Climate change effects on precipitation organization : a summertime case study in the southeast United States

The delivery of precipitation through large and small scale precipitation features plays a key role in the hydrological cycle. Therefore, it is important to understand how the organization of precipitation will change as the earth warms. The organization of precipitation can be characterized into either widespread, mesoscale precipitation features (MPF) or short-lived, isolated precipitation features (IPF). The Weather Research and Forecasting (WRF) model was used to simulate precipitation features at a 3 km resolution during the 17-22 June 2010 period in the Southeast US under present and future climate conditions. In this methodology, the model is first run in present climate mode and then rerun with an adjusted initial state that adds projected temperature anomalies for the 2090s based on Representative Concentration Pathways (RCPs) 4.5 and 8.5 from the Coupled Model Intercomparison Project Phase 5 (CMIP5) in the IPCC Fifth Assessment Report (AR5). In the future climate simulations, small changes in precipitation occurred under RCP4.5 warming, but many significant changes were noted under RCP8.5 warming. Domain-averaged precipitation increased in the future climate simulations, with the largest changes over the ocean relative to the continent. In the future climates, IPF grew larger in length and eventually coalesced into MPF, reducing the total number of IPF and increasing the number of MPF. IPF and MPF also extended deeper into the troposphere and produced more precipitation overall