基于单窗算法的汉中市近20年城市热岛效应时空特征

以1994年、2000年、2004年、2009年和2015年5期Landsat TM遥感影像为主要数据，采用单窗算法反演汉中市地表温度，并对地表温度进行归一化处理得到汉中市热岛强度分级图，分析汉中市近20 a热岛效应时空变化特征及其与土地利用类型、植被覆盖度之间的关系。结果表明:1）近20 a汉中市城市热岛效应随时间变化呈“先升后降”的变化趋势，1994-2004年为热岛效应的加速期，2004-2015年为减缓期。2）不同热岛强度的空间分布特征差异明显。1994-2005年强绿岛区和绿岛区主要分布在汉中市北部的山林地区；强热岛区和热岛区主要分布在西南部的中心城区。3）不同热岛强度对应的不同土地利用类型存在差异。强绿岛区和绿岛区主要分布在汉中市北部山区的林地和耕地。正常区主要集中在汉中市近郊的农用地与草地，同时也包含市区周边的零散村镇居民地。热岛区和强热岛区主要分布在中心城区的建筑用地。4）植被覆盖度与城市地表温度呈显著负相关关系，植被覆盖度每增加10%，地表温度平均下降约1.1℃。可见，增加城市植被覆盖度，合理利用城市裸地和布局城市建筑用地，可以缓解城市热岛效应。

Spatial-Temporal Characteristics of Urban Heat Island Effect in Hanzhong City in Recent 20 Years Based on Mono-window Algorithm

Based on Landsat5 TM remote sensing images of Hanzhong in 1994-2015,using mono-window algorithm to invert the surface temperature,the classification of heat island intensity was obtained by normalization of surface temperature.This paper analyzed the spatial and temporal variation characteristics of nearly 20 years heat island effect in Hanzhong and its relationship between heat island effect and land use type and vegetation coverage.The results shown that 1)in recent 20 years,the urban heat island effect of Hanzhong presented the tendency of "first rise and then fall" with time.It was intensified in 1994-2004,slowing down in 2004-2015.2) The spatial distribution characteristics of different heat island intensity were obvious.In 1994-2005,the strong green island and green island areas were mainly distributed in the northern areas.The strong heat island and heat island areas were mainly distributed in the central area of the southwest.3) There were different land use types for different thermal island intensity.The strong green island and green island areas were mainly distributed in woodland and arable land in the northern mountainous area,the normal area mainly focused on the agricultural land and grassland in the suburbs,also including the scattered villages and towns around the city.The strong heat island and heat island areas were mainly distributed in the building land of central urban.4) Vegetation coverage was significant negatively correlated with urban land surface temperature.With the vegetation coverage increased 10%,the average surface temperature fell about 1.1℃.Therefore,increasing urban vegetation coverage,reasonable using urban open land,and the reasonable layout of urban construction land could alleviate the urban heat island effect.