Sensitivity of the MM5 mesoscale model to physical parameterizations for regional climate studies: Annual cycle

Abstract

We present an analysis of the sensitivity of a high-resolution integration of the MM5 mesoscale model over the Iberian Peninsula to different physical parameterizations. Several (16) five-year runs of the MM5 model with varying parameterizations have been carried out and the results have been extensively compared with observational precipitation and surface temperature data. Less systematic tests were conducted to compare the parameterization uncertainty with that induced by the boundary conditions and the observational uncertainty. No parameterization combination was found to perform best for simulating both precipitation and surface temperature in every season and subregion of the Iberian Peninsula. The Kain–Fritsch cumulus scheme was found to simulate unrealistically high summer precipitation, while the radiation parameterizations tested were found to have little impact on our target variables. Other factors, such as the choice of boundary conditions were found to have an impact on the results as large as the selection of parameterizations. The uncertainty in the MM5 ensemble is of the same order of magnitude as the observational uncertainty, except in summer.