臺灣地區溫濕度指數之分布

臺灣地區位處熱帶與亞熱帶交界處，熱季期間長，濕度較高，造成溫濕度指數（temperature humidity index, THI）亦高。本文以中央氣象局臺灣南區氣象中心網站之長期氣候資料，利用直線迴歸及繪圖軟體，將臺灣南部地區從1976至2005年月平均溫度及年平均溫度，畫成曲線圖及直線迴歸圖；並根據中央氣象局1971至2000年之平均每月最高氣溫及平均氣溫及月平均相對濕度計算成THI值。臺灣低海拔地區熱季之期間相當長，從每年之4月上旬至10月下旬。若以最高溫度計算之THI時，每年有6個月處於中度熱緊迫（79≦THI＜89），2.55個月處於輕度熱緊迫（72≦THI＜79），每年共有8.55個月處於熱緊迫狀態（THI≧72），只有1.09個月為最佳人工授精率（68≦THI）門檻內。若以平均溫度計算之THI時，每年有2.55個月處於中度熱緊迫（79≦THI＜89）狀態，4.18個月處於輕度熱緊迫（72≦THI＜79），每年共有6.73個月處於熱緊迫狀態（THI≧72），只有4個月為最佳人工授精率（68≦THI）門檻內。隨著海拔高度之增加，THI值愈減，對家畜之熱緊迫漸減，在海拔1,000 m之日月潭地區，全年均在THI＜72。但我國之酪農業大部份分布於海拔100 m以下，對熱季溫度日益增加情況下，需加強蒸發降溫系統之研究及耐熱牛隻之選育。

關鍵字

臺灣；溫濕度指數；熱緊迫；乳牛

並列摘要

Taiwan is located between the tropical and subtropical areas, and has a long period of high ambient temperature and relative humidity. Thus high temperature - humidity index (THI) makes livestock suffer from heat stress during the hot season. The historical climate data in this paper were collected from 1976 to 2005 on the website of http://south.cwb.gov.tw/. Graphic software was used to transfer monthly average temperature vs. calendar month to a diagram, and yearly average temperature vs. calendar year to a linear regression. Another climate data from 1971 to 2000 were collected on the website of http://www.cwb.gov.tw/. Temperature-humidity index (THI) was calculated by monthly mean maximum temperature, monthly mean temperature vs. relative humidity. Monthly maximum and mean THI at different altitudes from January to July were compared to the comfortable months for dairy cows. When monthly maximum and monthly average temperature were calculated as parameters in the THI in low altitude area, cows suffered from moderate heat stress (79≦THI＜89) for period of 6 and 2.55 months per year, respectively; from mild heat stress (72≦ THI＜79) for 2.55 and 4.18 months, respectively; and only 1.09 and 4.0 months were within THI threshold good for artificial insemination, respectively. THI was found higher in southern Taiwan, and lower in northern Taiwan. THI decreased with increasing altitude, resulting in less heat stress for livestock. At an altitude as high as 1,000 m in Sun-Moon Lake area, no heat stress (THI＜72) was found as monthly average temperature including in THI in the whole year. However, most of dairy farms are located in lower altitude areas (＜ 100 m), thus cattle suffered from heat stress from April to October. With high ambient temperature during the hot season, evaporative cooling system should be used and more work on genetic selection must be done in the future.

並列關鍵字

Taiwan ； Temperature-humidity index (THI) ； Heat Stress ； Dairy cow

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