Investigation of the Sensitivity of Tropical Cyclones to Aerosol Intervention during Their Early Development Stage

Tropical cyclone (TC)–related risks are rising with global warming. Increases are projected in both the proportion of intense TC and TC-associated rainfall. Future TCs may move poleward and penetrate further inland bringing heavy rain and strong winds to areas that have rarely experienced cyclones previously. Traditional measures to reduce vulnerability and exposure are unlikely to be sufficient to manage increasing risks. It is imperative to develop additional solutions. Mitigating TC hazards by aerosol seeding was proposed over two decades ago based on the impacts of aerosols on microphysics and thermodynamic processes in TC clouds. A few studies suggest that the probability of influencing TC development is highest early in their lifecycle. However, there has been little progress in this area, and the interaction between aerosols and tropical cyclogenesis remains poorly known.
In this study, we investigate the impacts of aerosols on the initiation of TCs using the Weather Research and Forecasting (WRF) model. We conduct idealized convective permitted simulations (with the finest grid spacing of 1 km) using a sophisticated spectral bin microphysics (SBM) scheme. Different particle size distributions representing both fine and coarse aerosols will be tested to determine the sensitivity of the pre-TC vortex's structure and intensity before it develops into a strong TC. The underlying mechanisms for the response of the pre-TC vortex to aerosols will be discussed. The research findings are essential to characterise potential mitigation strategies for TC risks.