The representation of a synoptic-scale weather system in a thermodynamically adjusted version of the ECHAM4 general circulation model

摘要

In this work, a strong cyclone event is simulated by the general circulation model (GCM) ECHAM4 for studying the representation of weather systems in a climate model. The system developed along the East Coast of the U.S.A. between the 12th and 14th of March 1993. The GCM simulation was started from climatological conditions and was continuously forced to the analyzed state by a thermodynamical adjustment based on the Newtonian relaxation technique (nudging). Relaxation terms for vorticity, divergence, temperature, and the logarithm of surface pressure were added at each model level and time step. The necessary forcing files were calculated from the ECMWF re-analysis (ERA15). No nudging terms were added for the components of the water cycle.