都市內部氣溫現象之探究

都市熱島效應是指都市中心的溫度高於其外圍鄰近地區之現象，主要是因為都市擴張引發地表形態改變，尤其是大量的不透水鋪面和水泥建築占據市中心而衍生形成。近年關於台灣地區的熱島效應研究，雖然已從氣象觀測資料取得不少分析成果，但對於都市內的高低溫差之整體分布態勢仍缺乏瞭解。因此運用高解析度遙測影像進行都市內部熱島效應分析，遂成為當前值得關注的探究焦點。本研究選擇Landsat-7熱紅外影像作為觀測資料來源，並針對雲遮和缺值問題進行預處理後，推估台北市區在2008年至2014年的夏季地表溫度數值圖。接著分別以大尺度全區範圍和小尺度街區單元，逐年檢視熱島溫度的詳細變化狀況。從分析結果發現在大尺度全區範圍內，熱島高溫長期集中在市區的西半部，而東半部則呈現相對低溫的分布狀況。此外高溫好發地點位在密集型住宅和戶外運動場，反之低溫地點則位在公園綠地和行道樹綠廊附近。至於在檢視小尺度局部範圍時，若以主要幹道圍繞形成的街區為空間單元，則發現溫度值呈現隨內縮而逐漸向街區中心增溫的現象。根據歷年觀測資料進行內縮距離與增溫倍率的相關分析檢驗，結果共有14個街區(約占全體10%)是連續七年存在顯著線性正向關係。另外亦將兩種尺度的長期熱島溫度分析成果，綜合整理為熱島風險型態並探討可行的對應策略。總結本研究提出在台北市區內部全區和街區尺度之熱島分布情況，並為後續研究提供初步成果。

關鍵字

都市熱島效應；熱紅外遙測影像；地表溫度；街區；環域分析

並列摘要

An urban-heat-island effect refers to the pattern of higher land surface temperature in the urban area than its surrounding region. Previous studies attribute the primary cause to rising percentage of the built-up environment which were comprised mainly of impervious pavement and concrete facilities in the downtown. Although stationary records have contributed to plenty analysis in Taiwan over the last half-century, precise status of land surface temperature on the entire city remains scant. Therefore, research nowadays gains focus on uneven distribution of warm and cool temperature within the city since the remote sensing satellites had refined on spatial resolution outstandingly in recent decades. Thus, this thesis aims to conduct an exploratory investigation into the urban-heat-island effect on both downtown-wide and block-wise scale in Taipei via Landsat 7 opening data. Thermal images were selected in consideration of clear weather on either a date in August or any closest date to August of each year from 2008 to 2014. And the land surface temperature was retrieved after being processed by cloudy masking and spatial interpolation. According to outcomes, the western part of downtown was much warmer than the eastern part based on the difference by average temperature. And the cooler places were located in green space such as parks and street trees while the warmers located in compact communities and track in contrast. Besides, preliminary results revealed that there might exist a phenomenon in which the higher temperature occurred at the center of superblock bounded by arterial. With examinations of buffering analysis and Pearson's correlation, fourteen superblocks showed the significantly strong relationship between inward distance and rising ratio of temperature. In addition, all superblocks were given feasible suggestion to reduce the urban-heat-island risk on the basis of thermal situation it's facing. This thesis summarily discovers the pattern of temperature in both coarse and fine scale. Hence, further research needs to be undertaken in the future.

並列關鍵字

urban-heat-island effect ； thermal images ； land surface temperature ； superblock ； buffer analysis

參考文獻

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都市內部氣溫現象之探究

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