HR: 0830h
AN: B21E-0758    [PDF]
TI: Validation of the MODIS Land-Surface Temperature Products with Temperature and Radiance-based Methods
AU: * Wan, Z
EM: wan@icess.ucsb.edu
AF: University of California, ICESS, Santa Barbara, CA 93106-3060 United States
AU: Zhang, Y
EM: zhang@icess.ucsb.edu
AF: University of California, ICESS, Santa Barbara, CA 93106-3060 United States
AU: Zhang, Q
EM: qzhang@icess.ucsb.edu
AF: University of California, ICESS, Santa Barbara, CA 93106-3060 United States
AB: A major field campaign was conducted in Railroad Valley, NV, in June 2003. Ground-based measurements were made in the clear-sky days from June 26 to 30. Sky radiance and surface-leaving TIR radiance in sunshine and shadow conditions were measured with a Bomem TIR spectroradiometer. Diurnal surface temperatures were measured with four TIR radiometers. Six radio sounding balloons were launched in the period of clear-sky days to measure the atmospheric temperature and water vapor profiles. MODIS Airborne Simulator (MAS) data were acquired in a daytime flight and a nighttime flight on June 27. An excellent match between the measured spectral sky radiance and the radiance calculated with atmospheric radiative transfer code MODTRAN4.0 based on the measured atmospheric profiles provides a solid evidence of the good quality of both the TIR spectroradiometer and the radiative transfer code. The measured surface-leaving TIR radiance in sunshine and shadow conditions were used to retrieve playa surface spectral emissivity by a sun-shadow method. The band-averaged emissivities calculated from the retrieved spectral emissivity agree within 0.005 with those used in the MODIS split-window LST algorithm for the site. Terra and Aqua MODIS 1km LST products were validated with a temperature-based method using the LSTs measured by the TIR radiometers at nights. This method is limited by the spatial variation in LSTs, which is obviously shown in the day and night MAS images. The LST products were also validated in day and night conditions with a radiance-based method, which is based on the MODTRAN code, measured surface emissivity and atmospheric profiles. The LST accuracies are better than 1K in all seven Aqua cases where zenith viewing angles are up to 56\deg, and in four of six Terra cases. The LST accuracy is better than 1.5K in the remaining two Terra cases with viewing angles at 54\deg and 60\deg. The accuracy of nighttime LSTs at viewing angles within 47\deg is better than 0.5K in four Aqua cases and two Terra cases. The MODIS LST products have been validated, most within 1K, in more than 40 clear-sky cases in the wide ranges of surface temperature and atmospheric conditions in 2000-2003.
DE: 0400 Biogeosciences
DE: 1600 GLOBAL CHANGE (New category)
DE: 1640 Remote sensing
SC: Biogeosciences [B]
MN: 2003 Fall Meeting