洪致文黃婉如Hung, Chih-WenHuang, Wan-Ru吳珮縈Wu, Pei-Ying2023-12-082023-08-112023-12-082023https://etds.lib.ntnu.edu.tw/thesis/detail/ee2ebfd184b0d5629dd05ad9ea49edba/http://rportal.lib.ntnu.edu.tw/handle/20.500.12235/121059本研究利用臺灣測站資料及全球網格再分析資料進行分析，發現臺灣在夏季降水量與溫度之關係有顯著負相關，春季有較弱負相關，而秋冬多為不顯著的相關性，而在亞洲季風區內也有類似現象，另外在整個北半球區域，越往低（高）緯度地區降水量與溫度之關係全年幾乎呈現負（正）相關。再加入風場資料分析降水量與溫度之關係在季節上的變化，發現在亞洲季風區內，日本、臺灣及臺灣附近之海域在有北風分量時，降水量與溫度之關係為正相關，也就是秋季及冬季的時候；在有南風分量時，降水量與溫度之關係為負相關，也就是春季及夏季時，隱含著這樣的變動關係和季風與季節轉變有關。本研究另外加入Outgoing Longwave Radiation（OLR）與海平面氣壓資料來分析造成降水量與溫度這兩者關係之機制，推測低緯度地區呈現負相關原因主要由降水型態所影響，在夏季若有對流發生產生降水時，雲層將阻擋日照使溫度下降，因此為降水量越多溫度越低的負相關；高緯度地區呈現正相關原因可能為該地區溫度低，無法有足夠水氣與龐大蒸發量引發對流產生降水，必須先讓溫度升高後增加蒸發量才有機會產生降水，因此在高緯度地區若有降水發生時為溫度越高降水量越多的正相關。除了計算相關係數，本研究計算Precipitation-temperature relationships（PTRs）值，發現在臺灣春季及夏季有明顯負值，表示有降水發生時溫度會明顯下降；而在亞洲季風區內，負值範圍也會隨季節變化，在夏季時會向北擴張。最後使用Frequency of occurrence of precipitation（FOP）及Temperature-precipitation index（TPI）分析方法，由FOP分析可知在臺灣冬季，許多溫度區間下有一半的機率會發生降水，一半不會發生降水，使臺灣冬季降水量與溫度關係不明確；而在夏季則有在相對低（高）溫區間經常發生（不發生）降水的現象。此外，由TPI方法可知臺灣降水大多發生在低於溫度中位數時，僅10～1月期間在部分測站有降水發生在高於溫度中位數時；而在亞洲季風區，降水偏好發生在低（高）於溫度中位數之區域和降水量與溫度之負（正）相關區域相符合。若以天氣系統角度解釋造成不同關係的機制，在夏季影響臺灣及亞洲季風區低緯度地區天氣系統主要為：熱帶低壓、季風低壓、副熱帶高壓等，這些系統帶來（無）降水時，常伴隨氣壓降低（升高）溫度下降（上升）的特性，造成降水量與溫度為明顯負相關；而影響高緯度地區的天氣系統主要為：溫帶氣旋、暖鋒、西伯利亞高壓等，這些系統帶來（無）降水時，常伴隨氣壓降低（升高）溫度上升（下降）的特性，造成降水量與溫度為正相關；而影響臺灣冬季天氣系統較複雜，有濕冷、乾冷、暖乾等不同現象，導致降水量與溫度之關係不明確。This study used Taiwan station data and global gridded reanalysis data to investigate the relationship between precipitation and temperature. In Taiwan, the results revealed a significant negative correlation between precipitation and temperature in summer, a weaker negative correlation in spring, and an insignificant correlation in autumn and winter. Similar phenomena were observed within the Asian monsoon region. Additionally, across the entire Northern Hemisphere, low (high) latitudes regions show negative (positive) correlations throughout the year. Then we added the wind field data to analyze the seasonal changes in the relationship between precipitation and temperature. It was found that within the Asian monsoon region, when there was a northerly component wind, precipitation and temperature exhibited a positive correlation, specifically during autumn and winter, while there was a southerly component wind, precipitation and temperature exhibited a negative correlation, specifically during spring and summer. This imply that the changing variations are related to monsoon and seasonal transition.To further analyze the mechanisms underlying the relationship between precipitation and temperature, this study incorporated Outgoing Longwave Radiation (OLR) and sea-level pressure data. It was speculated that the negative correlation observed in low-latitude regions was primarily influenced by the precipitation type. In summer, when precipitation occurred, cloud cover blocked sunlight and caused a decrease in temperature. Therefore, there was a negative correlation between precipitation and temperature, indicating that higher precipitation resulted in lower temperatures. The positive correlation observed in high-latitude regions may be attributed to the low temperatures, which prevent sufficient moisture and substantial evaporation necessary for precipitation. In such regions, precipitation can occur only when temperatures rise, leading to a positive correlation between precipitation and temperature.In addition to calculating correlation coefficients, this study calculated Precipitation-temperature relationships (PTRs) values. It found significant negative values in Taiwan during spring and summer, indicating a pronounced decrease in temperature when precipitation occurred. Within the Asian monsoon region, the range of negative values varied with the seasons, expanding northward during summer. Finally, using the Frequency of occurrence of precipitation (FOP) and Temperature-precipitation index (TPI) analysis methods, it was determined that in Taiwan during winter, there was a 50% probability of precipitation occurring within various temperature ranges, making the relationship between precipitation and temperature unclear. In summer, precipitation almost exclusively occurred (did not occur) within relatively low (high) temperature ranges. Additionally, based on the TPI method, it was observed that in Taiwan, most precipitation occurred at temperatures below the median, with some stations experiencing precipitation at temperatures above the median only between October and January. This pattern aligned with the negative (positive) correlation between precipitation preference and temperature in the Asian monsoon region.From the weather system perspective, different mechanisms causing these relationships can be explained. In summer, the weather systems influencing Taiwan and low latitude regions mainly include tropical lows, monsoon lows, and subtropical highs. When these systems bring precipitation (no precipitation), they are often accompanied by a decrease (increase) in atmospheric pressure and a decrease (increase) in temperature. This characteristic results in a significant negative correlation between precipitation and temperature. On the other hand, weather systems affecting high-latitude regions primarily include extratropical cyclones, warm fronts, and the Siberian high. When these systems cause precipitation (no precipitation), they often lead to a decrease (increase) in atmospheric pressure and an increase (decrease) in temperature. This characteristic gives rise to a positive correlation between precipitation and temperature. The weather systems influencing Taiwan during winter are more complex, involving phenomena such as cold and wet, cold and dry, and warm and dry conditions, which contribute to the unclear relationship between precipitation and temperature.降水量溫度臺灣亞洲季風PrecipitationTemperatureTaiwanAsian monsoonetd