| Summary: | 碩士 === 國立臺灣大學 === 大氣科學研究所 === 95 === Starting from 2003, a new typhoon surveillance program, DOTSTAR (Dropwindsonde Observations for Typhoon Surveillance near the Taiwan Region) was launched (Wu et al. 2005). It’s expected to enhance the number of observations in the environment of hurricanes threatening North-West Pacific area.
When dealing with typhoon simulation data, it is obvious that both dropwindsonde data and satellite data are very important for the betterment of typhoon simulation. During the process, we found another method that might be able to approach to the real typhoon initial structure and improve the prediction at the same time－implanting the bogused vortex. According to the experiment results, the typhoon strength is going to be weaker and the typhoon vertical structure is easier to decay without considering the bogused vortex. All the results point out that bogused vortex plays an important role in typhoon simulation.
The results reveal that the typhoon strength is weak and typhoon vertical structure is quite decay if the experiments are without implanting the bogused vortex. Therefore, this result presents that the bogused vortex in typhoon simulation plays a very important role.
In the case study of the typhoon Magi (2004), we use both the dropwinsonde data and the bogused vortex in setting of the model initial field. And the result shows that it is a method in possibilities for improving the forecasting in typhoon intensity and possible tracks prediction. Even only consider the bogused vortex without assimilating any observation data, it still comes out a better track predictions. In the other case study of the typhoon Khanun(2005), the results point out that only consider the bogused vortex without assimilating any observation data also could comes out a better track simulation.
For Megi(2004), appropriate combination of dropwinsonde data and the bogused vortex in the model initialization have the potential to improve both the track and intensity forecasts. Even only consider the bogused vortex without assimilating any observation data, it still comes out a better track predictions. In the other case study of the typhoon Khanun(2005), the results point out that only consider the bogused vortex without assimilating any observation data also could comes out a better track simulation.
In sensitivity experiments, the simulation results reveal that MM5 3DVAR assimilation system has the sensitivity for observation inaccuracy (O) , but it’s not obvious for the sensitivity of the bogused vortex size. After removing the QuikSCAT winds near the typhoon center, the result shows the typhoon track becomes worse. More experiments and researches should be done in order to find out the best way for data quality control of QuikSCAT winds.
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