以Landsat衛星數據解析土地利用差異下植被覆蓋率對都市熱島之影響

Responses to Fractional Vegetation Cover in Relation to Urban Heat Island in Different Land Uses Using Landsat Data

增加綠化植被得以降低城市熱島（UHI）溫度是一種眾所周知的緩解策略。但是，很少有文章提到這種緩解效果的具體效果。植被綠化可以植被覆蓋率（FVC）代替。本研究基於Landsat 8／TM圖像和GIS空間分析技術，從1900年到2018年解析臺北盆地的UHI溫度和FVC，並且定量分析了都市不同土地利用分區的UHI和FVC之間的差異及空間關係。結果顯示UHI和FVC之間存在明顯的負相關變化趨勢。迴歸分析表明，大約超過38％的植被覆蓋率則可以產生降溫效果。從迴歸函數可以推論FVC愈高則緩解UHI的效果愈佳。當FVC增加時，商業區的地表溫度下降最快，反之，自然資源區域的地表溫度下降最慢。再者，人為熱量釋出可能在UHI效應中扮演著重要作用，所以必須考慮減緩UHI效應來系統性的規劃都市綠地之分布。

Greening vegetation cover to reduce urban heat island temperature (UHI) is a well-known mitigation strategy. However, few articles mention this mitigation improvement effect. Greening vegetation coverage measures can be replaced by fractional vegetation cover (FVC). Based on Landsat 8/TM images and GIS spatial analysis techniques, UHI temperatures and fractional vegetation cover (FVC) from 1900 to 2018were obtained for the Taipei basin. The differences and spatial relationships between the UHI and FVC for different land-use zones in the city were quantitatively analyzed. There was an obvious reverse variation trend between the UHI and FVC. Regression analysis showed that a green coverage rate over 38% could produce a cooling effect. It can be inferred from the regression equation that the higher the FVC, the better the mitigation effect on UHI. When it increased FVC, the surface temperature of the commercial area decreased most quickly, and that of the natural resource area decreased most slowly. The results suggest that anthropogenic heat release probably plays a significant role in the UHI effect, and must be considered in mitigating the UHI effect in urban green space system planning.