Determination of land surface reflectance using the AATSR dual-view capability

[摘要] In this study, a method is presented to retrieve the surface reflectanceusing the radiances measured at the top of the atmosphere for the two viewsprovided by the Advanced Along-Track Scanning Radiometer (AATSR). In the first step,the aerosol optical depth (AOD) is obtained using the AATSR dual-viewalgorithm (ADV) by eliminating the effect of the surface on the measuredradiances. Hence the AOD is independent of surface properties and can thusbe used in the second step to provide the aerosol part of the atmosphericcorrection which is needed for the surface reflectance retrieval. The methodis applied to provide monthly maps of both AOD and surface reflectance attwo wavelengths (555 and 659 nm) for the whole year of 2007.

The results are validated versus surface reflectance provided by theAERONET-based Surface Reflectance Validation Network (ASRVN). Correlationcoefficients are 0.8 and 0.9 for 555 and 659 nm, respectively. The standarddeviation is 0.001 for both wavelengths and the absolute error is less than0.02. Pixel-by-pixel comparison with MODIS (Moderate Resolution ImagingSpectrometer) monthly averaged surface reflectances show a good correlation(0.91 and 0.89 for 555 and 659 nm, respectively) with somewhat higher values(up to 0.05) obtained by ADV over bright surfaces. The difference betweenthe ADV- and MODIS-retrieved surface reflectances is smaller than ±0.025for 68.3% of the collocated pixels at 555 nm and 79.9% of thecollocated pixels at 659 nm. An application of the results over Australiaillustrates the variation in the surface reflectances for different landcover types.

The validation and comparison results suggest that the algorithm can besuccessfully used for both the AATSR and ATSR-2 (which has characteristicssimilar to AATSR) missions, which together cover a 17-year period ofmeasurements (1995–2012), as well as a prototype for the Sea and LandSurface Temperature Radiometer (SLSTR) planned to be launched in the fallof 2015 onboard the Sentinel-3 satellite.

[学科分类] 几何与拓扑