Microphysical Sensitivity of Superparameterized Precipitation Extremes in the Contiguous United States Due to Feedbacks on Large‐Scale Circulation

Earth and Space Science

Mark D. Risser¹  Hossein Parishani²  Travis A. O'Brien³  Alexander B. Charn⁴  William D. Collins⁴ 

[1] Climate and Ecosystem Sciences Division Lawrence Berkeley National Laboratory Berkeley CA USA;Department of Earth System Science University of California Irvine CA USA;Department of Earth and Atmospheric Sciences Indiana University Bloomington IN USA;Department of Earth and Planetary Science University of California Berkeley CA USA;

关键词: extreme precipitation;    superparameterization;    microphysics;    Community Atmosphere Model;    ILIAD;    Climate Prediction Center Hourly Precipitation Dataset;   

DOI  :  10.1029/2019EA000731

来源: DOAJ

【 摘 要 】

Abstract Superparameterized (SP) global climate models have been shown to better simulate various features of precipitation relative to conventional models, including its diurnal cycle as well as its extremes. While various studies have focused on the effect of differing microphysics parameterizations on precipitation within limited‐area cloud‐resolving models, we examine here the effect on contiguous U.S. (CONUS) extremes in a global SP model. We vary the number of predicted moments for hydrometeor distributions, the character of the rimed ice species, and the representation of raindrop self‐collection and breakup. Using a likelihood ratio test and accounting for the effects of multiple hypothesis testing, we find that there are some regional differences, particularly during spring and summer in the Southwest and the Midwest, in both the current climate and a warmer climate with uniformly increased sea surface temperatures. These differences are most statistically significant and widespread when the number of moments is changed. To determine whether these results are due to (fast) local effects of the different microphysics or the (slower) ensuing feedback on the large‐scale atmospheric circulation, we run a series of short, 5‐day simulations initialized from reanalysis data. We find that the differences largely disappear in these runs and therefore infer that the different parameterizations impact precipitation extremes indirectly via the large‐scale circulation. Finally, we compare the present‐day results with hourly rain gauge data and find that SP underestimates extremes relative to observations regardless of which microphysics scheme is used given a fixed model configuration and resolution.

【 授权许可】

Unknown