Aerosols-Cloud-Microphysics Interactions in Tropical Cyclones using the WRF-ARW model with a new Aerosol-Aware Microphysics Scheme

Cloud microphysics processes are factors influencing tropical cyclones evolution. Questions remains unanswered about the role of aerosols (e.g. dust, sulphate and sea salt) in those processes. For example: What is the link between dust and cloud microphysics quantities? Does dust influence the vertical distribution of latent heating? Does dust affect precipitation rates? What are the dominant factors and in which sectors of the tropical cyclone? To address some of the questions in-situ microphysics measurements from the NASA DC-8 aircraft were obtained during the GRIP 2010 field campaign. A total of four named storms (Earl, Gaston, Karl and Mathew) were sampled. Earl presented the excellent opportunity to study aerosols-cloud-microphysics interactions.

To assist in the interpretation of the microphysics observations, high resolution numerical simulations of hurricane Earl were performed using the Weather Research and Forecasting (WRF-ARW) model with the new Aerosol-Aware bulk microphysics scheme. This new version of Thompson scheme includes explicit activation of cloud condensation nuclei (CCN) from a major CCN source (i.e. sulfates and sea salt) and explicit ice nucleation (IN) from mineral dust. Three simulations are performed: (1) Control case with the old Thompson scheme, (2) Aerosol-Aware case, and (3) Sensitivity case varying the initial concentration of dust. Preliminary results of model simulations will be presented along with aircraft observations.