6533b85dfe1ef96bd12bddd3

RESEARCH PRODUCT

On the atmospheric dependence of the split-window equation for land surface temperature

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Abstract A split-window equation is derived for land surface temperature, yielding T = T4 + A(T4 − T5) + B(e), where T is the true surface temperature, T4 and T5 are the brightness temperatures measured in AVHRR channels 4 and 5, A is a coefficient related to the atmospheric transmittances in AVHRR channels 4 and 5, being dependent on the atmosphere type and independent on surface emissivity, and B(e) takes into account the emissivity effect, which depends on both the channel surface emissivities (e4 and e5) and the atmosphere type. The atmospheric dependence of split-window coefficients, A and B(e), is discussed by means of satellite measurements simulations and in situ data. It is shown that linear, global-scale algorithms can produce inaccurate estimates of surface temperature when they are applied to areas of reduced atmospheric variability. A simple, non-linear split-window algorithm has been proposed, in which A = a0+ a1(T4− T5). The constants a0and a1 have been calculated from a set of in situ and ...