Preliminary investigation into the severe thunderstorm environment of Europe simulated by the Community Climate System Model 3

Seasonal cycles of parameters conducive for the development of severe thunderstorms were computed using 20 years of output from the Community Climate System Model v3 (CCSM3) for both a 20th century simulation and a 21st century simulation. These parameters were compared against parameters calculated from the NCEP/NCAR Global Reanalysis data, which are of similar resolution. The CCSM3ʹs current simulation produced seasonal and spatial distributions of both mean CAPE and favorable severe environments that were qualitatively similar to the NCEP/NCAR Global Reanalysis, although the CCSM3 underestimates the frequency of severe thunderstorm environments. Preliminary comparisons of the CCSM3ʹs 21st century simulation under the IPCCʹs A2 emissions scenario to the 20th century simulation indicated a slight increase in mean CAPE in the cool season and a slight decrease in the warm season and little change in mean wind shear. However, there was a small increase in favorable severe environments for most locations resulting from an increase in the joint occurrence of high CAPE and high deep layer shear. Regions near the Mediterranean Sea experienced the biggest increase in both mean CAPE and favorable severe environments, regions near the Faeroe Islands experienced an increase in only seasonal mean CAPE, and regions across northern Europe experienced little change.