Effects on the dynamical and microphysical structures of tropical storms in ICON

Tropical cyclones are impressive phenomena of tropical meteorology and form spatially highly organised structures. To shed more light on microphysical sensitivities and dynamical structure when modelling these storms, we selected the hurricane Paulette to simulate one week of the storm’s evolution with the German weather and climate model ICON in a limited area mode.

Hurricane Paulette occurred in the North-Atlantic basin in September 2020 and is the longest-lasting tropical cyclone of that year (7-22nd September).

In our experiments perturbations in the Cloud Condensation Nuclei (CCN) type and concentration are explored as well as the vertical resolution of the model. Additionally, the horizontal grid spacing is reduced to hectometre scale (300m) to get a more detailed look into the hurricane.

Here we present some key findings for the wind speed, surface pressure and cloud related variables along the hurricane track, next to how accurate the track is compared to NOAA observational data. Lastly, the influence of the introduced perturbations and reduction in resolution, horizontal and vertical, on radiation fluxes at the top-of-the-atmosphere in the simulated area is assessed. It can be stated that in most simulations the strength of Paulette is underestimated compared to the observations and the model produces to little ice to accurately represent the hurricane clouds in comparison to satellite observations.