POF - A prognostic ozone scheme for ICON: Enabling UV predictions. 

Motivation: 

Stratospheric ozone protects life on Earth from harmful UV radiation. As shown in the image, the intensity of UV radiation reaching the ground is reduced by the ozone layer. However, the ozone layer is highly variable and is also modified by humans through chlorofluorocarbons (CFCs). Therefore, knowledge of both ground-level UV intensity and stratospheric ozone content at weather and climate scales is important for humans. 

Project:

In POF, the forecast functionality of ICON(-ART) will be extended with respect to ozone distribution and (near-ground) UV fluxes. For this purpose, an existing prognostic ozone scheme is optimised, which then enables self-consistent forecasts of meteorology and ozone. These are then the prerequisite for a correct UV forecast. The prognostic ozone scheme is complemented by a simple data assimilation scheme to generate initial conditions for the ozone predictions. This project thus develops an ICON extension that provides an independent, consistent UV forecast with very little computational effort.

Prospects: 

In addition, the framework developed in this project allows for easy implementation of other chemical tracers. The calculation of actinic fluxes (required for chemistry) is made possible by considering prognostic ozone. Another use case is, for example, methane (CH4). The analysis and forecast of the methane distribution would support the planned DWD observation network and the informative value of its results.

In addition, the consideration of prognostic (stratospheric) ozone could also enable better seasonal forecasts due to the possibility of using optimised flow-consistent ozone distributions in the radiation scheme.