Prognostic Ozone For ICON: Enabling UV Forecasts

Abstract

<p><span>Stratospheric ozone (O</span><span>3</span><span>) absorbs biologically harmful solar ultraviolet radia</span><span>tion, mainly in the UV_B and UV_C spectral range. When reaching the surface, </span><span>such UV radiation poses a well documented hazard to human health. In order to</span> <span>quantify this amount of UV radiation and to make it generally understandable, t</span><span>he World Health Organization has defined an UV Index[1].</span> <span>It is calculated </span><span>by weighting the incoming solar irradiance at surface level between 250 and 400</span> <span>nanometers with their ”harmfulness” to the skin and scaling the results to values </span><span>that normally range between 1 and 10, surpassing 10 for excessive UV exposure.</span></p><p><span>Implementing UV Index forecasts in numerical weather prediction (NWP) </span><span>models allows to alert the public in time if special care for sun protection needs</span><br><span>to be taken. The German Weather Service (DWD) uses its NWP model ICON </span><span>(ICOsahedral Nonhydrostatic Model)[2] to offer such a forecast for Germany[3]</span><br><span>using external data such as ozone forecasts by the Royal Dutch Weather Service </span><span>(KNMI) and radiation lookup tables[4].</span></p><p><br><span>In our project we extend the capability of ICON to provide a configura</span><span>tion of self-consistent UV Index forecasts that do not require external data. </span><span>For this, we use ICON-ART[5],[6] with a linearized ozone scheme (LINOZ)[7]</span> <span>and couple the prognostic ozone to the atmospheric radiation scheme Solar-J[8].</span><br><span>Here we present the current state of our UV Index forecast system and </span><span>compare our results to available reference data.</span></p><p><span>References:</span></p><p><span>[1] World Health Organization, World Meteorological Organization, United Nations Environment Programme, and International Commission on Non-<br>Ionizing Radiation Protection. Global solar uv index : a practical guide,2002.</span></p><p><span>[2] Günther Zängl et al.. The icon (icosahedral non-hydrostatic) modelling framework of dwd and mpi-m:<br>Description of the non-hydrostatic dynamical core. Quarterly Journal of the Royal Meteorological Society, 2015.</span></p><p><span>[3] https://kunden.dwd.de/uvi/index.jsp.</span></p><p><span>[4] Henning Staiger and Peter Koepke. Uv index forecasting on a global scale. Meteorologische Zeitschrift, 2005.</span></p><p><span>[5] D. Rieger et al.. Icon–art 1.0 – a new online-coupled model system from the global to regional scale. Geoscientific Model Development, 2015.</span></p><p><span>[6] 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. </span><span>Geoscientific Model Development, 2018.</span></p><p><span>[7] C. A. McLinden et al. Stratospheric ozone in 3-d models: A simple chemistry and the cross-tropopause flux. Journal of Geophysical Research: Atmospheres, 2000</span></p><p><span>[8] J. Hsu, M. J. Prather et al.. A radiative transfer module for calculating photolysis rates and solar heating in climate models: Solar-j v7.5. Geoscientific Model Development, 2017.</span></p>