The 1-way on-line coupled atmospheric chemistry model system MECO(n) – Part 1: Description of the limited-area atmospheric chemistry model COSMO/MESSy

摘要

The numerical weather prediction model of the Consortium for SmallScale Modelling (COSMO), maintained by the German weather service(DWD), is connected with the Modular Earth Submodel System(MESSy). This effort is undertaken in preparation of a new,limited-area atmospheric chemistry model. Limited-area models requirelateral boundary conditions for all prognostic variables.Therefore the quality of a regional chemistry model is expected toimprove, if boundary conditions for the chemical constituents areprovided by the driving model in consistence with the meteorologicalboundary conditions. The new developed model is as consistentas possible, with respect to atmospheric chemistry and relatedprocesses, with a previously developed global atmospheric chemistrygeneral circulation model: the ECHAM/MESSy Atmospheric Chemistry(EMAC) model. The combined system constitutes a new research tool,bridging the global to the meso-γ scale for atmosphericchemistry research. MESSy provides the infrastructure and includes,among others, the process and diagnostic submodels for atmosphericchemistry simulations. Furthermore, MESSy is highly flexible allowingmodel setups with tailor made complexity, depending on the scientificquestion. Here, the connection of the MESSy infrastructure to theCOSMO model is documented and also the code changes required forthe generalisation of regular MESSy submodels. Moreover,previously published prototype submodelsfor simplified tracer studies are generalised to be plugged-in andused in the global and the limited-area model. They are used toevaluate the TRACER interface implementation in the new COSMO/MESSymodel system and the tracer transport characteristics,an important prerequisite for future atmosphericchemistry applications. A supplementary document with further detailson the technical implementation of the MESSy interface into COSMO witha complete list of modifications to the COSMO code is provided.