Land Surface Temperature Retrieval By Integrating MODIS Data Onboard Terra And Aqua Satellites

Land surface temperature is a key parameter of surface physical processand plays an important significance to the energy balance in the world, whichaffects the energy exchange between land surface and atmosphere. It haswidely been applied to meteorology, geology, hydrology and zoology,especially the study on water content of soil, monitoring of forest fire.Atmospheric correction is an important part to retrieve land surfacetemperature. Based on the knowledge of atmospheric radiative transfer, themodeling scheme is ensured, and the Moderate spectral resolutionatmospheric Transmittance algorithm and computer model is selected tomodel the atmosphere. The band respond functions of Terra/Aqua MODIS aretaken into account to simulate the effects of view angle, solar zenith and watercolumn of atmosphere on retrieval of land surface temperature. Thesesimulation shows that the atmospheric transmission is decreasing with theviewing angle from 0 degree to 65 degree, and the changes to two satellitesare the same. While change of the radiant temperature is about 5K from 0degree to 65 degree, and it is flat before 30 degree than after 30 degree. Thewater column changes from 10% to 100%, and the transmission and radianttemperature are linearly decreasing with the water column. The change ofsolar zenith affects differently the surface-reflected solar beam term andsurface-reflected solar irradiance. With the solar zenith angle increases, thesolar beam at the surface level decreases, but the downward solar diffuseirradiance may increase in some situations.With higher spectral resolution and time resolution, MODIS data are fittedto measure the wide range of land surface temperature and its changes. Thealgorithm on retrieval of land surface temperature is based on day/nightalgorithm, which is suggested by Wan and Li. Land surface temperature isretrieved by MODIS data on Terra satellite during day and night. Now, theMODIS is not only being carried on the Terra, but being carried on the Aqua.The feasibility of retrieval of land surface temperature with MODIS data onTerra and Aqua satellites at the same time is our object in the study. From thesimulation of MODIS data onboard Terra and Aqua satellites, the radiancechanges are the same with the change of viewing angle, solar zenith angle andatmospheric profile. Therefore, the idea on retrieval of land surfacetemperature by MODIS data onboard Terra and Aqua satellites is feasible.To validate the retrieval algorithm by MODIS data onboard Terra andAqua satellites, the retrieval process of the day/night algorithm is investigatedduring this study. Terra-MODIS data at 11:50 on 16 August 2004,Aqua-MODIS data at 14:10 on 17 August 2004 and at 03:50 on 18 August2004 are selected to retrieve LST. At the same time, the field data of QinghaiLake in the Qinghai province are measured. The retrieved result ofTerra-MODIS data at 11:50 on 16 August 2004 and Aqua-MODIS data at14:10 on 17 August 2004 has a difference of 0.35K to the field data, theretrieved result of Terra-MODIS data at 11:50 on 16 August 2004 andAqua-MODIS data at 03:50 on 18 August 2004 has a difference of 1.6K to thefield data.