Abstract

Abstract. The numerical weather prediction model of the Consortium for Small Scale 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 require lateral boundary conditions for all prognostic variables. Therefore the quality of a regional chemistry model is expected to improve, if boundary conditions for the chemical constituents are provided by the driving model in consistence with the meteorological boundary conditions. The new developed model is as consistent as possible, with respect to atmospheric chemistry and related processes, with a previously developed global atmospheric chemistry general 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 atmospheric chemistry research. 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. Here, the connection of the MESSy infrastructure to the COSMO model is documented and also the code changes required for the generalisation of regular MESSy submodels. Moreover, previously published prototype submodels for simplified tracer studies are generalised to be plugged-in and used in the global and the limited-area model. They are used to evaluate the TRACER interface implementation in the new COSMO/MESSy model system and the tracer transport characteristics, an important prerequisite for future atmospheric chemistry applications. A supplementary document with further details on the technical implementation of the MESSy interface into COSMO with a complete list of modifications to the COSMO code is provided.

Highlights

  • Since atmospheric chemistry related processes are often governed by local features, e.g. emissions of a power plant or fire emissions, which are not sufficiently resolved in global models, smaller scale models for atmospheric chemistry are required

  • The second part (Kerkweg and Jockel, 2012) is about a different issue, requires the Consortium for Small Scale Modelling (COSMO)/Modular Earth Submodel System (MESSy) model of the first part: there, we present a newly developed coupling technique that provides the boundary data required by the regional model directly from ECHAM5/MESSy via the newly developed Multi-Model-Driver (MMD) library and two corresponding submodels

  • The model system COSMO/MESSy consists of two model components: the numerical weather prediction model of the Consortium for Small Scale Modelling (COSMO model, Doms and Schattler, 1999) and the Modular Earth Submodel System (MESSy, Jockel et al, 2005)

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Summary

Introduction

Since atmospheric chemistry related processes are often governed by local features, e.g. emissions of a power plant or fire emissions, which are not sufficiently resolved in global models, smaller scale models for atmospheric chemistry are required. The second part (Kerkweg and Jockel, 2012) is about a different issue, requires the COSMO/MESSy model of the first part: there, we present a newly developed coupling technique that provides the boundary data required by the regional model directly (on-line) from ECHAM5/MESSy via the newly developed Multi-Model-Driver (MMD) library and two corresponding submodels. This on-line coupled system is called MECO(n), i.e. MESSy-fied ECHAM and COSMO models nested n times. 3 convective tracer transport (CVTRANS), simplified prognostic tracers (PTRAC), point sources and simplified chemistry (TREXP) and tracers of opportunity (DRADON)

Model description
The COSMO model
A big outer loop over the second horizontal dimension
The horizontal domain decomposition for parallel processing
TIMER: the “heart-beat” and event management
DATA: the data transfer interface
MPI: a high-level interface to the MPI library
TRANSFORM: the interface for grid transformations
TRACER: the management of constituents
Implementation of the MESSy submodels
Tracer transport
Submodel description
DRADON
CVTRANS
Tracer transport tests
Tests with artificial passive tracers
Summary and outlook
Infrastructure
Regular submodels
Full Text
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