“…Land surface variables, such as surface temperature, surface hemispherical albedo, Normalized Difference Vegetation Index (NDVI) and surface thermal emissivity can be derived directly from satellite observations (e.g., Susskind et al, 1984;Che'din et al, 1985;Tucker, 1986;Wan and Dozier, 1989;Menenti et al, 1989;Li, 1990, 1995;Watson et al, 1990;Baret and Guyot, 1997;Price, 1992;Kahle and Alley, 1992;Li and Becker, 1993;Qi et al, 1994;Schmugge et al, 1995;Sobrino and Raissouni, 2000;Li et al, 2000Li et al, , 2003Jia et al, 2003b;Menenti et al, 2001). The regional heat flux can be obtained indirectly using the derived parameters and variables (Pinker, 1990).…”