Impact of Saharan dust as nucleating aerosols on Hurricane Helene's early development

During the summer and early fall, tropical cyclones forming in the east Atlantic Ocean are often observed to interact with a hot, dry and dusty air mass known as the Saharan Air Layer (SAL). The abundant mineral dust particles in the SAL originated from the Sahara Desert have been found to be effective cloud condensation nuclei (CCN) and ice nuclei (IN), which can potentially affect the cloud microphysics, precipitation and development of tropical cyclones. In this study, we examine the impact of Saharan dust on Hurricane Helene (2006) by performing a series of numerical experiments using the Weather Research Forecast model (WRF) version 3.1 in conjunction with multi-satellite, multi-sensor data. Remote sensing observations from CALIPSO, OMI, CloudSat, MODIS and TRMM were utilized to examine the distributions and properties of dust particles, hydrometeors and precipitation, as well as to constrain and validate the WRF model. Three groups of modeling experiments were conducted that varied either CCN concentrations, IN concentrations or both. It has been found that dust as nucleating aerosols can influence tropical cyclone development by inducing changes in storm intensity, track, thermodynamic structure, hydrometeor properties and precipitation.