地表温度扰动特性及其与建设用地扩张的关系

河口地区是人口密集、经济繁荣的区域之一,同时也是生态环境脆弱区,易受到人类活动带来的负面影响,其中热环境恶化问题尤其突出。本文基于多源遥感影像数据,结合遥感技术和统计学方法,研究城市化进程中闽江河口地区20年来的地表温度变化特性;利用Moran's I指数分析研究区表面温度的空间集聚特性及其产生的尺度效应,并定量分析表面温度与不同景观类型的相关性。结果表明：① 1993-2013年,闽江河口地区建设用地面积大幅增加,经历了由慢至快,而后稳中有升的过程;城市扩张是通过大量大规模的边缘式扩张实现的,东部、西部和南部是扩张的3个主要方向。② 地表温度空间格局变化明显,次高温区和高温区显著增加,次低温区和中温区减少,低温区变化不大;高温区扩散方向与建设用地扩张方向基本一致。③ 地表温度存在明显的扰动现象,表现为靠近主城区剧烈,城郊和郊区相对和缓的特性,同时地表温度空间格局具有显著的空间聚集性。④ 建设用地扩张是地表温度增强的重要原因,林/草地和水域能有效缓解区域高温;耕地并未表现出显著的降温效果,但随着耕地比重的增加,地表温度逐渐趋于稳定。研究结果可为改善城市热环境、促进区域可持续发展提供有益参考。

Characteristics of Land Surface Temperature Disturbance and Its Relationship to Built-up Land Expansion

Estuarine region is one of the most densely populated and prosperous area around the world, and it is also an eco-environmental vulnerable area which is more fragile to human activities. The acceleration of urbanization have inevitably resulted in a series of ecological and environmental problems on estuarine region, the thermal environment is a severe part of them. Higher temperatures and extreme heat not only hamper air quality but also increase energy consumption for cooling, threatening the health of urban residents. Based on the multi-source remote sensing images, characteristics of land surface temperature under the urbanization in Minjiang River estuary area were analyzed by using remote sensing techniques and statistical methods. With the help of Moran's I index, spatial clustering characteristic and scale effect of LST were examined. Further, the correlations between LST and different landscapes were found in quantitative analysis. The results showed that: (1) Built-up land area increased sharply from 1993 to 2013, showing a slow-rapid-steady and increasing process. A large number of large-scale edge-expansion was the primary growth type, meanwhile urban sprawl was mainly in east, west and south directions. (2) The area of sub-high and high temperature zone increased markedly, while the sub-low and middle temperature zone reduced; and there was no significant change in low temperature zone. Moreover, the spatial distribution of the high temperature region was consistent with built-up land expansion. (3) The LST exhibited an obvious disturbance characteristic; the temperature near city center presented dramatic changes and the temperature fluctuation in suburb was relatively smoother than Fuzhou city proper. On the other hand, the LST had a significant spatial clustering characteristic, and the spatial pattern of LST had a scale effect. (4) The dominance of built-up land significantly strengthened surface temperature, while increasing the dominance of vegetation and water could cool temperature. Cropland displayed no sign of cooling effect, the LST tended to be stable as the percentage of cropland increased. The results of the study can provide a useful reference for improving urban thermal environment and developing sustainable cities in estuarine regions.