P22 Simulating the diurnal cycle of convective precipitation in North America's current and future climate with a convection-permitting model

Scaff, Lucia, Andreas Prein, Yanping Li, Changhai Liu, Kyoko Ikeda, and Roy Rasmussen, University of Saskatchewan

Convection-permitting models (CPMs) are able to improve the simulation of the convective diurnal cycle of precipitation compared to simulations that use deep convection parameterizations. They allow a more reliable assessment of atmospheric processes at smaller scales, such as the frequency, amount, timing and location of convective precipitation.
In this work we analyze the simulation of the summertime diurnal cycle of precipitation in a current and end of century North American scale WRF-CPM simulation . An extensive validation of the retrospective simulation was performed against rain gauge observations and a gridded radar product (stage IV) as well as an assessment of climate change impacts on diurnal cycle characteristics. The phase and the amplitude of the modeled diurnal cycle is well simulated by the current climate WRF-CPM. The propagation of convective systems in the central U.S. is well represented, but the model is not able to simulate early morning rainfall maxima in the eastern Plains. The main differences in a warmer climate are an increase of the precipitation amplitude in early summer caused by an increase the precipitation intensity and a decrease on the rainfall frequency.