The global forecast system's monsoon and its dependence on physical process parameters

The South Asian monsoon flow system is examined in analyses and forecasts by the Global Forecast System (GFS) model from NOAA, with a special focus on its tropical convection and humidity relationships. Experimental hindcast runs are compared, with modifications to aspects of the humidity-dependent entrainment in the deep convection scheme. Simplifications are found to be possible with almost no impact. Then, we seek to discern the effects of, and optimize, the reduced parameter set of the simplified scheme over a wide range of values. The goal is improved forecast skill in operational versions of the GFS.