Abstract
This study highlights the possibilities and constraints of determining instantaneous spatial surface radiation and land heat fluxes from satellite images in a heterogeneous urban area and its agricultural and natural surroundings. Net radiation was determined using ASTER satellite data and MODTRAN radiative transfer calculations. The soil heat flux was estimated with two empirical methods using radiative terms and vegetation indices. The turbulent heat fluxes finally were determined with the LUMPS (Local-Scale Urban Meteorological Parameterization Scheme) and the ARM (Aerodynamic Resistance Method) method. Results were compared to in situ measured ground data. The performance of the atmospheric correction was found to be crucial for the estimation of the radiation balance and thereafter the heat fluxes. The soil heat flux could be modeled satisfactorily by both of the applied approaches. The LUMPS method, for the turbulent fluxes, appeals by its simplicity. However, a correct spatial estimation of associated parameters could not always be achieved. The ARM method showed the better spatial results for the turbulent heat fluxes. In comparison with the in situ measurements however, the LUMPS approach rendered the better results than the ARM method.
Highlights
The surface energy budget is an important term in the climatological system
To convert the spectral reflectances ρ of ASTER obtained from the atmospheric correction algorithm to broadband albedos, an empirical equation was used, which was gained from a multiple regression approach similar to [32]
The comparison is executed by the analysis of mean absolute differences (MAD), which are the mean values of the absolute differences between associated values from each of the in situ measurements and the remote sensing approaches
Summary
The surface energy budget is an important term in the climatological system It determines how the energy received from solar irradiation is distributed to other climatological terms. Areas with a high albedo reflect back a high amount of the solar irradiation, following that, the available energy for heating the soil and the near-surface air layers or evaporating water from the surface is low. A change of the surface albedo has a direct impact on the radiative forcing and on the microclimate. Such changes can arise by natural processes or through human impact. More than half of the world’s population lives in urban regions and megacities are a consequence of this migration process
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