臺灣地區日較差的百年變化(1901-2008)

Secular Change of Diurnal Temperature Range in Taiwan (1901-2008)

黃燕儀(Yuen-Yi Ng) ； 翁叔平(Shu-Ping Weng)

《大氣科學》 39卷1期 (2011/03) Pp. 69-82

摘要

本研究透過三方向的主成份分析法(STATIS: Structuration des Tableaux A Trios Indices de laStatistique)對臺灣地區日較差(DTR: Diurnal Temperature Range)的長期變化及其和氣象參數間同時進行統計分析。研究結果顯示，(1)白天最高溫的上升趨勢小於夜晚最低溫的上升趨勢，此白天和夜晚之間的熱力不對稱，導致DTR自1901年開始呈現逐漸下降趨勢；(2)臺灣地區在長期的平均日照時數的趨勢上都呈明顯下降，然而日平均最高溫卻在增温中，此一矛盾的趨勢推測可能與人類活動所排放的氣溶膠增加有關，然而氣溶膠對日照時數的影響，主要在於氣溶膠的成雲機制，但是，根據平均雲量的分析結果顯示近年來的雲量卻在減少中，以ISCCP衛星雲資料檢測顯示，低雲族有顯著的下降趨勢，依據此結果推估，測站的總雲量或有可能顯現在衛星的低雲資料上。由此可推論，人為活動所排放的氣溶膠不是導致日照時數下降的主因。此外，根據STATIS分析百年的平均溫度記錄，本文發現(3)臺灣地區平均溫度呈上升趨勢，以冬季最為明顯，此研究結果有別於前人的分析結果；(4)臺灣地區的春季降雨有減少的現象；(5)水氣壓在夏（冬）季呈現減少（增加）趨勢，而相對濕度皆為下降趨勢。

關鍵字

日較差 ； 氣候變遷 ； 主成份分析 ； 氣溶膠

並列摘要

In this study we use a three-way principal component analysis called STATIS (Structuration des Tableaux A Trios Indices de la Statistique) to analyze the secular change of diurnal temperature range (DTR) in Taiwan and its concurrent relationships with other meteorological parameters. The results of STATIS show that: (1) the DTR has been decreasing since 1901. This is due to the inhomogeneity between a higher (lower) increasing rate of nighttime (daytime) temperature minimum, Tmin (Tmax); (2) a decreasing trend of sunshine duration (thus cloud cover) is associated with an increasing trend in Tmax. Such a paradox is interpreted as an indirect evidence of increasing anthropogenic influences such as aerosols. Nevertheless, more aerosols should have accelerated the formation of clouds thereby cloud cover. It then implies that the aerosols might not be the only factor responsible for the observed reduction of sunshine duration. Using STATIS, we further found that (3) the increasing mean temperature stands out during the boreal winter. While such a seasonality is consistent with the global trend, it differs from some previous studies; (4) a decreased trend of springtime rainfall in Taiwan, a(n) decreased (increased) trend of water vapor in summer (winter), and a decreasing relative humidity around the year are also observed simultaneously with the reduction of DTR.

並列關鍵字

Diurnal temperature range ； Climate change ； STATIS ； Aerosols