乌鲁木齐城市地表温度时空变化与贡献度研究

伴随着新疆首府乌鲁木齐市经济快速发展,人口持续增加、城市化进程不断加快,地表温度也发生极其显著的变化。以乌鲁木齐市中心城区为研究对象,利用1990—2018年的4期Landsat卫星影像和中国科学院土地利用/覆被分类数据,采用地表温度反演、重心转移模型、空间聚类分析以及计算贡献度指数等方法,定量研究乌鲁木齐市城市化进程中地表温度的时空格局变化及土地利用/覆盖对热环境的贡献程度。结果表明,(1)1990—2018年间,研究区相对地表温度等级在<0、0—2、>8等级上面积增加,2—4、4—6、6—8等级上面积减少。面积增长最大的是<0的相对地表温度等级,面积减少最多的是6—8等级,从空间分布上看,温度区分布有从中间向外围递增的现象。(2)1990—2018年间,研究区内相对地表温度等级在0—2、2—4、4—6区域的重心均表现为先向东南,再向西,再向东北转移的趋势,相对地表温度等级>8区域的重心先向西南,再向东北转移,相对地表温度等级<0的区域温度重心一直北移,空间上呈现等级越高越靠东的现象,相对地表温度等级<0分布在中间,相对地表温度等级>8区域的重心转移距离最长,相对地表温度等级在0—2区域的重心转移距离最短。(3)研究区内的LST在空间上呈现出很强的集聚效应,从整体上均表现为等级越高集聚性越强的现象;1990—2018年间,区域热岛的集聚程度在不断降低,空间尺度临界值逐年下降。(4)1990—2018年间,研究区建设用地与水域面积增加,其余类型均在减少,面积增长最大的为建设用地,面积减少最大的耕地面积。各土地利用/覆盖类型的贡献度指数从大到小表现为草地、建设用地、未利用地、林地、水域、耕地,其中草地、建设用地、未利用地为正贡献,林地、水域、耕地为负贡献。贡献度值指数大小与面积密切相关。

Spatial-temporal Patterns of Land Surface Temperature and Contribution in Urumqi,China

With the rapid economic development of Urumqi,the capital of Xinjiang,the population continues to increase,the urbanization process is accelerating,and the surface temperature has also changed significantly.Taking Urumqi central urban area as the research object,this paper uses the four phases of Landsat satellite imageries from 1990 to 2018 and land use/cover classification data of Chinese Academy of Sciences.The temporal and spatial pattern changes of land surface temperature and the contribution degree of land use/cover to thermal environment in Urumqi during urbanization were quantitatively studied by using land surface temperature inversion,center of gravity transfer model,spatial cluster analysis and contribution index calculation.The results show that:(1)The area of relative surface temperature classes in the study area increased in<0,0?2 and>8 grades,while the area of 2?4,4?6 and 6?8 decreased from 1990 to 2018.The largest increase in area is the relative surface temperature level of<0,and the largest area reduction is 6?8 grade.From the spatial distribution,the temperature distribution increases from the middle to the outside;(2)The center of gravity of the region with relative surface temperature grade of 0?2,2?4 and 4?6 in the study area showed a trend of first southeast,then West,and then northeast.The center of gravity of the area with relative surface temperature grade>8 first moved to the southwest and then to the northeast.The center of gravity of the region with relative surface temperature grade<0 moved northward and the higher the grade,the more east it was.The results show that the relative surface temperature level<0 is distributed in the middle,the center of gravity transfer distance is the longest in the relative surface temperature level>8,and the shortest in the area of relative surface temperature level 0?2 from 1990 to 2018;(3)The results show that LST in the study area has a strong agglomeration effect in space,which shows that the higher the level,the stronger the agglomeration;And(4)the area of construction land and water area in the study area increased,while the other types decreased from 1990 to 2018.The largest area growth was construction land,and the area of cultivated land decreased the most.Grassland,construction land,unused land,forest land,water area and cultivated land were the main contribution index of each land use/cover type from large to small.Grassland,construction land and unused land were positive contribution,while forest land,water area and cultivated land were negative contribution.The contribution index is closely related to the area.