Numerical resea rch onintensity change and structure feature of Typhoon Rananim near shore. Ⅱ: Impact of cloud microphysical parameterization on intensity and track

In this study, we continuely discuss the impacts of cloud microphysical paramet erization scheme on the modeling intensity and track of Typhoon Rananim based on the Part I of the paper (“Impact of cloud microphysical parameterization on cl oud structure and precipitation features"). The results indicate that the cloud microphysical processes have some impact on the intensity and track of typhoon. The 36 hour maximum simulated surface wind speed is about 7 m/s greater than that of all other experiments when the cooling effect due to evaporation o f rain water is excluded; however, the model landfall location has the biggest b ias, about 150 km against the control experiment. Finally, we find that the stro ng outer simulated rainband and the vertical shear of the environmental flow are unfavorable for the deepening and maintaining of typhoon and can result in its intensity loss near the landfall. It can be easily seen that the cloud microphys ical processes can strengthen and even create the outer spiral rainbands, which can then increase the local convergence away from the TC center and prevent much moisture and energy from transportation to the inner core of the typhoon. Also, the developed outer rainbands are supposed to bring dry and cold air masses fro m the middle troposphere to the planetary boundary layer. The other branch of th e cold airflow comes from the evaporation of rain water itself in the planetary boundary layer while the droplets are falling. Thus the cutoff of the warm and moist air masses to the inner core and the invasion of cold and dry ones to the eyewall region are expected to bring about the intensity decay of the modeled t yphoon. As a result, the simulated deepening and maintaining of Typhoon Rananim during its landing should be improved through the reduction of those two kinds of model errors.