Atmosphere Ice Ocean

    WG AIO


    The WG Atmosphere Ice Ocean (AIO) aims to build up regional Earth system models by coupling the atmosphere in the COSMO-CLM and ICON-CLM with other components of the climate system such as ocean, sea ice, hydrology, etc. and investigate their interaction and feedback.

    Regional climate models (RCMs) are tools for dynamical downscaling coarse results from global climate circulation models (GCMs), which are nowadays mainly coupled atmosphere-ocean models (AOGCMs). Ideally, RCMs should be able to determine the regional climate without the influence of the GCMs, except at the lateral boundaries. However, presently this is not the case for COSMO-CLM/ICON-CLM, since the lower boundary values over the sea are taken from the AOGCMs. This has a major impact on the quality of the regional model simulations as shown already for the Baltic Sea, the North Sea and the Mediterranean Sea. To overcome this problem regional coupled atmosphere-ocean models may be used for climate simulations. Several groups in the CLM-Community are working on the coupling of a regional ocean to COSMO-CLM/ICON-CLM.

    Wiki 🔑AIO


    • Improve the representation of the ocean and the interaction with the atmosphere in the COSMO-CLM (Hereon; IOW; Goethe University Frankfurt, BTU Cottbus) and in the ICON-CLM (Hereon; DWD; IMS; CMCC) over the North-Baltic Sea and Mediterranean Sea

    • Simulating polynya processes in the Laptev Sea and the Weddell Sea with a fully coupled A-I-O model (University Trier)

    • Assess the added value of high-resolution climatic hindcasts and scenarios for the Mediterranean when using coupled atmosphere-ocean models (IMK-TRO, KIT)

    • To get better accuracy, since in the CIRA simulations the lower boundary values over the sea are taken from the global coupled model CMCC-MED. A better regional representation of the Mediterranean Sea is also important in order to increase the accuracy also for climate simulations of the Alpine space (CIRA)

    • Carry out simulations over the Southern Ocean to investigate seasonal simulations covering the confluence region of the Brazil and Malvinas currents, where many oceanic eddies occur (C2SM-ETHZ). Thereby two major questions are addressed: (1) What is the impact of the highly resolved SST on fluxes between the atmosphere and the ocean and on the lower troposphere? Are highly resolved SSTs required to realistically represent fluxes of heat and freshwater in that region? (2) How are these processes affected by the coupling between the atmosphere and the ocean?

    Considered domains

    The red boxes give a rough idea of the domains, however, they do not represent the exact boundaries.

    Model components

    Models: Ocean / Ice / Runoff / Wave





    NEMO / LIM3 / HD

    North Sea, Baltic Sea

    Ha Hagemann, Stefan Hagemann



    TRIM / CICE / HD

    North Sea, Baltic Sea

    Ha Hagemann, Stefan Hagemann


    development stopped

    NEMO / LIM3 / WAM

    North Sea, Baltic Sea

    Anne Wiese, Ha Hagemann


    no update available

    NEMO / SI3

    North Sea, Baltic Sea

    Vera Maurer




    Baltic Sea

    Sven Karsten, Markus Meier




    Mediterranean Sea

    Neelam Rajput, Bodo Ahrens




    Mediterranean Sea

    Elykom Vadislavsky, Pavel Khain




    Mediterranean Sea

    Angelo Campanale, Paola Mercogliano




    Mediterranean Sea

    Andreas Will

    BTU Cottbus

    no update available


    Arctic, Laptev Sea, Svalbard

    Oliver Gutjahr


    no update available

    NEMO / LIM3

    (Western) Mediterranean, Northeast Atlantic

    Hendrik Feldmann, Gerd Schädler


    no update available


    Southern Atlantic

    David Byrne, Lukas Papritz


    no update available

    Ocean model /

    CORDEX East Asia

    Donghyun Lee

    Pohang Uni. of Sci. & Tech., South Korea

    no update available



    Meeting and Location


    2023/09/21CLM-Assembly Online Meeting🔑Minutes


    CLM-Assembly Online Meeting



    CLM-Assembly Online Meeting



    ICCARUS online



    CLM-Assembly Online Meeting



    CLM-Assembly in Karlsruhe



    ICCARUS in Offenbach



    CLM-Assembly in Graz



    ICCARUS in Offenbach



    CLM-Assembly in Lüneburg



    CLM-Community Assembly in Zürich


    COSMO/CLM Seminar in Offenbach


    CLM-Community Assembly in Leuven



    COSMO/CLM Seminar in Offenbach


    CLM-Community Assembly in Cava de' Tirreni


    COSMO/CLM Seminar in Langen


    Startup Meeting in Berlin


    See Material



    Karsten, S., Radtke, H., Gröger, M., Ho-Hagemann, H. T. M., Mashayekh, H., Neumann, T., and Meier, H. E. M. (2024): Flux coupling approach on an exchange grid for the IOW Earth System Model (version 1.04.00) of the Baltic Sea region, Geosci. Model Dev., 17, 1689–1708, https://doi.org/10.5194/gmd-17-1689-2024


    Grayek, S., Wiese A. , Ho-Hagemann, H. T. M., Staneva, J., Added Value of Including Waves into Coupled Atmosphere-Ocean Model System within the North Sea Area, Frontiers in Marine Science, https://doi.org/ 10.3389/fmars.2023.1104027

    Hagemann, S., Ho-Hagemann, H. T. M., and Hanke, M.: The Hydrological Discharge Model - a river runoff component for offline and coupled model applications (5.2.2), Zenodo, https://doi.org/10.5281/zenodo.10405875, 2023.


    Ho-Hagemann, H.T.M. (2022). The OASIS3-MCT Coupling Interface for ICON-CLM (1.0.0). Zenodo. https://doi.org/10.5281/zenodo.5833118

    ​Rockel, B. (2022). SPICE (Starter Package for ICON-CLM Experiments) (1.1). Zenodo.https://doi.org/10.5281/zenodo.6517710


    Gröger, M., Dieterich, C., Haapala, J., Ho-Hagemann, H.T.M., Hagemann, S., Jakacki, J., May, W., Meier, H.E.M., Miller, P.A., Rutgersson, A., & Wu, L. (2021): Coupled regional Earth system modeling in the Baltic Sea region. Earth Syst. Dynam., 12, 939–973, doi:10.5194/esd-12-939-2021

    Hagemann, S., and Ho-Hagemann, H.T.M.: The Hydrological Discharge Model - a river runoff component for offline and coupled model applications (5.0.0), Zenodo. https://doi.org/10.5281/zenodo.4893099, 2021.

    Pham, T. V., Steger, C., Rockel, B., Keuler, K., Kirchner, I., Mertens, M., Rieger, D., Zängl, G., and Früh, B.: ICON in Climate Limited-area Mode (ICON release version 2.6.1): a new regional climate model, Geosci. Model Dev., 14, 985–1005, https://doi.org/10.5194/gmd-14-985-2021, 2021.


    Hagemann, S., Stacke, T., and Ho-Hagemann, H.T.M.: High resolution discharge simulations over Europe and the Baltic Sea catchment, Frontiers in Earth Science, 8, https://doi.org/10.3389/feart.2020.00012, 2020.

    Ho-Hagemann, H. T. M., Hagemann, S., Grayek, S., Petrik, R., Rockel, B., Staneva, J., Feser, F., and Schrum, C.: Internal model variability of the regional coupled system model GCOAST-AHOI, Atmosphere, 11(3), 227. https://doi.org/10.3390/atmos11030227, 2020.

    Wiese, A., Staneva, J., Ho-Hagemann, H. T. M., Grayek, S., Koch, W., and Schrum, C.: Internal Model Variability of Ensemble Simulations with a Regional Coupled Wave-Atmosphere Model GCOAST, Frontiers in Marine Science, 7, 596843, https://doi.org/10.3389/fmars.2020.596843, 2020.


    Wiese, A., Stanev, E., Koch, W., Behrens, A., Geyer, B., and Staneva, J.: The Impact of the Two-Way Coupling between Wind Wave and Atmospheric Models on the Lower Atmosphere over the North Sea, Atmosphere 2019, 10, 386, https://doi.org/10.3390/atmos10070386, 2019.


    ​Ho-Hagemann, H.T.M., & Rockel, B. (2018): Einfluss von Atmosphäre-Ozean Wechselwirkungen auf Starkniederschläge über Europa. In: Lozán, J.L., Breckle, S.-W., Graßl, H., Kasang, D., & Weisse, R. (Hsg.): Warnsignal Klima: Extremereignisse, www.klima-warnsignale.uni-hamburg.de/wetterextreme/

    Staneva, J., Schrum, C., Behrens, A., Grayek, S., Ho-Hagemann, H., Alari, V., Breivik, Ø., and Bidlot, J.-R.: A North Sea - Baltic Sea regional coupled models: atmosphere, wind, waves and ocean. In: Buch, E., Fernández, V., Eparkhina, D., Gorringe, P., and Nolan, G. (Eds.): Operational Oceanography serving Sustainable Marine Development, Proceedings of the Eight EuroGOOS International Conference, 516 pp, ISBN 978-2-9601883-3-2, 2018.


    Akhtar, N., J. Brauch, B. Ahrens (2017): Climate Modeling over the Mediterranean Sea: Impact of Resolution and Ocean Coupling. Clim. Dyn. DOI 10.1007/s00382-017-3570-8

    Ho-Hagemann, H. T. M., Gröger, M., Rockel, B., Zahn, M., Geyer, B., and Meier, H. E. M.: Effects of air-sea coupling over the North Sea and the Baltic Sea on simulated summer precipitation over Central Europe, Clim Dyn 49, 3851-3876. https://doi.org/10.1007/s00382-017-3546-8, 2017.

    Pham, Trang Van; J. Brauch, B. Früh, B. Ahrens (2017): Simulation of snowbands in the Baltic Sea area with the coupled atmosphere-ocean-ice model COSMO-CLM/NEMO. Met. Z., doi: 10.1127/metz/2016/0775

    Rockel, B., J. Brauch, O. Gutjahr, N. Akhtar, H.T.M. Ho-Hagemann (2017): Gekoppelte Modellsysteme: Atmosphäre und Ozean. Promet - Meteorologische Fortbildung, 99, 65-75

    Wahle, K., Staneva, J., Koch, W., Fenoglio-Marc, L., Ho-Hagemann, H.T.M., and Stanev, E.V.: An atmosphere–wave regional coupled model: improving predictions of wave heights and surface winds in the southern North Sea, Ocean Sci., 13, 289-301, https://doi.org/10.5194/os-13-289-2017, 2017.

    Will, A., Akhtar, N., Brauch, J., Breil, M., Davin, E., Ho-Hagemann, H.T.M., Maisonnave, E., Thürkow, M., and Weiher, S.: The COSMO-CLM 4.8 regional climate model coupled to regional ocean, land surface and global earth system models using OASIS3-MCT: Description and performance, Geosci. Model Dev. 2017, 10, 1549–1586. Doi:10.5194/gmd-10-1549-2017, 2017.


    Byrne, D., M. Münnich, I. Frenger, N. Gruber (2016): Mesoscale atmosphere-ocean coupling enhances the transfer of wind energy into the ocean, Nature Communications 7, doi:10.1038/ncomms11867

    Ruti P.M., S. Somot, F. Giorgi, C. Dubois, E. Flaounas, A. Obermann, A. Dell'Aquila, G. Pisacane, A. Harzallah, E. Lombardi, B. Ahrens, N. Akhtar, A. Alias, T. Arsouze, R. Aznar, S. Bastin, J. Bartholy, K. Béranger, J. Beuvier, S. Bouffies-Cloché, J. Brauch, W. Cabos, S. Calmanti, J.-C. Calvet, A. Carillo D. Conte, E. Coppola, V. Djurdjevic, P. Drobinski, A. Elizalde-Arellano, M. Gaertner, P. Galàn, C. Gallardo, S. Gualdi, M. Goncalves, O. Jorba, G. Jordà, B. L'Heveder, C. Lebeaupin-Brossier, L. Li, G. Liguori, P. Lionello, D. Maciàs-Moy, P. Nabat, B. Onol, B. Rajkovic, K. Ramage, F. Sevault, G. Sannino, M.V. Struglia, A. Sanna, C. Torma, V. Vervatis (2016): MED-CORDEX initiative for Mediterranean Climate studies. Bull. of the American Meteorological Society, 97(7), 1187-1208, doi: 10.1175/BAMS-D-14-00176.1


    Ho-Hagemann, H. T. M., Hagemann, S., and Rockel, B.:  On the role of soil moisture in the generation of heavy rainfall during the Oder flood event in July 1997, Tellus A 2015, 67, 28661, https://doi.org/10.3402/tellusa.v67.28661, 2015.


    Akhtar, N.J., J. Brauch, A. Dobler, K. Béranger, B. Ahrens (2014): Medicanes in an ocean-atmosphere coupled regional climate model. Nat. Hazards Earth Syst. Sci., 14, 2189-2201, doi:10.5194/nhess-14-2189-2014

    ​Pham, T.V., J. Brauch, C. Dieterich, B. Früh, B. Ahrens (2014):

    New coupled atmosphere-ocean-ice system COSMO-CLM/NEMO: On the air temperature sensitivity on the North and Baltic Seas. Oceanologia, 56(2), 167-189, doi:10.5697/oc.56-2.167


    Ho-Hagemann H, Rockel B, Kapitza H and Geyer B (2013): COSTRICE-an atmosphere-ocean-sea ice model coupled system using OASIS3, HZG Report (2013-5), 24pp


    Hagemann, S., and Dümenil, L.: A parametrization of the lateral waterflow for the global scale, Climate Dyn., 14, 17–31, https://doi.org/10.1007/s003820050205, 1998.

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    Jennifer Brauch (2016 - 2021)

    Bodo Ahrens (2014 - 2016)

    Burkhardt Rockel (2010 - 2014)

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