On Cyclogenesis over the East China Sea
| Autor: | Sheng, Yang-Fan, 盛揚帆 |
|---|---|
| Rok vydání: | 1997 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 85 Due to the lower latitude of location and smaller scale when generated, the development of cyclones over the East China Sea can not be explained simply by baroclinic instability. The cyclogenesis and development of cyclones over the East China Sea may have many complicate dynamical and thermal dynamical mechanisms. The mechanisms include the terrain effect induced by mountains on the west side of the East China Sea, the large gradient of sea surface temperature in cold seasons and continual supply of water vapor over ocean. So, it is interesting to find the main mechanism of cyclogenesis over the East China Sea. The understanding of East China Sea cyclogenesis will also help us to realize the weather of Taiwan area in winter and spring. This study wants to find the main mechanism of cyclogenesis and development of cyclones over the East China Sea by using the global analysis data and model simulations. The result shows that the development of cyclones includes two stages. Cyclones will occur over the East China Sea as the result of the interactions of baroclinity of low-level atmosphere, disturbances of low-level atmosphere and latent heat release. Latent heat release is the most important mechanism at this stage. Baroclinic instability will become the most important mechanism at the stage when cyclones move out the East China Sea and toward high latitude. Latent heat release is the key factor in the lifetime of East China Sea cyclones. Cyclone intensity will decrease or even vanish when the simulations remove the effect of latent heat release. Latent heat release will also help to amplify the cyclones even at the stage when the baroclinic instability is the most important mechanism. Latent heat release can increase the size of cyclones from meso- scale when occurred over the East China Sea to synoptic scale when well developed. There will be more interactions between cyclones and environmental atmosphere when cyclones have larger scale. So, latent heat release can increase the probabilities that cyclones will continue to develop with synoptic forcing when cyclones move out the East China Sea. Latent heat release plays an important role that chaining the two development stages of cyclones. It help cyclones to transfer from the stage with thermal instability over the East China Sea to the stage with baroclinic instability at higher latitude. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
| Externí odkaz: |
|