Mechanisms for the seasonal transition of precipitation organization in the southeastern United States: Current and future climate Grant uri icon

abstract

  • Simulations of regional precipitation changes are among the least certain aspects of climate prediction. Yet as climate changes and population increases, water management and use policies in regions like the southeastern United States (SE US) will rely increasingly on improved climate forecasts of precipitation variability and organization. The impacts of precipitation on society and the mechanisms that control precipitation are in part determined by whether the rain is organized as short-lived isolated thunderstorms that cover part of a city or as widespread long-lasting rain systems that cover half a state. In turn, the strong dependence of the seasonal and diurnal cycle of precipitation on precipitation system organization illustrates a key link between the organization of rain and Earth's dominant large-scale forcing mechanisms, that is, seasonality and diurnal variation of solar radiation. This result suggests the possibility of bootstrapping regional climate prediction of precipitation, for which there is low skill, to highly predictable modes of climate variability such as the seasonal and diurnal radiation forcing or even the global increase in temperature due to greenhouse gas forcing. This project will combine present and future climate simulations with the Weather Research and Forecasting (WRF) model, with a precipitation organization classification algorithm and a radar-based precipitation organization dataset, to study the effects of climate change on regional precipitation organization. Future climate WRF simulations will utilize the pseudo-global warming approach. The overarching goal of this project is to study how precipitation organization in the SE US will be modified in a warmer world. Three questions will be addressed. First, can WRF capture the observed seasonal and diurnal cycles of precipitation organization? Second, what are the dominant large-scale mechanisms that control the seasonal and diurnal changes in precipitation organization? Third, and most importantly, how does climate change impact the seasonal and diurnal evolution of precipitation organization and extreme precipitation, as demonstrated by WRF pseudo-global warming simulations?

date/time interval

  • April 2020 - March 2022