An assessment of measures of storminess: Simulated changes in northern hemisphere winter due to increasing CO2

Two methods for identifying mid-latitude synoptic time scale variability have been applied to data from the first United Kingdom Meteorological Office (UKMO) coupled ocean-atmosphere model experiments with present day and gradually increasing CO2 concentrations. In the first the standard deviation of the time filtered mean sea level pressure field is taken to identify the location of the storm track and in the second individual cyclones are identified using synoptic criteria. The results have been compared with data from a 10 year archive of UKMO analysis. In the enhanced CO2 experiment the changes in storminess identified by the two methods have been compared with changes in mean and maximum winds with special emphasis on the North Atlantic. The relative utility of the different measures for predicting potentially damaging synoptic events is discussed.