"The Arakawa-Schubert (Arakawa and Schubert, 1974; hereafter referred to as AS) type mass-ux based cumulus parameterization schemes are now used in many global forecast models and General Circulation Models (GCMs). One of the basic assumptions of the AS scheme is that the updraft occurs in a very small area of the grid box. This then led to the famous subsidence warming feature of the mass-ux schemes. The updraft condensation heating is exactly matched by the adiabatic cooling so the updraft stays in a moist- adiabatic prole. It is the compensating subsidence that does the warming and drying of the grid box. At NCEP, the Simplied Arakawa-Schubert (SAS) scheme (Pan and Wu, 1995) has been used in the Global Forecast System (GFS) model since 1994"--Introduction. [doi:10.7289/V5Z899CM (http://dx.doi.org/10.7289/V5Z899CM)]

National Weather Service (NWS)

United States