台灣地區春季多雨年少雨年500毫巴高度及海溫距平差異特徵之初步分析

Study on the Characteristics of 500mb Height Anomalies and SST Anomalies during Wet/Dry Years in Spring in Taiwan Area

劉復誠(Henry Fu-Cheng Liu)

《大氣科學》 15卷2期 (1987/10) Pp. 233-246

摘要

本文之主要目的是探討台灣地區春季多雨年少雨年時，500毫巴高度距平及海溫距平之差異特徵（含與正常年比較），提供長期預報上之參考。本研究所引用之月雨量資料是以中央氣象局台北、台中、台南、恆春及花蓮測站自1951至1984年間之觀測值為準，其他之500毫巴高度距平資料則取自JMA（Japan Meteorological Agency），北太平洋海溫資料則取自1979年Namias之資料。經分析500mb高度距平研究結果發現，多雨年少雨年之顯著差其特徵在於其正、負距平區分佈位置及距平梯度明顯不同，即當多少雨年時，距平梯度較大（小），且其正距平區可由我國東北向東南延伸至日本琉球一帶，但當正常年時則看不到此現象。不過由於受到大氣體系（atmospheric regimes）、槽脊配置、內動力作用（internal dynamical effect）、大氣物理特性、海水面溫度變化及東西風振盪（oscillation）之影響，500毫巴各月或各季之距平場位置或配置並非呈現出有規則之類型成可稱為大氣之intransitivity所致。如就海溫距平場分析，當冬天時，在西太平洋及東太平洋區為正距平區所據，負距平區則據在20－55°N，180°E－140°W範圍內；而少雨年時，則在西太平洋及東太平洋北部均為負距平區所據，正距平區僅佔中及東太平洋南部之小部份。至於春季之海溫距平特徵，多雨年與冬季類似，僅東太平洋區之距平梯度增加。少雨年因負距平範圍擴大，除了中太平洋為正距平區外，整個太平洋洋面幾為負距平所控制。

關鍵字

春季多雨年少雨年差異特徵

並列摘要

The main purpose of this paper is to study the characteristics of the northern hemisphere 500mb height anomalies and sea surface temperature (SST) anomalies during wet or dry years in spring in Taiwan area. The monthy rainfall data are collected from Taipei, Taichung, Tainan, Hengchun and Hualien stations employed by the Central Weather Bureau from 1951 to 1984. The other data selected are the 500mb height anomalous fields from JMA and SST anomalous fields (1951-1978, seasonal available only) from Namias (1979).Results showed that the anomalous charts of 500mb height indicated many significant different features, that is, the anomaly gradients of the wet years are much greater than dry years while the positive anomaly areas of the wet year is extending toward southeast from the northeast China to the Japan and Ryukyu islands. In addition, there is a large difference in geographical distribution of anomaly between the wet and dry years. According to the analysis of seasonal SST anomalies, there were positive SST anomalies in western and eastern Pacific and negative SST anomalies in central Pacific during pre-spring (or winter) in wet years. However, there were mostly negative SST anomaly in western Pacific and positive SST anomaly in southeastern Pacific during pre-spring (or winter) in dry year. During the spring time it is similar in distribution pattern to winter season only a little difference between the positive SST anomaly and negative SST anomaly.

並列關鍵字

differences in characteristics between wet/dry spring seasons