Impact of dust aerosols on Hurricane Helene's early development through the deliquescent heterogeneous freezing mode

Abstract. An ice nucleation parameterization accounting for the deliquescent heterogeneous freezing (DHF) mode was implemented into the Weather Research Forecast (WRF) model. The DHF mode refers to the freezing process for internally mixed aerosols with soluble and insoluble species that can serve as both cloud condensation nuclei (CCN) and ice nuclei (IN), such as dust. A modified version of WRF was used to examine the effect of Saharan dust on the early development of Hurricane Helene (2006) via acting as CCN and IN. The WRF simulations showed the tendency of DHF mode to promote ice formation at lower altitudes in strong updraft cores, increase the local latent heat release, and produce more low clouds and less high clouds. The inclusion of dust acting as CCN and IN through the DHF mode modified the storm intensity, track, hydrometeor distribution, cloud top temperature (hence the storm radiative energy budget), and precipitation and latent heat distribution. However, changes in storm intensity, latent heating rate, and total precipitation exhibit nonlinear dependence on the dust concentration. Improvement in the representation of atmospheric aerosols and cloud microphysics has the potential to contribute to better prediction of tropical cyclone development.