Strong control of surface roughness variations on the simulated dry season regional atmospheric response to contemporary deforestation in Rondonia, Brazil

摘要

abstract_textpThe atmospheric effects of Amazon deforestation have frequently been studied in the context of small scales (approximate to 1 km) and very large scales (hundreds of kilometers). However, analysis of intermediate-scale deforestation (tens of kilometers) has received less attention, despite the fact that it better represents the contemporary landscape in some parts of the Amazon. In this study, the dynamic and thermodynamic effects of contemporary intermediate-scale deforestation in Rondonia, Brazil are investigated through variable resolution Global Circulation Model (GCM) simulations carried out with the Ocean-Land-Atmosphere Model. In particular, the atmospheric response to surface roughness changes brought about by deforestation is emphasized. This study shows that reductions in surface roughness associated with intermediate-scale deforestation give rise to a mesoscale circulation. This circulation is capable of convective triggering, but it also weakens the turbulent exchange of energy between land and atmosphere. Furthermore, this mesoscale circulation has distinct impacts on the hydroclimates of the western and eastern halves of Rondnia, increasing shallow cloudiness in the former while suppressing it in the latter. These results show that the atmospheric response to contemporary intermediate-scale deforestation in Rondnia is likely to be more influenced by differences in surface roughness between forest and forest clearings than by the differences in the surface energy partitioning./p/abstract_text