Aster/TIR vicarious calibration activities in the last 11 years

Since March 2000, the project science team for the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) onboard NASA´s Terra satellite has conducted vicarious calibration (VC) experiments periodically to verify the onboard calibration (OBC) of ASTER thermal infrared (ASTER/TIR) bands. In the present paper, 287 matchup data obtained from ten experimental sites by three organizations are analyzed. The radiance difference of OBC and VC shows almost no correlation with surface temperature and precipitable water vapor at each experimental site, but shows some dependence on the type of the experimental site. For example, the OBC-VC comparisons at Cold Springs Reservoir (NV) which is a small water body shows some bias due to the strayhght effect of ASTER/TIR. The comparisons at Lake Kussharo covered by snow also show some bias maybe because of an extrapolation effect of ASTER radiometric calibration. The comparisons at Mauna Loa lava flows show a large deviation due to non- uniformity of surface temperature caused by the rough surface. Except for these cases, the results show that the latest version of radiometric calibration coefficients (version 3.x) for ASTER/TIR has been keeping the designed accuracy (1 K for the temperature range of 270 to 320 K).