Numerical Simulation and Analysis on the Phoenix Typhoon Rainstorm Using WRF
Rainstorm caused by the Typhoon Phoenix, between July 28th and 31st 2008, is studied by using the meso-scale numerical simulation model WRF and some NCEP reanalysis data of 1¡ã¡Á1¡ãwith 6h interval. Results show that, the distribution of the SLP, wind and rain belt was simulated successfully by the WRF model. The research shows that the strong upward motion at the 600 -700hPa and 100 -200hPa of 24¡ãN and two closure centers of near 21¡ãN-22¡ãN and 31¡ãN-33¡ãN at the high troposphere induced convective cloud cluster to develop.
Numerical study of the genesis and development of typhoon WUKONG (2000) over South China Sea
The Fifth generation NCAR/PSU mesoscale nonhydrostatic model(MM5) was used to simulate the process that a tropical disturbance developed into a strong typhoon WUKONG over the South China Sea in September 2000. The MM5 model could forecast the maximum wind and intensity of the typhoon with considerable accuracy. The natural developing characteristics of South China Sea Typhoon which involved step-by-step deepening and drastic strengthening were also well simulated. Based on some diagnostic variable analysis, the potential factors on typhoon structure as well as the genesis of typhoon eye were briefly analyzed. Sensitivity experiments on sea surface temperature (SST) effect indicate that the SST is of vital importance to the genesis and development of typhoon over South China Sea. If SST is degraded by 1 degree, the simulated typhoon would have a decrease of 10?m/s on maximum wind and a nearly seven-hour delay to reach typhoon level intensity (surpass 32.8?m/s). If SST is degraded by 2 degree (with SST still being between 26 and 27 degree), the initial tropical disturbance could hardly develop into typhoon.
The potential vorticity flux through the Yucatan Channel and the Loop Current in the Gulf of Mexico
Two‐year‐long time series of current and density structure measurements across the Yucatan Channel's main section allow the calculation of the time‐dependent potential vorticity flux between the Gulf of Mexico and the Caribbean Sea, which is characterized by alternating periods of positive (cyclonic) and negative (anti‐cyclonic) vorticity influx. Periods of negative cumulative vorticity influx are related to the Loop Current extending into the Gulf of Mexico, whereas periods of positive cumulative vorticity influx relate to a Loop Current retraction, sometimes coincident with the shedding of an anti‐cyclonic eddy.