Exploring the Cloud and Radiation Interactions in the GFS

Abstract:

Clouds and precipitation are important in regulating the radiative fluxes, radiative heating distribution and temperature profile. Yet, there are many uncertainties in predicting the clouds and precipitation in the state-of-the-art global weather and climate forecast systems. The interactions between the cloud and radiation are often crudely parameterized. In this study attempts are made to examine the sensitivities of radiative flux calculation to the cloud and precipitation properties in the GFS. Different physically based cloud and precipitation properties and their representations will be explored and tested in the GFS. The optimal representation of the cloud and precipitation will be used to reduce the existing temperature bias in the GFS.