The Role of Convective Gustiness in Reducing Seasonal Precipitation Biases in the Tropical West Pacific

作     者：Harrop, Bryce E. Ma, Po-Lun Rasch, Philip J. Neale, Richard B. Hannay, Cecile 

作者机构：Pacific Northwest Natl Lab Atmospher Sci & Global Change Div Richland WA 99354 USA Natl Ctr Atmospher Res POB 3000 Boulder CO 80307 USA 

出 版 物：《JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS》 (J. Adv. Model. Earth Syst.)

年 卷 期：2018年第10卷第4期

页      面：961-970页

核心收录：

基　　金：NOAA Climate Observations and Monitoring (COM) program Energy Exascale Earth System Model (E3SM) project U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research Office of Science of the U.S. Department of Energy [DE-AC02-05CH11231] Department of Energy [DE-AC05-76RL01830] 

主　　题：tropical precipitation model parameterization gross moist stability 

摘      要：Precipitation is an important climate quantity that is critically relevant to society. In spite of intense efforts, significant precipitation biases remain in most climate models. One pervasive and persistent bias found in many general circulation models occurs in the Tropical West Pacific where northern hemisphere summer-time precipitation is often underestimated compared to observations. Using the DOE-E3SM model, the inclusion of a missing process, convective gustiness, is shown to reduce those biases through a net increase in surface evaporation. Gustiness in surface wind fields is assumed to arise empirically in proportion to the intensity of convective precipitation. The increased evaporation can be treated as an increase in the moist static energy forcing into the atmosphere. A Normalized Gross Moist Stability (NGMS) framework (which characterizes the relationship between convective forcing and convective response) is used to explore the processes responsible for the precipitation bias, and the impact of the gustiness parameterization in reducing that bias. Because the NGMS of the Tropical West Pacific is less than unity in the E3SMv1 model, the increase in energy forcing amplifies the increase in precipitation to exceed that of the evaporative flux. Convective gustiness favors increased precipitation in regions where the resolved surface winds are weak and convection is present.