Impact of Deforestation on Cloud Properties and Rainfall Over the Costa Rica-Nicaraguan region

The Nicaraguan-Costa Rican region in Central America exhibits the typical pattern of complex deforestation now seen throughout the tropics. The region is a mixture of lowland, mostly converted to agriculture, and mountainous regions, where pristine forests still persist. At present the northern fertile plains of Costa Rica are mostly utilized for agriculture. However in the adjacent regions of southern Nicaragua lowland forests are relatively intact. The extensive agricultural areas of northern Costa Rica is a region of discontinuity in the proposed Mesoamerican Biological Corridor which would connect the montane forests in Costa Rica to the lowland forests in Nicaragua. The present study is part of a larger study which investigates the effects of continuing lowland deforestation and associated regional climate change in Central America on the stability of the entire proposed Mesoamerican Biological Corridor. The present work focuses on the effects of land use on the formation of cloudiness, cloud properties and rainfall in the forested regions of southern Nicaragua and the deforested regions of northern Costa Rica. Land surface and cloud properties are retrieved using the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite data and products. The land surface properties retrieved are land surface temperature, albedo, Normalized Difference Vegetation Index (NDVI), Available Soil Moisture fraction and surface energy fluxes. The cloud properties retrieved are cloud optical thickness and effective radii. In addition, the frequency of cumulus cloudiness on hourly basis are derived from the Geostationary Operational Environmental Satellite (GOES) and rainfall is studied using Tropical Rainfall Measuring Mission (TRMM) satellite products. The correlations between the surface properties, cloud properties, cumulus cloudiness and rainfall as a function of ecosystem and topography is examined. Previous modeling work has shown that in this region the lowlands and highlands are highly coupled. Preliminary results from numerical modeling studies illustrating the impacts of deforestation on the regional climate will also be presented.