Land Use Land Cover Change Effects on Southern Great Plains Precipitation Patterns

Increased settlement and advances in irrigation have changed the land use land cover (LULC) of the Southern Great Plains over the last 160 years. This has changed the way the land and the atmosphere interact through alterations in the regional climate circulation, surface energy budget and subsequent precipitation patterns. This study investigates differences in Southern Great Plains precipitation patterns between four LULC scenarios: pre-settlement, 1920’s, Dust Bowl and present day eras by examining the regional climate circulation. Using the Weather Research and Forecasting (WRF) model coupled to the Community Land Model (CLM), simulations for each LULC scenario were run for a 12-year period (1990-2002), as this period encompasses a variety of remote forcing conditions. The analysis focuses on May-August. The positive soil moisture - precipitation feedback suggests that the evolution of soil moisture among the four scenarios is crucial to the LULC change effects on Southern Great Plains precipitation. The analysis reveals an increase in mean sea level pressure over much of the eastern Southern Great Plains with respect to the present day era, coinciding with a transition from native grassland to cropland with modern irrigation techniques. This altered the surface flow, resulting in areas of enhanced convergence and greater precipitation in the present day.