摘要
城市化在给人类社会带来进步的同时也给城市带来一系列环境问题,城市热岛效应是城市化进程带来的较明显的副产品。文中用1990、2000和2002年LandsatTM/ETM+遥感影像研究城市植被覆盖变化对城市热岛的影响,研究区选广州市中部七区。首先对遥感影像进行精几何校正,用支持向量机对影像进行分类并计算出各区植被覆盖率。其次,用Landsat波段6反演地表亮温,计算出各区平均亮温值并转换为符合正态分布的亮温偏移值;最后对各区不同年份的植被覆盖率和亮温偏移值的关系进行研究。比较研究区3年内植被覆盖率发现,由于城市的快速发展,1990年到2000年植被覆盖率减少了7%,而2000年到2002年植被覆盖率增加了3%,区亮温偏移值与植被覆盖率呈负相关,相关系数为-0.86;比较各区不同年份亮温偏移值可以发现,越秀区的亮温偏移值在1990和2000年均高于各区,但在2002年由于该区近两年内植被覆盖率的增加而有所降低。2002年除萝岗区和白云区外,其它5区的亮温偏移值较接近,说明2002年各区的热岛强度得到有效控制。
Urbanization makes progress in human society, at the same time it brings a series of environmental issues to city. The urban heat island effect is one of the obvious byproducts brought by urbanization. In this paper, the effect of vegetation cover change on urban heat island is investigated using three Landsat TM/ETM＋ images acquired in 1990, 2000 and 2002. The study area is located at the centre seven districts of Guangzhou city, in China. Firstly, the images were geometric precision correction and classified using Support Vector Machine （SVM）, and then every district vegetation cover ratio was computed out. Secondly, brightness temperature was retrieved by band 6, and the brightness temperature mean of every district was computed out and converted into the deviation value which belonged to normal distribution. Finally, the relationship between vegetation cover ratio and the brightness temperature deviation value in different years was investigated. Comparing three years vegetation cover ratio of study areas, it concludes that the vegetation cover ratio was decreased by 7% from 1990 to 2000 due to the city rapidly development, however, it increased 3% from 2000 to 2002. The district brightness temperature deviation mean value was positively correlated with the vegetation cover ratio and the correlation coefficient is -0.86. Comparing districts brightness temperature deviation mean value in different years, the brightness temperature deviation mean value of Yuexiu District is the highest in 1990. However, it decreased in 2002 due to the vegetation cover ratio increase in the last two years. In 2002, all districts have the near brightness temperature deviation mean value except Luogang and Baiyun, so the difference of heat island intensity between districts is not significant.
出处
《生态环境》
CSCD
北大核心
2008年第3期985-988,共4页
Ecology and Environmnet
基金
国土资源大调查基金项目资助(2003024002)
关键词
植被覆盖率
亮温
城市热岛
LANDSAT
ETM+
广州
vegetation cover ratio
brightness temperature, urban heat island
Landsat ETM＋
Guangzhou
