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    The dynamical core of the Aeolus 1.0 statistical–dynamical atmosphere model: validation and parameter optimization


    Totz, Sonja and Eliseev, Alexey V. and Petri, Stefan and Flechsig, Michael and Caesar, Levke and Petoukhov, Vladimir and Coumou, Dim (2018) The dynamical core of the Aeolus 1.0 statistical–dynamical atmosphere model: validation and parameter optimization. Geoscientific Model Development, 11. pp. 665-679. ISSN 1991-959X

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    Abstract

    We present and validate a set of equations for representing the atmosphere’s large-scale general circulation in an Earth system model of intermediate complexity (EMIC). These dynamical equations have been implemented in Aeolus 1.0, which is a statistical–dynamical atmosphere model (SDAM) and includes radiative transfer and cloud modules (Coumou et al., 2011; Eliseev et al., 2013). The statistical dynamical approach is computationally efficient and thus enables us to perform climate simulations at multimillennia timescales, which is a prime aim of our model development. Further, this computational efficiency enables us to scan large and high-dimensional parameter space to tune the model parameters, e.g., for sensitivity studies. Here, we present novel equations for the large-scale zonalmean wind as well as those for planetary waves. Together with synoptic parameterization (as presented by Coumou et al., 2011), these form the mathematical description of the dynamical core of Aeolus 1.0. We optimize the dynamical core parameter values by tuning all relevant dynamical fields to ERA-Interim reanalysis data (1983–2009) forcing the dynamical core with prescribed surface temperature, surface humidity and cumulus cloud fraction. We test the model’s performance in reproducing the seasonal cycle and the influence of the El Niño– Southern Oscillation (ENSO). We use a simulated annealing optimization algorithm, which approximates the global minimum of a high-dimensional function. With non-tuned parameter values, the model performs reasonably in terms of its representation of zonal-mean circulation, planetary waves and storm tracks. The simulated annealing optimization improves in particular the model’s representation of the Northern Hemisphere jet stream and storm tracks as well as the Hadley circulation. The regions of high azonal wind velocities (planetary waves) are accurately captured for all validation experiments. The zonal-mean zonal wind and the integrated lower troposphere mass flux show good results in particular in the Northern Hemisphere. In the Southern Hemisphere, the model tends to produce too-weak zonal-mean zonal winds and a too-narrow Hadley circulation. We discuss possible reasons for these model biases as well as planned future model improvements and applications.

    Item Type: Article
    Additional Information: © Author(s) 2018. This work is distributed underthe Creative Commons Attribution 3.0 License. Cite as: Totz, S., Eliseev, A. V., Petri, S., Flechsig, M., Caesar, L., Petoukhov, V., and Coumou, D.: The dynamical core of the Aeolus 1.0 statistical–dynamical atmosphere model: validation and parameter optimization, Geosci. Model Dev., 11, 665–679, https://doi.org/10.5194/gmd-11-665-2018, 2018.
    Keywords: dynamical core; Aeolus; statistical–dynamical; atmosphere model; validation; parameter optimization;
    Academic Unit: Faculty of Social Sciences > Geography
    Faculty of Social Sciences > Research Institutes > Irish Climate Analysis and Research Units, ICARUS
    Item ID: 13176
    Identification Number: https://doi.org/10.5194/gmd-11-665-2018
    Depositing User: Levke Caesar
    Date Deposited: 07 Aug 2020 19:56
    Journal or Publication Title: Geoscientific Model Development
    Publisher: European Geosciences Union
    Refereed: Yes
    URI:

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