基于landsat8 oli数据的合肥市热岛时空特征分析

热岛效应是一种城市化进程中所产生的特有环境问题,是一个地区的气温高于周围地区的现象。为了揭示快速城市化地区热岛的时空变化特点,利用2014年的Landsat8 oli遥感数据,通过遥感算法反演合肥市地表温度,并对合肥市热岛分布及成因加以分析,同时分析了归一化植被指数(NDVI)、归一化建筑指数(NDBI)与热岛分布的关系,以及城市下垫面对热岛效应的影响,并对城市热场进行生态评价分析。结果表明,合肥市四季均存在热岛现象,热岛强度表现为夏季最强,最高温度达57.86℃,秋季次之,春季、冬季较弱。春、夏、秋3个季节热岛多集中在主城区,冬季热岛多分布在乡镇及裸土区,城区热岛强度较弱。热岛效应多集中在不透水面和裸土区,城市冷岛多出现在水体位置。城市热岛分布与归一化植被指数呈负相关关系,与归一化建筑指数呈正相关关系。改进半径法可以较好区分城市建成区,建成区与郊区温度分布存在明显差异。

Landsat8 oli data-based analysis of spatial-temporal characteristics of heat island in Hefei

Heat island defined as the temperature in a specific area is higher than the surrounding area is a peculiar environmental problem resulted from human civilization and development.To reveal the spatial temporal changes of the urban heat island in rapidly urbanizing areas,this study used oli data of landsat-8 in 2014 to retrieve surface temperature in Hefei using remote sensing algorithms.The distribution of heat island and its causes and the relationship between normalized difference building index,normalized difference vegetation index and heat island distribution,as well as the impact to heat island effect by urban underlying surface were analyzed.In addition,an ecological evaluation of the urban thermal field was conducted.The results showed that the heat island effect existed in Hefei year-around.The intensity of heat island effect was the strongest in summer with the highest temperature of about 57.86℃ and the weakest in spring and winter.Heat island areas were concentrated in villages,towns and bare areas in winter and in main urban areas in other seasons with a weak intensity.The heat island effect mainly appeared in impervious surface and bare areas,while the urban cold island appeared near water bodies.The urban heat island distribution had a negative correlation with the normalized difference vegetation index and had a positive correlation with the normalized difference building index.Improved radius method could better distinguish the urban built-up area.There was a significant difference between the built-up area and suburbs.