苏州下垫面格局演变及其局地热环境效应

Change of Underlying Surface Pattern and Its Local Thermal Environment Effect in Suzhou City

以苏州为研究区域,选择1986年Landsat TM、2006年Landsat ETM+遥感图像为主要数据源,分别提取下垫面类型和地表温度,研究景观格局指数的粒度效应,并在适宜粒度下分析景观格局的演变特征,进而研究其与热环境变化之间的关系。结果表明,研究区20多年来景观破碎化程度、斑块形状复杂程度与景观多样性变大,而聚集程度变低,热场变异指数增大区域的景观格局指数变化更为明显,这说明下垫面格局演变对热环境变化具有一定的影响作用。

One of the significant environmental consequences of urbanization is the urban heat island （UHI）, which is associated with underlying land surface types and land use patterns. Selecting Landsat Thematic Map- per （TM） and Enhanced Thematic Mapper Plus （ETM＋） data of Suzhou City obtained on 1986 and 2006 sepa- rately, the paper used the maximum likelihood classification method to extract underlying surface types based on raw visual and near infrared bands, normalized difference vegetation index （NDVI）, modified normalized difference water index （MNDWI） and digital elevation model （DEM） data. Then landscape pattern indices changed with different grain sizes were discussed and its variation characteristics were analyzed within the op- timum grain size. Furthermore, land surface temperature （LST） was retrieved from thermal infrared bands by an emissivity-modified model and then it was used to get distribution of thermal field variance indices. Lastly the paper discussed the relationship between changes of landscape pattern indices and variation of thermal en- vironment. Research results show that landscape pattern indices depend on grain size clearly, the most appropri- ate spatial grain size is from 120 m to 150 m. There is an evident development of the UHI, combined with year 1986, thermal field variance index increase in 2006 as a whole. Fragmentation degree, the shape complexity of the patches and landscape diversity increase while the clustering degree decrease, and furthermore the land- scape pattern indices change more clearly in regions where the thermal field variance indices increase, which indicate that change of underlying surface pattern has an effect on local thermal environment.