UK-HiGEM: Extratropical Cyclones and Storm Tracks in a High Resolution Coupled Climate Model

Midlatitude weather systems have huge socioeconomic impacts due to their strong winds and heavy rain. In order to correctly predict the future impact of these events it is essential that climate models can sufficiently represent the present climatological intensity and spatial pattern of storm tracks. HiGEM is a new high resolution coupled climate model based on the Met Office Hadley Centre's HadGEM1. It has a horizontal resolution of 0.83° latitude × 1.25° longitude in the atmosphere and 1/3° × 1/3° in the ocean. Using an objective feature tracking method, a comparison is made between HiGEM, the lower resolution model, HadGEM and ECMWF reanalysis data. Both HiGEM and HadGEM represent well the observed spatial distribution of the storm tracks. However, HiGEM shows higher track density than HadGEM, particularly in the Pacific. Distributions of maximum storm intensity and storm composites show that the higher resolution model produces stronger storms with lifecycles and 3D structures that compare more favourably to those found in the reanalysis.