With the measurements of directional surface brightness temperature at three view angles, e.g. 0°, 23° and 52°, Tv and Ts are retrieved using Eq.(26) and Eq.(27). For the studied area, LAI was measured as 0.5 corresponding to fc 30%; 6V and es were 0.98 and 0.95 respectively.
Theoretically, Tv and Ts can be derived using measurements of brightness at any pair of view angles, such as TBo(0) and TBo(23), TBO(0) and TBo(52), and and However, in our study, due to the small field of view of the radiometer used, only bare soil was seen in the field of view when measurements were done at nadir, so that the TBO(0) is the soil brightness temperature. To obtain Ts from TB0 (0), es = 0.95 was used. This was taken as the reference to evaluate the Ts retrieved from TBO(23) and The same measurements of and give Agreement of between retrievals and measurements was good, with a root mean square difference (RMSD) of 0.8 K (Fig.4).
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