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Long Term Change of Diurnal Temperature Range in Taiwan and its Relationship with Atmospheric Hydrologic Processes
Yuen Yi Ng
Diurnal temperature range
Principal component analysis
|Abstract:|| 本研究使用中央氣象局21個測站的多重氣象變數，根據其資料豐度分別截取了1896至2008﹔1901至2008﹔以及1970至2008年等3個時間窗區的月觀測資料，透過Mann-Kendall（MK）test、赫斯特指數和三方向的主成份分析（STATIS: Structuration des Tableaux A Trios Indices de la Statistique）對台灣地區日較差的長期變化及其與大氣－陸表水文過程的關係進行統計分析。研究結果顯示，(1)台灣地區平均溫度的上升趨勢，以冬季最為明顯；(2)白天最高溫的上升趨勢小於夜晚最低溫的上升趨勢，此一熱力在日夜間的不對稱導致日較差（DTR: Diurnal Temperature Range）呈現下降趨勢；(3)日照時數和雲量變化是影響最高溫的直接因素。本研究却發現，日照時數和白天雲量有減少的趨勢。此一矛盾的趨勢推測可能與人類活動所排放的懸浮微粒增加有關；(4)累積降雨量雖無統計上明顯的變化，然而累積降雨時數在北部地區則有漸減的現象，暗示了北台灣降雨極端值的長期趨勢有增大的潛勢。此外，應用STATIS分析百年的降雨記錄，本文發現(5)台灣地區的春季降雨有減少的現象；(6)水氣壓在台灣北(南)部地區呈現減少(增加)趨勢，然而相對濕度則南北皆為下降趨勢。|
In this report, we analyze and discuss the overall data based on the applied difference analysis method. We have obtained the monthly data from 21 Taiwan meteorology stations operated by Central Weather Bureau and have divided them into three sets time series: we show the short term trend using station data sets from the period of 1970 to 2008, and present the long term trend using station data sets from the period of 1896 to 2008 and from 1901 to 2008. We analyze the long term change of diurnal temperature range (DTR) in Taiwan and its relationship with atmospheric-hydrologic processes on the basis of three different methods: Mann-kendall (MK) test, Hurst exponent, and principal component analysis (STATIS: Structuration des Tableaux A Trios Indices de la Statistique). The results of current study show that: (1) a steady increase of the average temperature is found in Taiwan especially during the wintertime; (2) the reduction of diurnal temperature range is due to the asymmetric change between the daytime maximum and nighttime minimum; a faster increasing rate is associated with the nighttime minimum; (3) sunshine duration and cloud cover have a direct thermal effect on daytime maximum; however, a decreasing trend is found not only in the sunshine duration but also in the daytime cloud cover. Such a paradox is interpreted as the evidence of anthropogenic influences due to emissions and aerosols; (4) although the increased trend of cumulative precipitation is statistically insignificant, the duration of it is significantly decreasing in northern Taiwan. It thus suggests an increasing intensity of rainfall. The results of STATIS also reveal (5) a decreased trend of springtime precipitation in northern Taiwan, and (6) a decreased (an increased) trend of water vapor in northern (southern) Taiwan whereas an islandwide decreased trend is found in the field of relative humidity.
|Appears in Collections:||學位論文|
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