Tests of WRF Microphysics in GFS

Abstract:

Zhao and Carr microphysics scheme has been implemented into the NCEP Global Forecasting System (GFS) for many years. It predicts total cloud condensate (cloud water or ice). The scheme has significantly improved the forecast skills compared with its previous diagnostic cloud scheme. However, it has become too simple in several aspects as the computing power and resolution increase. Many microphysical processes are simplified or neglected for computing efficiency. Precipitation is diagnosed and falls to the surface instantaneously. Studies have shown that more sophisticated microphysics schemes generally give better results compared with observations. We are testing several sophisticated microphysics schemes from the Weather Research and Forecasting Model (WRF) in the GFS. These schemes have more cloud species and more physically-based parameterized processes. We will adjust or modify the schemes for the GFS. Partial cloud and cloud overlapping will be added to these schemes. The comparison will be focus on the precipitation skills and cloud properties and their effects.