Numerical Simulation Of Cloud Microphysical Features Of Landfall Typhoon Krosa(0716)

Typhoon KROSA in 2007 is performed using mesoscale numerical model GRAPES in which a two-moment mixed-phase microphysics scheme has been implanted. In-situ rainfall observations, radar and satellite data are also used to analyze the precipitation structure and microphysics features. It is shown that low-level jet and unstable temperature stratification provide this precipitation process with favorable weather condition. Heavy rainfall centers locate at north and east part of KROSA, and the maxima of 6-hour total rainfall during model time are more than 100mm. The quantities of column solid water and column liquid water are basically the same, which indicates that ice-phase process has played an important role in precipitation formation. Strong convection occurs in the eyewall around cyclone center according to the CloudSat data. Based on the simulation result, heavy precipitation in the northeast part of typhoon is triggered by convective cloud, and the strongest updraft appears under melting layer. In the southwest part of KROSA , precipitation intensity is rather uniform. Upward movement center here exists in high-level cold cloud, and is very conducive to the formation and growth of ice particles.A series of numerical experiments are designed to test the sensitivity of landfall typhoon and its precipitation to varying cloud microphysics and latent heat release, using the results presented before as a control run. It is found that typhoon track is very sensitive to varying cloud microphysics processes and latent heat release, while typhoon intensity shows little sensitivity to different microphysics processes. It is also shown that, the cloud structures of simulated cyclones can be quite different with different cloud microphysics processes. Warm rain process produces fairly uniform precipitation, and graupel particles play an important role in the formation of local heavy rainfall and the maintenance of spiral rainbands. In this case, hail process does not have much influence on cloud structure and surface precipitation. The impact of latent heat on KROSA is a combination result of several cloud physics process. Without consideration of latent heat will result in warm core intensification, eyewall compaction, slower decay and longer lifetime. Overall, latent heat produces downdrafts and cools down the air in landfall typhoon, while downdrafts and cold air can be referred to as main prohibiting factors to the formation and development of hydrometeors.