An explicit cloud predicting scheme is developed for the Florida State University Global Spectral Model (FSU-GSM). Both cloud water and cloud cover are prognostic variables in the scheme, but they are not advected in the current version. Cloud liquid water and cloud ice are distinguished by a prescribed function of temperature. Source terms are considered for convective cloud as well as stratiform cloud. The predicted cloud water content and cloud cover are provided to the radiation scheme.
The model produces reasonable amounts of cloud cover and cloud water. Clouds originating from convection are important for cloud cover and cloud water except for the polar region. In the tropics, clouds originating from convection account for approximately half of the total cloud cover, and the majority of the high cloud coverage. They also produce half of the cloud water in the mid-latitudes, and are an essential source of the cloud water in the tropics.
The outgoing longwave radiation in the tropics is improved by the explicit scheme, because the scheme includes the clouds originating from the convection. High clouds from convection are essential in the tropics, and have a large influence on the outgoing longwave radiation.