Rayleigh scattering, sunglint, desert sites, Antarctica, and tentatively deep convective clouds. For this, tools have been developed and/or adapted (S3ETRAC, MUSCLE). Based on these matchups, it will be possible to provide an accurate checking of absolute and interband calibrations, the trending correction, the behavior within field-of-view calibration, and more generally this will provide an evaluation of the radiometric consistency for various type of targets. The cross-calibration will also be checked with many other instruments such as MERIS, AATSR, MODIS, as well as Sentinel-2.
Manuscript
Sentinel-3 OLCI/SLSTR - Validation of the Radiometric Calibration for Optical Sensors
The main objective of the SENTINEL-3 mission is to measure sea surface topography, sea and land surface temperature, and ocean and land surface colour with high accuracy and reliability to support ocean forecasting systems, environmental monitoring and climate monitoring. The mission will provide data continuity for the ERS, Envisat and SPOT satellites. The SENTINEL-3 mission will be jointly operated by ESA and EUMETSAT to deliver operational ocean and land observation services. Sentinel-3 will make use of multiple sensing instruments to accomplish its objectives. Two of them, OLCI (Ocean and Land Colour Imager) and SLSTR (Sea and Land Surface Temperature Radiometer), are optical sensors designed to provide a continuity with Envisat's MERIS and AATSR instruments. OLCI is based on the opto-mechanical and imaging design of MERIS instrument, i.e. a push-broom imaging spectrometer with five cameras and a total swath width of 1270 km. The acquisition is made for a spatial sampling of 300m and in 21 spectral bands from 0.4 to 1.02 microns. SLSTR is based on the design of AATSR instrument, i.e. a conical scanning imaging radiometer employing the along track scanning dual view technique for a total swath of 1420km nadir (and 750km backward). The acquisition is made for a spatial sampling of 500m (VIS-SWIR) and 1000m (MWIR, TIR) and in 9 spectral bands from 0.55 to 12 microns. The first Sentinel-3A satellite will be launched in late 2015. During the commissioning phase lasting approximately 5 months, in-orbit calibration and validation activities will be conducted. Instrument will be recalibrated and recharacterized in-orbit particularly using on-board devices which include diffusers (OLCI, SLSTR) and black body (SLSTR). We present here the vicarious calibration methods that will be used in order to validate the OLCI and SLSTR radiometry for the reflective bands. It is expected to check the calibration over Rayleigh scattering, sunglint, desert sites, Antarctica, and tentatively deep convective clouds. For this, tools have been developed and/or adapted (S3ETRAC, MUSCLE). Based on these matchups, it will be possible to provide an accurate checking of absolute and interband calibrations, the trending correction, the behavior within field-of-view calibration, and more generally this will provide an evaluation of the radiometric consistency for various type of targets. The cross-calibration will also be checked with many other instruments such as MERIS, AATSR, MODIS, as well as Sentinel-2.