15A.5
A preliminary assessment of future changes in the severe thunderstorm environment in North America
Patrick T. Marsh, University of Oklahoma, Norman, OK; and D. J. Karoly and H. E. Brooks
Global climate models (GCMs) are becoming increasingly important in the simulation of climate changes associated with increases in greenhouse gas concentrations in the atmosphere. However, little, if anything has been said about the effects of increased anthropogenic forcing on severe convective weather. Recent improvements in global climate model 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 probability of occurrence 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 CAPE, deep layer shear, and their combination. The methodology used by Brooks et al. (2003) serves as the basis to examine changes in the severe thunderstorm environment in North America under global warming as simulated by the NCAR CCSM3 global climate model.
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 current severe thunderstorm environment qualitatively. This will be followed by a preliminary examination of the severe weather environment at the end of the 21st century simulated by the CCSM3 under the A2 SRES emission scenario. The focus will be on the changes in the distributions of CAPE, deep layer shear, and their combination. Projected changes in the probability of occurrence of severe thunderstorm environments in North America will be presented.
Recorded presentationSession 15A, Detection and attribution of climate change: Part IV
Thursday, 24 January 2008, 1:30 PM-3:00 PM, 215-216
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