Date of Award

8-27-2010

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical Engineering

Abstract

The work presented in this document is an investigation of the climate impacts of land cover and land use (LCLU) changes in coastal tropical regions under conditions of global climate change (global warming, GW) using the Regional Atmospheric Modeling System (RAMS) as the main research tool, and taking the northeastern region of the Caribbean island of Puerto Rico as the test case. To achieve this goal an ensemble of climate simulations were performed, combining two LCLU and two GW scenarios. Reconstructed agricultural maps combined with reconstructed sea surface temperatures (SST) form the Past (1951-1956) climate scenario, while the Present (2000-2004) scenario was supported with high-resolution remote sensing data. The climate reconstruction approach is validated with observational data from surface weather stations for both timeframes. Results indicate that LCLU changes produced the largest air temperature differences over heavily urbanized regions and that these changes occur near the surface. The influence of the global warming signal is to induce a positive inland gradient for maximum temperature, possibly due to increased trade winds in the present climatology. In terms of minimum temperatures, the global warming signal induces temperature increases along the coastal plains and inland lowlands. The global warming signal also produced stronger trade winds with an easterly-southeasterly direction. These changes cause a shift in the location of a convergence zone north of the Central Mountains, where without orographic lifting clouds have higher bases and the total column liquid water content is decreased above higher elevations. This combination of factors translates into a dramatic decrease in surface accumulated precipitation in the highlands of the region of interest due to global climate change. Regarding the combined effects of LCLU changes and global warming, results indicate that the impact of LCLU changes on temperatures, total column liquid water content, and surface accumulated precipitation are relatively independent of the large-scale climate conditions, and vice versa.

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