台灣海岸型城市之都市熱島現象與改善對策解析－－以台南、高雄及新竹為例

EXPERIMENTAL ANALYSES ON URBAN HEAT ISLAND EFFECT AND ITS IMPROVEMENT STRATEGIES IN COASTAL CITIES OF TAIWAN－ANALYSES FOR TAINAN, KAOSHOUNG AND HSINCHU

本研究藉由都市熱島實測方法，進行台南、高雄與新竹三大城市氣溫分佈圖與都市土地利用的概觀解析，並探討其都市熱島現象的時空分布特性；本論文發現，屬於海岸地形的台南、高雄與新竹，其受到海陸氣候極大的影響，使得白天熱島中心偏向內陸，晚上則偏向海邊；而綠地系統的規模大小，直接影響綠地對於都市氣溫環境的改善效果。最後，由本研究所測得台南的最大熱島強度為4.4°C，高雄為3.4°C，新竹為3.7°C。另外，本研究利用地理資訊系統，進行都市熱島影響因數之解析研究，其結果(1)就台南而言：在中午與晚上時段，每降低10%的建蔽率，約有0.3°C的降溫效果，而午夜時段，每增加10%的綠覆率，可降低氣溫約0.1°C。(2)就高雄而言：中午時段每增加10%的水域密度，約有0.1°C的降溫效果，在晚上時段每平方公里減少1萬人，約有0.2°C的降溫效果，而午夜時段每降低50%的容積率，可降低氣溫約0.3°C。(3)就新竹而言：三個時段降低人口密度效果最大，每平方公里減少1萬人，約有0.7°C、0.8°C、0.8°C的降溫效果。以上分析結果證明，都市土地利用狀況對於都市溫濕度環境具有實質與關鍵性的影響力，由此，本研究提出都市熱島改善對策與最有效之都市計畫手法，其結果對於都市計畫與國土利用規劃之決策參考，將具有實質的貢獻與助益。

The spatial and temporal features of urban heat islands of the metropolitan cities, Tainan, Kaoshoung and Hsinchu in Taiwan are studied by the temperature isotherm maps and the city contexts and textures .The results reveal that the heat island patterns of the coastal cities, Tainan, Kaoshoung and Hsinchu is affected by the sea and land breezes. It is also clear from the results that in urban areas, large greened areas or parks play a key role in reducing temperatures. Finally, the greatest heat island intensities of Tainan, Kaoshoung and Hsinchu found in the evenings, are 4.4°C, 3.4°C and 3.7°C respectively. In addition, data collected from the urban heat island survey of the three metropolises are analyzed with the urban geographical information through the multivariate statistical analysis methods. In summary, results of the survey are: (1)In Tainan, the average air temperature decreases 0.3°C when the building coverage decreases10% at noon and night. the average air temperature decreases 0.1°C when the green coverage increases 10% at midnight. (2)In Kaoshoung, the average air temperature decreases 0.1°C when the water density increases 10% at noon. the average air temperature decreases 0.1 ¢J when the people decreases 10000/km2 at night. the average air temperature decreases 0.3°C when the building volume decreases 10% at midnight. (3)In Hsinchu, the average air temperature decreases 0.7°C, 0.8°C, 0.8°C when the people decreases 10000/km2 at three times. Results of the analyses indicate that urban thermal environment can be improved by proper city plan. Moreover, solutions valuable to city planning to mitigate heat islands are also included.