Date of Award

12-2012

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Civil Engineering

Major Professor

Joshua S. Fu

Committee Members

Wayne T. Davis, John B. Drake, Yilu Liu

Abstract

In this study, the perennial problem of scale is addressed with an updated set of modeling tools that include global climate, atmospheric chemistry simulation, mesoscale weather, and air quality simulations. The evaluation of coupled model performance across geographic scales and the assessment of local scale climate change impacts under a fossil fuel intensive climate change scenario Representative Concentration Pathway (RCP 8.5) was achieved by linking the global climate model Community Earth System Model (CESM), with the regional climate model Weather Research and Forecasting (WRF) Model. This study is the first evaluation of dynamical downscaling using WRF on a 4km by 4km high resolution scale in the eastern US driven by the CESM. First, the global and regional climate model results were evaluated, and an inconsistency in skin temperature during the downscaling process was corrected by modifying the land/sea mask. In comparison with observations, WRF shows statistically significant improvement over CESM in reproducing extreme weather events, with improvement for heat wave frequency estimation as high as 98%. The RCP 8.5 was used to study a possible future mid-century climate extreme in 2057-2059. Both heat waves and extreme precipitation in 2057-2059 are more severe than present climate in the Eastern US. The Northeastern US shows large increases in both heat wave intensity (3.05 ºC higher) and annual extreme precipitation (107.3 mm more per year). The implementation of a global atmospheric chemistry model (CAM-Chem) in the Community Atmosphere Model (CAM) enables the connection between the global chemistry model (CAM-Chem) and the regional chemistry model Community Multi-scale Air Quality modeling system (CMAQ). The statistical evaluation demonstrates confidence in the regional chemistry downscaling methodology. In U.S., the mean concentrations of Maximum Daily 8-hr ozone is 3.1 to 9.5 ppbv higher during the heat wave periods than non-heat wave periods in RCP 8.5, stressing the importance of control strategies during the heat wave periods.

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