乾濕梅雨季東亞環流特性之研究

The Circulation Characteristics during Anomalous Mei-Yu Seasons

王作臺(Jough-Tai Wang) ； 黃志銘(Chi-Ming Huang) ； 胡志文(Jyh-Wen Hwu)

《大氣科學》 20卷3期 (1992/09) Pp. 267-294

摘要

本研究是探討在乾濕梅雨年間東亞環流的月平均環流分佈之差異，並分析熱力場結構和造成此差異的關係。吾人用ECMWF十年的資料配合東亞地區的雨量選擇具代表的乾濕年，分析200毫巴風場、高度場及溫度場等變數之分佈及其距平場的特性，同時也用了OLR資料來確認大區域熱力場之結構。結果顯示，在乾濕梅年高層噴流的位置和走向都與長期平均狀態的分佈不同，在濕年時噴流傾向於有西北－東北走向，此分佈加強了東亞地區的水汽梯度。溫度場及OLR的資料則顯示了在塞北地區5月時，乾年的期間該地的加熱是對流的作用，濕年則是較不屬於對流系統的影響。綜合高層環流之結構及500毫巴噴流位置之分析，吾人以兩個示意圖來表示乾濕年梅雨期間大尺度環流的三度空間之特性。

關鍵字

異常梅雨期 ； 環流特性

並列摘要

This study investigates the circulation characteristics of the upper and lower levels, and to identify the main difference of these characteristics for the anomalous Mei-Yu seasons.Data from ECMWF and the regional observational rainfall data are used. The wind, height and temperature fields are analyzed at 200, 500 and 850 hPa levels. The anomaly patterns of those variables with respect to a ten years mean are constructed. OLR data are included to further confirm the large-scale rainfall pattern. Some OLR data are also used to perform thermodymanic analyses in order to understand its impact in affecting the anomalous circulation pattern.The results indicate general position of the upper-level jet stream of anomalous Mei-Yu years are quite different from the long-term climatological mean position. During the year with moist Mei-Yu season, the upper-level jet tends to posses the direction from northwest to northeast in the East Asia region, this distribution strengths the moisture gradient in the East Asia region, while in the dry year, favorable direction is from the West. The temperature field and the OLR data indicate that in the Inner Mongolia area the thermodynamic structure are also quite different. In the early stage of dry Mei-Yu season, convective heating is strong for the temperature change, and for wet Mei-Yu season, non-convective type of heating are responsible for the temperature Change of that region.Combined with the upper and lower levels result, schematic pictures for the moist and dry year are presented to summary this preliminary result and to stimulate the discussion.

並列關鍵字

Anomalous Mei-Yu Season ； Circulation Characteristics