Coupling of the LM and ECHAMS/MESSy for consistently investigating chemistry and transport from the global to the regional scale
Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
Final Report Abstract
The numerical weather prediction model of the Consortium for Small Scale Modelling (COSMO), maintained by the German weather service (DWD), has been connected with the Modular Earth Submodel System (MESSy). MESSy provides the infrastructure and includes, among others, the process and diagnostic submodels for atmospheric chemistry simulations. Furthermore, MESSy is highly flexible allowing model setups with tailor made complexity, depending on the scientific question. The newly built regional atmospheric chemistry model COSMO/MESSy is as consistent as possible with the previously developed global atmospheric chemistry model ECHAM5/MESSy (EMAC). The regional model COSMO has been nested online into the atmospheric general circulation model ECHAM5 within the Modular Earth Submodel System (MESSy) framework. As ECHAM5 and COSMO have been equipped with the MESSy infrastructure, this implies that the same process formulations (MESSy submodels) are available for both models. This guarantees the highest degree of achievable consistency for both the meteorological and chemical conditions at the domain boundaries of the nested limited-area model, and between the process formulations on all scales. The online nesting of the different models is established by a client-server approach with the newly developed Multi-Model-Driver (MMD), an additional component of the MESSy infrastructure. With MMD an arbitrary number of model instances can be run concurrently within the same message passing interface (MPI) environment, the respective coarser model (either global or regional) is the server for the nested finer (regional) client model, i.e., it provides the data required to calculate the initial and boundary fields to the client model. Online nesting means that the coupled (client-server) models exchange their data via the computer memory, in contrast to the data exchange via files on disk in common offline nesting approaches. Thus, disk-space intensive and time consuming intermediate and pre-processing steps are entirely avoided and the time interpolation errors of common offline nesting approaches are minimised. MMD consists of a library, which is based on the MPI standard and two new MESSy submodels for the server and client models, respectively. For the interpolation of the coarse grid data provided by the server models to the grid of the respective client model (COSMO/MESSy) the offline pre-processing tool INT2LM provided by the DWD has been implemented as a submodel. The online coupled system is called MECO(n), which stands for “MESSy-fied ECHAM and COSMO models n-times nested”. The technical development of the online coupling has been very challenging. It was only possible to finish and document the technical development and to perform a detailed meteorological evaluation of the online-coupled system. The chemical aspects of the model are still under evaluation. In the near future, MECO(n) will be applied to simulate atmospheric chemistry exploring the model's full capabilities during meteorologically challenging conditions. The project led to the funding of a project within the BMBF activity MiKlip.
Publications
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Development cycle 2 of the Modular Earth Submodel System (MESSy2). Geosci. Model Dev., 3, 717–752, 2010; with supplement: MESSy TIMER User Manual
Jöckel, P., A. Kerkweg, A. Pozzer, R. Sander, H. Tost, H. Riede, A. Baumgaertner, S. Gromov and B. Kern
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Improving the time-splitting errors of one-dimensional advection schemes in multidimensional applications. Atmospheric Research, 97, 619-631, 2010
Bott, A.
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The 1-way on-line coupled model system MECO(n): Part I: COSMO/MESSy. Geosci. Model Dev. Discuss., 4, 1305-1358, 2011; with supplement: COSMO/MESSy Implementation Documentation
Kerkweg A., and P. Jöckel
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The 1-way on-line coupled model system MECO(n): Part II: On-line Coupling. Geosci. Model Dev. Discuss., 4, 1359-1402, 2011; with supplements: Multi-Model-Driver (MMD) Library Manual, and Multi-Model-Driver (MMD) User Manual
Kerkweg A. and P. Jöckel
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The 1-way on-line coupled model system MECO(n): Part III: Meteorological Evaluation. Geosci. Model Dev. Discuss., 4, 1533-1567, 2011
Hofmann, Ch., A. Kerkweg, H. Wernli, and P. Jöckel
