Regional, extreme daily precipitation in NARCCAP simulations

Abstract

Extreme precipitation is a key topic in climate research. As the environment continues its steady increase in temperatures through increased greenhouse-gas emissions, conditions become more favorable for storm development that produce extreme events. This can have devastating effects in the upper Mississippi region, where agriculture dominates the regional economy. To understand trends in extreme precipitation events of future climates, using climate models becomes essential. Because extreme precipitation events predominantly occur through relatively small-scale dynamics, the coarser resolution of global climate models (GCMs) is unable to capture fully such events. Therefore, regional climate models (RCMs) with higher resolution are used to simulate and investigate these events. In order to gain confidence in the models’ ability to simulate future extreme events, we compare model simulations of contemporary climate with observations to determine if simulated extremes are occurring in conditions similar to the observed. The overall objective of this work is to evaluate model performances from contemporary simulations by RCMs participating in the North American Regional Climate Change Assessment Program (NARCCAP). For comparison, we also examine output from a time-slice GCM of comparable resolution and a coarser atmosphere-ocean GCM. This work focuses on the upper Mississippi region for the winter season (December-JanuaryFebruary), when it is assumed that resolved synoptic circulation governs precipitation, comparing 18 years of simulations with observations.