METHODS FOR THE SURFACE REFLECTANCE RETRIEVAL FROMCHRIS/PROBADATA OVER LANDAND INLAND WATERS

摘要

The Compact High Resolution Imaging Spectrometerrn(CHRIS) on board the Project for On–Board Autonomyrn(PROBA) platform system provides the first high spa-tialrnresolution hyperspectral/multiangular remote sensingrndata from a satellite system, what represents a new sourcernof information for Earth Observation purposes. Whenrndealing with the retrieval of surface reflectance from suchrnkind of hyperspectral data, a radiative transfer approachrnis commonly preferred. However, since CHRIS 2003rnand 2004 data present reported calibration problems inrnseveral bands, especially in the near–infrared region, arnstandard atmospheric correction based on radiative trans-ferrnmodels should not be performed. A dedicated at-mosphericrncorrection algorithm for CHRIS/PROBA datarnover land is presented in this work. It consists in therncombination of radiative transfer and empirical line ap-proachesrnto atmospheric correction, in order to retrievernsurface reflectance images free from both the atmo-sphericrndistortion and artifacts due to mis–calibration.rnThe atmospheric optical parameters and the updated setrnof calibration coefficients are obtained jointly in an au-tonomousrnprocess, without the need for any ancillaryrndata. Results from the application of the algorithm tornCHRIS/PROBA data from the two ESA Spectra bAR-raxrnCampaign (SPARC) held at the Barrax study site (LarnMancha, Spain) in 2003 and 2004 are presented in thisrnwork, focusing on the validation of the final surface re-flectancernusing in–situ measurements acquired simulta-neouslyrnto PROBA overpasses. Besides, the first ver-sionrnof an atmospheric correction module for inland wa-ters,rnwhich is currently under development, is also pre-sented,rnas well as the first results obtained from its appli-cationrnto data from the Rosarito reservoir. The potentialrnof CHRIS/PROBA data for Earth observation purposes isrnshown.