Impacts of cloud condensation and ice nuclei in the simulation of tropical cyclones

Previous studies have shown that microphysics (MP) assumptions have considerable influences on tropical cyclone (TC) simulations in high resolution or cloud-resolving models. For example, Fovell and Su (2007) performed ensemble experiments over a range of MP schemes; Pattnaik et al. (2011) examined the model's sensitivity to parameters in one single-moment MP scheme. The studies thus far, although systematic, have been mostly limited to single moment MP schemes. In this study, the double moment microphysics (DMM) schemes that predict the number concentrations (NC) for the hydrometeors in either warm-rain or mixed-phase processes are used to simulate Typhoon Fanapi (2010) with the Advanced Research Weather Research and Forecasting model (ARW-WRF). Two schemes, the six-class double moment microphysics (WDM6) and the Morrison double moment schemes are examined. Two sets of experiments are conducted to quantify model sensitivity on the NC of cloud condensation nuclei (CCN) and model sensitivity on the NC of ice nuclei (IN). The preliminary results already show that the increase of total NC of CCN evidently reduces the cyclone intensity, the gale-force wind, as well as the ice phase mixing ratios. This work may provide some insights in how the CCN and IN affect the development of TCs, in particular the asymmetric structures of the rainbands.