- 1Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research Atmospheric Trace Gases and Remote Sensing (IMKASF), Eggenstein-Leopoldshafen, Germany (valentin.hanft@kit.edu)
- 2Deutscher Wetterdienst, Offenbach, Germany
Stratospheric Ozone (O3) absorbs biologically harmful solar ultraviolet radiation, mainly in the UV-B and UV-C spectral range. When reaching the surface, such UV radiation poses a well documented hazard to human health. In order to quantify this amount of UV radiation and to make it generally understandable, the World Health Organization (WHO) has defined an UV Index [1]. It is calculated by weighting the incoming solar irradiance at surface level between 250 and 400 nanometers with their ”harmfulness” to the skin and scaling the results to values that normally range between 1 and 10, surpassing 10 for excessive UV exposure.
In our project we extend the capability of ICON (ICOsahedral Nonhydrostatic Model,[2]), the operational forecast model used by the German Meteorological Service, to provide a configuration of self-consistent UV Index forecasts that do not require external data. For this, we use ICON-ART [3],[4] with a linearized prognostic ozone scheme (LINOZ,[5]) and couple the prognostic ozone to the atmospheric radiation scheme Solar-J [6].
With this setup, we define a global test run from March to July 2022. This time frame contains distinct ozone features above Europe due to the polar vortex as well as its breakup and the transition to the summer circulation. We use the results to validate the UV Index forecast with respect to parameters that influence it, e.g. aerosol optical depth, surface albedo, or cloud cover. For the comparison we use other model data (CAMS,[7]) as well as ground-based and satellite measurements (e.g. CERES,[8]).
References:
[1] World Health Organization and World Meteorological Organization and United Nations Environment Programme and International Commission on
Non-Ionizing Radiation Protection. Global solar UV Index : a practical guide, 2002.
[2] G. Zängl, et al. The ICON (icosahedral non-hydrostatic) modelling framework of dwd and mpi-m: Description of the non-hydrostatic dynamical core. Quarterly Journal of the Royal Meteorological Society, 141(687):563–579, 2015.
[3] J. Schröter, et al. ICON-ART 2.1: a flexible tracer framework and its application for composition studies in numerical weather forecasting and
climate simulations. Geoscientific Model Development, 11(10):4043–4068,2018.
[4] D. Rieger, et al. ICON–ART 1.0 – a new online-coupled model system from the global to regional scale. Geoscientific Model Development, 8(6):1659–1676, 2015.
[5] C. A. McLinden, et al. Stratospheric ozone in 3-d models: A simple chemistry and the cross-tropopause flux. Journal of Geophysical Research: Atmospheres,105(D11):14653–14665, 2000.
[6] J. Hsu, et al. Aradiative transfer module for calculating photolysis rates and solar heating in climate models: Solar-j v7.5. Geoscientific Model Development, 10(7):2525–2545, 2017.
[7] CAMS Global Atmospheric Composition Forecasts, https://ads.atmosphere.copernicus.eu/datasets/cams-global-atmospheric-
composition-forecasts?tab=overview, 01 2025.
[8] NASA/LARC/SD/ASDC. CERES and GEO-Enhanced TOA, Within-Atmosphere and Surface Fluxes, Clouds and Aerosols 1-Hourly Terra-Aqua
Edition4A, 09 2017.
How to cite: Hanft, V., Ruhnke, R., Seifert, A., and Braesicke, P.: Prognostic Ozone For ICON: Enabling UV Forecasts, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11261, https://doi.org/10.5194/egusphere-egu25-11261, 2025.
