The on-line coupled atmospheric chemistry model system MECO(n) – Part 5: Expanding the Multi-Model-Driver (MMD v2.0) for 2-way data exchange including data interpolation via GRID (v1.0)

Abstract

Abstract. As part of the Modular Earth Submodel System (MESSy), the Multi-Model-Driver (MMD v1.0) was developed to couple online the regional Consortium for Smallscale Modeling (COSMO) model into a driving model, which can be either the regional COSMO model or the global European Centre Hamburg general circulation model (ECHAM) (see Part 2 of the model documentation). The coupled system is called MECO(n), i.e., MESSy-fied ECHAM and COSMO models nested n times. In this article, which is part of the model documentation of the MECO(n) system, the second generation of MMD is introduced. MMD comprises the message-passing infrastructure required for the parallel execution (multiple programme multiple data, MPMD) of different models and the communication of the individual model instances, i.e. between the driving and the driven models. Initially, the MMD library was developed for a one-way coupling between the global chemistry-climate ECHAM/MESSy atmospheric chemistry (EMAC) model and an arbitrary number of (optionally cascaded) instances of the regional chemistry-climate model COSMO/MESSy. Thus, MMD (v1.0) provided only functions for unidirectional data transfer, i.e. from the larger-scale to the smallerscale models.Soon, extended applications requiring data transfer from the small-scale model back to the larger-scale model became of interest. For instance, the original fields of the larger-scale model can directly be compared to the upscaled small-scale fields to analyse the improvements gained through the smallscale calculations, after the results are upscaled. Moreover, the fields originating from the two different models might be fed into the same diagnostic tool, e.g. the online calculation of the radiative forcing calculated consistently with the same radiation scheme. Last but not least, enabling the two-way data transfer between two models is the first important step on the way to a fully dynamical and chemical two-way coupling of the various model instances.In MMD (v1.0), interpolation between the base model grids is performed via the COSMO preprocessing tool INT2LM, which was implemented into the MMD submodel for online interpolation, specifically for mapping onto the rotated COSMO grid. A more flexible algorithm is required for the backward mapping. Thus, MMD (v2.0) uses the new MESSy submodel GRID for the generalised definition of arbitrary grids and for the transformation of data between them.In this article, we explain the basics of the MMD expansion and the newly developed generic MESSy submodel GRID (v1.0) and show some examples of the abovementioned applications.

Are contributions of emissions to ozone a matter of scale? – a study using MECO(n) (MESSy v2.50)

“…These deviations from the measurements are in the range of comparable model systems (e.g. Knote et al, 2011;Stock et al, 2014). As already noted by Mertens et al (2016), CM50 exhibits a larger positive ozone bias than EMAC.…”

“…The transformation from the original resolution of the emissions onto the model grid is performed online (i.e. during runtime) via the MESSy submodel GRID (Kerkweg et al, 2018). Here, a conservative remapping approach is used to transform the emissions onto the model grid.…”

“…More details about the MECO(n) model system are presented in a set of publications including a chemical and meteorological evaluation (Kerkweg and Jöckel, 2012a, b;Hofmann et al, 2012;Mertens et al, 2016;and Kerkweg et al, 2018). The set-up of the simulation applied in the present study is very similar to that described by Mertens et al (2016).…”

Including vegetation dynamics in an atmospheric chemistry-enabled general circulation model: linking LPJ-GUESS (v4.0) with the EMAC modelling system (v2.53)

“…Such developments may benefit from synergies with other ongoing coupling work in the LPJ-GUESS community. When completed, these developments will extend the EMAC model into a full Earth system model including atmosphere (ECHAM5) with full chemistry (see Jöckel et al, 2010), vegetation and land surface processes (LPJ-GUESS), and an ocean component (MPIOM) (see Pozzer et al, 2011) with ocean biogeochemistry (see Kern, 2013). Furthermore, coupling efforts to COSMO (Baldauf et al, 2011) via the MESSy framework are underway.…”

“…EMAC (ECHAM/MESSy Atmospheric Chemistry) 2 originally combined the ECHAM atmospheric GCM (Roeckner et al, 2006) with the Modular Earth Submodel System (MESSy) (Jöckel et al, 2005) framework and philosophy. The model has since been extended to include expanded representations of atmospheric chemistry; a coupled ocean model with dynamic sea ice (Pozzer et al, 2011); ocean biogeochemistry (Kern, 2013); an alternative base model for the atmospheric circulation (Baumgaertner et al, 2016); regional downscaling via a two-way coupling (Kerkweg et al, 2018) with the COSMO weather forecast model (Baldauf et al, 2011); and a multitude of processes such as representations for aerosols, aerosol-radiation and aerosol-cloud (Tost, 2017) interactions, and many more (all of which are integrated via the MESSy infrastructure).…”