衛星資料在夏季午後對流潛勢環境之初步分析

A Preliminary Analysis in Potential Environment of Convections in the Summer by Using Satellite Data

李紀恩(Ji-En Li) ； 劉崇治(Chung-Chih Liu) ； 趙俊傑(Chun-Chieh Chao) ； 葉南慶(Nan-Ching Yeh)

《大氣科學》 33卷3期 (2005/09) Pp. 189-214

摘要

台灣地區夏季期間，常有劇烈午後熱對流的發生，這種對流系統發生的機制，是氣象學家及預報人員相當感興趣的議題之一。由於午後熱對流發展快速，單單從傳統的觀測資料是不容易做到事前的預警，因此往往造成人、事、物的損傷。尤其台灣地區四面臨海，建立衛星觀測資料之應用能力更顯得重要。本研究主要目的是，建立一套適合台灣附近區域使用的NOAA(National Oceanic and Atmospheric Administration)繞極衛星大氣溫濕垂直剖面反演方法，並將其結果應用在夏季午後熱對流發生之有利大氣條件分析。 在大氣溫濕剖面反演結果顯示，NOAA衛星反演850、700、500、400及300hPa大氣溫度（露點）的均方根誤差及相關係數分別為2.47(4.43)、2.18(3.13)、1.76(5.07)、1.97(5.73)、2.05℃(3.73℃)及0.83、0.82、0.71、0.76、0.67。在溫度方面，雲覆蓋量小於50%的情況下，各層均方根誤差平均約2.0℃，標準差約0.5℃，在露點方面，雲覆蓋量小於50%的情況下，各層均方根誤差平均約4.3℃，標準差約0.9℃。
本研究利用衛星資料計算台灣地區附近大氣穩定指數及500hPa水氣含量，並將其結果應用在實際的個案分析之中，結果顯示：大氣中水氣含量的多寡及穩定度的狀態，對夏季午後對流系統的生成與發展同樣的重要。此外由2003年6~9月441個樣本分析，推導出台灣地區夏季午後對流降水發生機率的預報模式，可做為對流降水出現與否的預報參考，初步的分析結果顯示準確率約87.36%，此結果顯示本研究建立之指數確可提升午後熱對流的預報能力。

關鍵字

大氣溫濕剖面 ； 大氣穩定指數 ； 水氣含量 ； 午後對流

並列摘要

Intense convections often occur over the Taiwan area during the afternoon in summer. The relevant mechanisms of this weather system are strongly attracts the attention of meteorologists and forecasters. Since the development of the afternoon convection is very rapid usually, the traditional observations can not provide an early warning, which often results in serious damages to the environment and livelihood of people. Due to the lack of traditional radiosonde observations, it is very important to emphases the applications in satellite monitoring. The major purpose of this research is to establish a method for the polar-orbiting NOAA-15 satellite to retrieve the profiles of temperature and dew
point near the Taiwan areas, then we apply this result in the analysis of convection's environment during the afternoon in summer.
The results show that the root mean square errors and correlation coefficients of temperature (the
dewpoint) are 2.47(4.13)、2.18(3.13)、1.76(5.07)、1.97(5.73)、2.05(3.73) and 0.83、0.82、0.71、0.76、0.67 respectively. Besides, we utilize the NOAA satellite data to derive the distribution of the atmospheric stability and moisture at 500hPa around Taiwan areas. It shows that the enough atmospheric moisture content and the degree of stability are both important to convective systems' gensis during the afternoon in summer. Moreover, a model to predict the possibility of convection over the Taiwan areas during the afternoons of summer were proposed by using satellite data. It can be applied to predict if convections will appear.

並列關鍵字

Profile of temperature dew point ； Atmospheric instability ； Moisture content