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RESEARCH PRODUCT

Understanding the Effects of Fires on Surface Evapotranspiration Patterns Using Satellite Remote Sensing in Combination with an Energy Balance Model

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Forest fires are highly destructive for nature, affecting the landscape, the natural cicle of the vegetation, and the structure and functioning of ecosystems. Beyond that, they also provoke changes in the local and regional meteorology, and particularly in the surface energy flux patterns. In a fire-affected area, changes in the ecosystem structure and species composition modify the evapotranspiration (LE) and the rest of the terms involved in the energy balance equation. Besides, these changes in the local energy balance may persist for decades (Randerson et al., 2006). There is an increasing concern among the scientific community about the effect of forest fires on climate change at this point (Randerson et al. 2006). In this work we focus on the study of the changes in the energy flux patterns after a forest fire, with particular emphasis on the evapotranspiration, which effect on the global system should be further analyzed by the radiative forcing models. The physical characterization of the hydrological processes plays a very important role in the framework of the activities for the management of hydrological resources. Particularly, the soil-vegetation-atmosphere energy exchanges are the basis of an appropriate hydrological balance, and thus, of an appropriate planning of the hydrological resources. The fusion of physical models for estimating the hydrological balance, and particularly the evapotranspiration, with technological advances for the characterization of hydrological, hydro-geological, and atmospheric issues, is of great utility. Although there are several surface-based methods that can accurately measure surface heat fluxes at point locations, it is not feasible to use a network of these systems to create spatially distributed flux maps because of the high variability of real landscapes. As stated by Scott et al. (2000), micrometeorological approaches can only realistically provide measurements representative of a particular type of vegetation cover when there is a reasonably extensive, uniform area of that vegetation immediately upwind of the instruments. The use of remote sensing techniques supplies the frequent lack of ground-measured variables and parameters required to apply the local models at a regional scale. Modelling evapotranspiration is very sensitive to the surface features and conditions. For this reason, a regional model must