使用大尺度環境因子預報熱帶氣旋生成之特性研究

Using large-scale environmental variables to predict seasonal tropical cyclone genesis characteristics

陳建蒲(Jian-Pu Chen)

指導教授 ： 陳正達

國立臺灣師範大學/理學院/地球科學系/碩士(2012年)

摘要

自然災害中颱風造成的人員傷亡和經濟損失影響甚大，在全球氣候暖化下熱帶氣旋如何改變，一直以來都是備受廣泛討論的問題。近年來，許多研究對於熱帶氣旋主要發展區域,利用動力模式來作出颱風季節預報。
利用全球模式和區域模式模擬熱帶氣旋通常利用客觀的方法在熱帶區域偵測出類似熱帶氣旋的渦旋和渦旋的演變。不過，受到解析度的關係,模擬出的渦旋強度無法與實際觀測的相比，且就算模式解析度達到幾十公里，氣旋中心內的複雜的動力機制也無法得到完善的解釋。故另一種方法是研究大尺度環境場與實際觀測颱風個數之間的關係，發展出大尺度環境場與熱帶氣旋生成相關的潛在生成指數,則可以簡單的利用模式模擬出的環境場作颱風季節預報。
本篇研究目的是使用不同的熱帶氣旋潛在生成指數來比較季節預報上的可行性，並使用不同的熱帶氣旋潛在生成指數應用在ECHAM4和ECHAM5全球模式。以季節循環、空間分佈、年際變化來探討模式的模擬的能力，也分析各項環境條件對於熱帶氣旋生成的影響。

關鍵字

熱帶氣旋 ； 熱帶氣旋潛在生成指數

並列摘要

Typhoon is one of the most ruinous natural catastrophes that cause loss of life and colossal property damage. How tropical cyclone (TC) would change in a warmer climate has been a controversial issues topic. In recent years, many studies have showed reasonable skill in forecasting seasonal typhoon activities over major ocean basins using dynamical models.
TC simulations with global and regional climate models typically use detection and tracking scheme to find typhoon-like vortices and their evolution in the tropical region and beyond. Nevertheless, the intensity of vortices in the model is much weaker than the observation. The complicated inner core dynamics of typhoon can not be properly resolved by even with model resolution of few tens of kilometer. It raised some doubts on whether it is realistic to compute the TC statistics based on their analog simulated in the model. An alternative approach is to study the empirical between large-scale environmental and the observed number of TC genesis. By developing indices that link TC activities with modeled large-scale circulation, one can simply use modeled environment condition to make the seasonal typhoon forecast.
Our research aims on using different TC genesis potential indices (GPI) developed in previous literature for experimental tropical cyclone seasonal activity prediction. ECHAM4 and ECHAM5 climate models forced by observed sea surface temperature and sea ice condition are used to test the potential skill on the model simulated large-scale environmental variables to be used in various GPI. We would compare the model’s ability in capturing the seasonal evolution, interannual variability, and long-term trend when different GPIs are used.

並列關鍵字

Tropical cyclone ； Genesis potential indices

參考文獻

梁信謙，2011 : 系集動力模式對於西北太平洋之颱風季節模擬。國立臺灣師範大學地球科學系碩士論文。

Bister, M., and K. A. Emanuel, 1998: Dissipative heating and hurricane intensity. Meteor. Atmos. Phys., 52, 233–240.

Bister, M., and K. A. Emanuel, 2002a: Low frequency variability of tropical cyclone potential intensity. 1. Interannual to interdecadal variability.J. Geophys.Res.,107,4801, doi:10.1029/2001JD000776.

Bister, M., and K. A. Emanuel, 2002b: Low frequency variability of tropical cyclone potential intensity. 2. Climatology for 1982–1995. J. Geophys. Res., 107, 4621, doi:10.1029/2001JD000780.

Camargo, S. J., A. G. Barnston, and S. E. Zebiak, 2005: A statistical assessment of tropical cyclone activity in atmospheric general circulation models. Tellus, 57A: 589-604.