Cooperative Institute for Research in Environmental Sciences

Evaluation of polar MM5 simulations of Greenland's atmospheric circulation

A complete annual cycle over the Greenland ice sheet is simulated with the Polar MM5, a mesoscale model optimized for use over extensive ice sheets. These simulations are compiled from a series of short duration (48 hour), forecast mode, simulations. The model output is compared to observations primarily from the Greenland Climate Network automatic weather station (AWS) array. The model simulations show a high degree of skill for all variables evaluated with the AWS data (pressure, temperature, water vapor mixing ratio, wind speed and direction, downwelling shortwave radiation, and net radiation) for all seasons, although the use of a fixed albedo in the Polar MM5 leads to large errors in the simulated net radiation budget over melting ice surfaces during the summer months. The modeled precipitation distribution agrees with available observations in the interior of the ice sheet but is excessive along the steep margins of the island. A discussion of possible future applications of the Polar MM5 is presented.