The upper-atmosphere extension of the ICON general circulation model (version: ua-icon-1.0)

Abstract

How the upper-atmosphere branch of the circulation contributes to and interacts with the circulation of the middle and lower atmosphere is a research area with many open questions. Inertia-gravity waves, for instance, have moved in the focus of research as they are suspected to be key features in driving and shaping the circulation. Numerical atmospheric models are an important pillar for this research. We use the ICOsahedral Non-hydrostatic (ICON) general circulation model, which is a joint development of the Max Planck Institute for Meteorology (MPI-M) and the German Weather Service (DWD), and provides, e.g., local mass conservation, a flexible grid nesting option, and a nonhydrostatic dynamical core formulated on an icosahedraltriangular grid. We extended ICON to the upper atmosphere and present here the two main components of this new configuration named UA-ICON: an extension of the dynamical core from shallow-to deep-atmosphere dynamics and the implementation of an upper-atmosphere physics package. A series of idealized test cases and climatological simulations is performed in order to evaluate the upper-atmosphere extension of ICON.Published by Copernicus Publications on behalf of the European Geosciences Union.

Interhemispheric differences of mesosphere/lower thermosphere winds and tides investigated from three whole atmosphere models and meteor radar observations

“…The Upper Atmosphere ICOsahedral Non-hydrostatic (UA-ICON; Borchert et al, 2019) atmospheric GCM covers the atmosphere from the surface to 150 km and is a vertical extension of the standard ICON configurations which have the lid usually at about 80 km. ICON is available with different physics packages to be used for numerical weather prediction (Zängl et al, 2015) and climate studies (Giorgetta et al, 2018;Crueger et al, 2018).…”

“…Here we make use of the latter. The upper atmosphere configuration extends the dynamical core from shallow-to deep-atmosphere dynamics and includes an upper atmosphere physics package with parameterizations for molecular diffusion, radiation in the Schumann-Runge bands and continuum, extreme UV, non-LTE effects and NO cooling, and chemical heating (see Borchert et al (2019) for details). The latter is necessary as UA-ICON does not calculate air chemistry interactively but uses prescribed climatologies of radiatively active species.…”

“…GAIA and WACCM-X have been cross-compared with other models (Pedatella et al, 2014b) or satellite observations (Pedatella et al, 2016;Liu et al, 2013). Recently, Borchert et al (2019) completed a first 15 years long climatology run with UA-ICON with gravity wave parameterization. UA-ICON is the upper atmosphere extension and, thus, the agreement between the meteorological analysis and the MR winds provides confidence in both data sets.…”

Reappraising the appropriate calculation of a common meteorological quantity: potential temperature

“…Wendisch et al, 2016;Voigt et al, 2017), the NASA WB-57 or ER-2 (e.g. Murphy et al, 2007;Dessler, 2002), the M-55 Geophysica (Curtius et al, 2005;Borrmann et al, 2010;Frey, 2011), balloon-borne platforms (Lary et al, 1995;Vernier et al, 2018), or satellite-based vertical profiles (e.g. Davies et al, 2006;Spang et al, 2005) require consideration of the systematic error in θ if calculated as θ c p in compliance with the definition by the WMO (1966).…”

Oblique Gravity Wave Propagation During Sudden Stratospheric Warmings

“…The deep-atmosphere dynamics account for the spherical shape of the atmosphere and include the contribution of the horizontal component of the Earth's angular velocity to the Coriolis acceleration. A detailed description and model evaluation for the R2B4 grid (horizontal mesh size of about 160 km) can be found in Borchert et al (2019). Our simulations use the R2B7 grid, which has a horizontal mesh size of about 20 km, with 180 vertical levels extending from the surface to the model top at 150 km.…”