基于LandsatTM/ETM+的张掖市甘州区绿洲冷岛效应时空变化研究

Temporal and spatial variation of oasis cold island effect in Ganzhou district of Zhangye based on landsat TM /ETM+

绿洲是一种特殊的自然景观,冷岛效应是绿洲独特的现象之一,研究冷岛效应有助于了解绿洲的特征和作用。文中利用2001、2005、2010三个年份的LandsatTM和ETM+遥感影像,运用遥感技术定量分析了甘肃省张掖市甘州区近10年的冷岛效应。(1)定量分析发现:2001年绿洲区比非绿洲区低1.6℃;2005年绿洲区比非绿洲区低1.2℃;2010年绿洲区比非绿洲区低4.9℃。表明张掖市甘州区表现出明显的"冷岛效应"。(2)利用归一化地表温度指数分析发现,白天绿洲区温度低于非绿洲区,体现冷岛效应温度区的面积增加而体现热岛效应区的面积减少,说明冷岛效应的幅度有增强趋势。(3)冷岛比例指数表明张掖市近10年的冷岛效应具有∪变化趋势;(4)地表温度与NDVI的关系分析表明,地表温度与NDVI呈负相关关系,这是绿洲具有冷岛效率的主要原因。

Oasis is a special type of natural landscape. Cold island effect is a unique phenomenon in oasis. Study cold island effect is helpful to understand the characteristics and role of oasis. This research used remote sensing data of 2001,2005and 2010 to quantitatively analyze the cold island effect in Zhangye city, Gansu Province. The results showed： （1）Using normalized difference surface temperature index （ NDSTI ） analysis we found that oasis has lower temperature compared with non -oasis; the temperature area that showed cool island effect was increasing but the temperature area that showed heat island was reducing. Quantitative analysis showed that the temperature in oasis was 1.6℃ lower than that in non - oasis area in 2001, lower 1.2℃ than non - oasis area in 2005, lower 4.9℃ than non - oasis area in 2010. It performed ＂cool island effect＂ clearly. （2） Cold island ratio index shows that cold island effect had a U shaped trend in the Zhangye city in past 10 years. （3） A-nalysis on the relationship between the surface temperature and NDVI showed a negative correlation. Increasing vegetation can alleviate oasis temperature. It provides a theoretical basis for the government to protect the oasis ecological environment.