The iterative flux-profile method for remote sensing applications

Iterative flux-profile methods allow calculation of sensible heat and momentum fluxes using temperature gradients and wind speed data obtained in the lower atmosphere. Flux-profile methods are also applied to the problem of regional evapotranspiration evaluation by the use of satellite imagery. The large number of pixels in these images and the long image time series that have become available make it necessary to develop reliable, fast and accurate algorithms to process the data. In this paper an analysis is made of the equations underlying the flux-profile method with the practical objective to improve the existing procedures for application with large datasets. After a review of the iterative methods to arrive at the solution, simple changes are suggested to improve estimates of the initial value and to speed up function evaluation. As an illustration of the suggested changes, a NOAA Advanced Very High Resolution Radiometer (AVHRR) case study from western Turkey is discussed. It is shown that the improved iterative algorithm is in this case a factor of 4-5 faster than the standard method. The results are also compared with those obtained by a recent analytical approximation.