Abstract
Abstract This study aims at assess the importance of a conceptual representation of hydrological processes when modelling atmospheric circulation. It compares results from a regional atmospheric model that interprets land surface hydrological processes based on parameterizations with results from a two-way coupled atmosphere-hydrological model that has a process-based approach to the land surface hydrological cycle. These numerical models were applied to a region covering the Rio Grande basin, Brazil. The same input data, initial and boundary conditions were used on a 31-day simulation period. Results obtained from these simulations were compared to visible satellite images and gauging rainfall stations for three case studies that included a cold front, deep convective clouds and stable atmospheric conditions. Both models could reproduce regional patterns of air circulation and rainfall influenced by the orography of the basin. However, atmospheric processes driven by spatial gradients of land surface temperature or local surface heating were spatially better represented by the atmospheric-hydrological modelling system rather than the regional atmospheric model. Since areas characterized by spatial gradients of land surface temperature and local surface heating were closely associated with convergent air flows near land surface and strong vertical motion in the mid troposphere, this finding enhanced the role of a good representation of land surface hydrological processes for a better modelling the atmospheric dynamics.
Highlights
Este estudo tem como objetivo avaliar a importância de uma representação conceitual dos processos hidrológicos na modelagem da circulação atmosférica
Hydrological models are able to physically represent most of the water balance by integrating soil and surface water processes, they do not have any atmospheric module to deal with exchange of water between surface and atmosphere; estimates of runoff depend on how dense the rainfall gauge network is (St-Hilaire et al, 2003) or on the resolution of the atmospheric model used to estimate or forecast precipitation
This study outlines the role of a better representation of land surface hydrological processes in regional atmospheric models
Summary
Este estudo tem como objetivo avaliar a importância de uma representação conceitual dos processos hidrológicos na modelagem da circulação atmosférica. For a better understanding of these processes and how they are interrelated, many alternatives and strategies have been developed to estimate water fluxes between soil, surface and atmosphere at different spatial and temporal scales (Liang et al, 1994; Schaake et al, 1996; Wilson et al, 2001; Pitman, 2003; Balsamo et al, 2009). In this context, numerical models are widely recommended as tools capable of quantifying, predicting and assessing the soil, surface and atmospheric water budgets (Arnold et al, 1993; Maxwell and Miller, 2005; Bittelli et al, 2010). Comparisons between this integrated modelling system and a regional atmospheric model have been made in order to evaluate the influence of a process-based representation of land surface hydrological processes on regional atmospheric models
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