Abstract ID: 210

Predicting changes in convection and precipitation patterns due to deforestation along the Porto Velho-Manaus road

The Amazon basin has experienced significant deforestation over the past several decades. Conversion of forest to pasture and cropland is likely to cause important changes to the region’s water, energy and carbon cycles. Whereas most large-scale deforestation scenarios have shown a decrease in evapotranspiration and consequently a decrease in precipitation over much of the Amazon, with potential impacts in remote areas, regional studies have shown shift in patterns of precipitation, mainly increasing over the deforested areas associated with enhancement of local circulations due to differential heating between deforested and forested areas. The scale at which the above effects become dominant remains uncertain. In this work we explored the impacts of ongoing deforestation and the future scenarios on the circulations at regional and local scale, using a fully-coupled dynamic biosphere-atmosphere model (BRAMS-ED2) to obtain detailed empirical and mechanistic insight into the impact of such land use changes. The atmospheric initial and boundary condition were based on the ECMWF analysis, and the ecosystem was initialized with previous ED2 simulation for the current ecosystem state and with anthropogenic land use change scenarios for 2050. The runs were conducted at scales between 60 km and 16km, focusing on the Porto Velho-Manaus road (BR-319) region, and similar runs were conducted for both the wet and the dry season. The dry season runs showed a strong impact of the deforestation on the precipitation, which tended to become more abundant over the deforested regions. This effect was noticed over the areas in which the deforestation band was not too wide and the development of these patterns was associated with the differential heating forcing. During the wet season, however, the pattern becomes much less clear even though the differential heating forcing is still present.

Session:  Feedbacks to Climate - Effects of deforestation on regional and global climate.

Presentation Type:  Oral