A mono-window algorithm for retrieving land surface temperature from Landsat TM data and its application to the Israel-Egypt border region

Remote sensing of land surface temperature (LST) from the thermal band data of Landsat Thematic Mapper (TM) still remains unused in comparison with th e extensive studies of its visible and near-infrared (NIR) bands for variou s applications. The brightness temperature can be computed from the digital number (DN) of TM6 data using the equation provided by the National Aerona utics and Space Administration (NASA). However, a proper algorithm for retr ieving LST from the only one thermal band of the sensor still remains unava ilable due to many difficulties in the atmospheric correction. Based on the rmal radiance transfer equation, an attempt has been made in the paper to d evelop a mono-window algorithm for retrieving LST from Landsat TM6 data. Th ree parameters are required for the algorithm: emissivity, transmittance an d effective mean atmospheric temperature. Method about determination of atm ospheric transmittance is given in the paper through the simulation of atmo spheric conditions with LOWTRAN 7 program. A practicable approach of estima ting effective mean atmospheric temperature from local meteorological obser vation is also proposed in the paper when the in situ atmospheric profile d ata is unavailable at the satellite pass, which is generally the case in th e real world especially for the images in the past. Sensitivity analysis of the algorithm indicates that the possible error of ground emissivity, whic h is difficult to estimate, has relatively insignificant impact on the prob able LST estimation error deltaT, which is sensible to the possible error o f transmittance delta iota (6) and mean atmospheric temperature deltaT(a). Validation of the simulated data for various situations of seven typical at mospheres indicates that the algorithm is able to provide an accurate LST r etrieval from TM6 data. The LST difference between the retrieved and the si mulated ones is less than 0.4 degreesC for most situations. Application of the algorithm to the sand dunes across the Israel-Egypt border results in a reasonable LST estimation of the region. Based on this LST estimation, spa tial variation of the interesting thermal phenomenon has been analysed for comparison of LST difference across the border. The result shows that the I sraeli side does have significantly higher surface temperature in spite of its denser vegetation cover than the Egyptian side where bare sand is preva lent.