Air flow and stability indices in GCM future and control runs

Indices have been used as indicators of synoptic-scale flow strength, shear vorticity, flow direction and static stability over Ireland and Britain. Changes in large-scale dynamic flow and static stability over the European region are expected because of shifting climate patterns, and investigation of how these indices change in future runs of global climate models allows us to estimate how this will affect storm frequency and intensity in the region. Analysis of frequency distributions shows an increase in westerly flows and decreases in most other flow directions, indicating an increase in rainfall for the region. The flow strength on days with strong winds increases in the future runs, as does the number of gale days. The future runs show not only an overall increase in atmospheric stability but also significantly larger areas with stronger instability during periods of extreme instability.