Simulation of subgrid orographic precipitation with an embedded 2?￠????D cloud?￠????resolving model

摘要

By explicitly resolving cloud?￠????scale processes with embedded two?￠????dimensional (2?￠????D) cloud?￠????resolving models (CRMs), superparameterized global atmospheric models have successfully simulated various atmospheric events over a wide range of time scales. Up to now, however, such models have not included the effects of topography on the CRM grid scale. We have used both 3?￠????D and 2?￠????D CRMs to simulate the effects of topography with prescribed ?￠????large?￠????scale?￠???? winds. The 3?￠????D CRM is used as a benchmark. The results show that the mean precipitation can be simulated reasonably well by using a 2?￠????D representation of topography as long as the statistics of the topography such as the mean and standard deviation are closely represented. It is also shown that the use of a set of two perpendicular 2?￠????D grids can significantly reduce the error due to a 2?￠????D representation of topography.