Comparison between MM5 simulations and satellite measurements during Typhoon Chanchu (2006) in the South China Sea

The fifth Pennsylvania State University and National Center for Atmospheric Research mesoscale model (MM5) is utilized to study the precipitation and wind speed during Typhoon Chanchu (2006). Five model experiments with different physical parameterizations and sea surface temperature (SST) distributions are carried out. It is found that the control experiment configured with the Blakadar boundary scheme, Resiner2 moisture, the Betts-Miller cumulus scheme and daily updated SST has the most reasonable precipitation. The MRF boundary scheme tends to simulate a dryer boundary layer and stronger vertical mixing, which can greatly reduce the intensity of tropical cyclone (TC), resulting in a smaller maximum wind speed but larger range of medium wind speed (25-30 m/s). Constant SST through the TC cycle provides more energy from ocean surface, which could cause a significant increase in TC's intensity, thus resulting in the largest overestimation on rainfall and maximum wind speed. Longitudinally-uniform SST distribution before the rapid intensification could reduce TC's intensity and heat fluxes, which can partially compensate for the overestimation of precipitation in the control experiment.