Abstract : E.1
Impact of a simple 'elevated heat source' parameterization on orographically triggered convection in the ECMWF model

Andrew Orr

It is widely recognised that convection can be triggered by orography.

However, in a forecast model it is difficult to determine and capture accurately the many meteorlogical processes which determine this, and to account for various subgrid-scale factors. Consequently, the resulting precipitation is often underestimated. To partially address this a simple 'elevated heat source' addition to the triggering function of the ECMWF model convective parameterization routines has been developed. Forecasts are compared with precipitation observations over the Rockies and the Alps. It is found that orographic precipitation is enhanced, sometimes significantly. Other feedbacks are also noticed.