Dr. Matthew Van Den Broeke
Caruthers, A. L., 2017: Land Use Land Cover Change Effects on Southern Great Plains Precipitation. M.S. thesis, Dept. of Earth and Atmospheric Sciences, University of Nebraska-Lincoln, 96 pp.
Great Plains land use has changed substantially over the last 160 years, altering the properties of the land through increased settlement and advances in irrigation. Changing the interface between the land and atmosphere has implications for the atmospheric boundary layer, the regional circulation, the local surface energy budget and resulting precipitation patterns. Land use land cover (LULC) changes are an important topic for this region due to its heavy dependence on agriculture. This study investigates differences in Southern Great Plains precipitation patterns between four LULC scenarios: the pre-settlement, 1920’s, Dust Bowl and present day eras. Using the Weather Research and Forecasting (WRF) model coupled to the Community Land Model (CLM), simulations for each LULC scenario were run for a 13-year period (1990-2002), as this period encompasses a wide variety of remote forcing conditions. It is hypothesized that the impact of the conversion of native vegetation to cropland will alter the regional circulation of the Southern Great Plains through changes in the surface energy budget. Crops transpire more than native vegetation, such as grassland, which will result in higher surface latent heat fluxes, and higher surface dewpoints, in the modern day than in the earlier LULC scenarios. The increase in the surface latent heat flux will decrease the surface sensible heat flux, and 2m air temperatures will be cooler in the modern day, ultimately resulting in an altered regional circulation. It is hypothesized that the shift in the regional circulation will have an impact on the moisture flux and moisture transport from the Gulf of Mexico. The greater surface latent heat flux, along with the shift the regional circulation will result in greater precipitation in the modern day than in the pre-settlement, 1920’s and Dust Bowl scenarios.
Advisor: Matthew Van Den Broeke