Talk: High resolution climate modeling of the water cycle over the United States including potential climate change impacts

Department of Hydrology and Atmospheric Sciences

4 pm on Thursday, September 24, 2020
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Roy Rasmussen
National Center for Atmospheric Research (NCAR)

Abstract

The NCAR Water System program strives to improve the full representation of the water cycle in both regional and global models. Our previous high-resolution simulators using the Weather Research and Forecast (WRF) mesoscale model over the Rocky Mountains revealed that proper spatial and temporal prediction of snowfall adequate for water resource and climate change purposes can be achieved with the appropriate choice of model grid spacing (<6 km horizontal) and parameterizations. The climate sensitivity experiment consistent with expected climate change showed an altered hydrological cycle with increased fraction of rain versus snow, increased snowfall at high altitudes, earlier melting of snowpack, and decreased total runoff. Our recent work has expanded the domain to the Continental U.S. (CONUS) and increased the time period for historical and future climate to 13 years. A domain expansion provides the opportunity to assess changes in the water cycle across the entire USA without the use of a convective parameterization (so called convective permitting simulations). This talk will focus on the water cycle in the central U.S. and eight U.S. mountain ranges, including likely changes to the amount of snowpack and spring melt-off, critical to agriculture in the western U.S.

Bio

Dr. Roy Rasmussen is the senior scientist and director of the hydrometeorology applications program at the National Center for Atmospheric Research (NCAR). Dr. Rasmussen got his Ph.D. from UCLA in Atmospheric Sciences in 1982. He has studied water cycle, regional climate change and variability, nowcasting, microphysical parameterizations over 39 years. He is well known for pioneering the development and application of continental-scale, high-resolution, convection-permitting climate models. Due to his excellent achievement, Dr. Rasmussen achieved UCAR Outstanding Publicaiton Awards in 2000 and 2015 and was nominated by the UCAR Distinguished Achievement Award in 2019.