A preliminary investigation of severe thunderstorm environment distributions under global warming as simulated by CCSM3

Global climate models (GCMs) are becoming increasingly important in the prediction of climate changes associated with an increase in anthropogenic forcing. However, little has been said about the effects of increased anthropogenic forcing on severe convective weather. Recent improvements in Community Climate Systems Model (CCSM) resolution and increased data storage capabilities have allowed for climate simulations of resolutions similar to those of the NCAR / NCEP global reanalysis to be archived at six hour intervals.

Brooks et al. (2003) demonstrated that threat of significant severe convective weather increases with increasing Convective Available Potential Energy (CAPE) and 0 to 6 kilometer deep layer shear. Additionally, Brooks et al.(2003) went on to demonstrate that the NCAR / NCEP global reanalysis data can be used as a surrogate for observational fields of several important convective parameters , including, but not limited to, CAPE, deep layer shear, and their combination. The methodology used by Brooks et al. (2003) will serve as the basis to examine changes in the severe weather environment under global warming as simulated by the CCSM3.

A brief comparison of the current CCSM3 severe thunderstorm environment to that of the global reanalysis data will be presented to illustrate the ability of the CCSM3 to simulate the severe thunderstorm environment qualitatively. This will be followed by a preliminary examination of the severe weather environment under the A2 SRES emission scenario. This examination of the simulated future climate will focus on the qualitative changes in the distributions of convective parameters – particularly CAPE, deep layer shear, and their combination.