The 1-way on-line coupled atmospheric chemistry model system MECO(n) – Part 3: Meteorological evaluation of the on-line coupled system

摘要

Three detailed meteorological case studies are conducted with the global andregional atmospheric chemistry model systemECHAM5/MESSy(→COSMO/MESSy)n, shortly named MECO(n).The aim of this article is to assess the general performance of the on-line coupling of the regional model COSMO to the global model ECHAM5.The cases are characterisedby intense weather systems in Central Europe: a cold front passagein March 2010, a convective frontal event in July 2007, and the high impactwinter storm "Kyrill" in January 2007. Simulations are performed with thenew on-line-coupled model system and compared to classical, off-line COSMOhindcast simulations driven by ECMWF analyses. Precipitation observationsfrom rain gauges and ECMWF analysis fields are used as reference, and bothqualitative and quantitative measures are used to characterise the quality ofthe various simulations. It is shown that, not surprisingly, simulations witha shorter lead time generally produce more accurate simulations. Irrespectiveof lead time, the accuracy of the on-line and off-line COSMO simulations arecomparable for the three cases. This result indicates that the new global andregional model system MECO(n) is able to simulate key mid-latitude weathersystems, including cyclones, fronts, and convective precipitation, asaccurately as present-day state-of-the-art regional weather prediction modelsin standard off-line configuration. Therefore, MECO(n) will be applied to simulate atmospheric chemistry exploring the model's fullcapabilities during meteorologically challenging conditions.