天山北坡城市群地表温度时空差异及贡献度分析

Analysis of the spatial and temporal differences in surface temperature and the contribution of surface coverage in the urban agglomeration on the northern slope of the Tianshan Mountains

城市化的加快推进使得土地利用变化加剧,进而导致城市热环境问题日益突出。基于2005年和2018年夏季的MYD21A2地表温度数据,运用空间统计学方法分析了LST的时空分布格局,并结合土地利用数据,通过贡献度指数,对天山北坡城市群地表覆盖类型和行政区划的源汇角色特征进行了分析。结果表明:(1)2005—2018年建设用地、耕地增长显著,冰川、林地等自然资源地类显著减少,说明城市的发展对生态环境和自然资源造成了较为严重的影响。(2)地表温度等级的空间分布与海拔呈负相关关系,2005—2018年高温度等级在白天的空间分布有离散化趋势,而夜间则相反,夜间高温度等级空间分布整体有向东南迁移的趋势。(3)不同城市、不同地表覆盖类型由于自然条件、比热容等物理性质的不同,其白天和夜间源汇角色不同,可归纳为昼夜热源型(CI>0)、昼汇夜源型(白天CI<0,夜间CI>0)和昼夜热汇型(CI<0)。(4)天山北坡城市群独特的气候和荒漠—绿洲—山地地貌致使建设用地为昼汇夜源型地类,源汇角色与内地一些城市群(京津冀城市群)存在差异。

The acceleration of urbanization has intensified land use changes,which in turn has led to increasingly prominent urban thermal environmental problems.Based on MYD21A2 surface temperature data from the summers of 2005 and 2018,the spatial and temporal distribution pattern of LST was analyzed using spatial statistics,combined with land use data,and the contribution index was used to determine the source of land cover types and administrative divisions of the urban agglomeration on the northern slope of the Tianshan Mountains.Between 2005 and 2018,construction land,cultivated land increased significantly,and natural resource types,such as glaciers and forest land,decreased significantly,indicating that urban development had a serious impact on the ecological environment and natural resources.The spatial distribution of surface temperature grades is negatively correlated with altitude;from 2005 to 2018,the spatial distribution of high temperature grades in the daytime has a discretization trend,while the opposite is true at night,and the overall spatial distribution of high temperature grades at night has a tendency to migrate to the southeast.Different cities and land cover types had different day/night source and sink roles due to different natural conditions,specific heat capacity,and other physical properties;these can be summarized as a day and night heat source type(CI>0),a day and night sink type(day CI<0,night CI>0),and a day and night heat sink type(CI<0).The unique climate and desert-oasis mountain landforms of the urban agglomeration on the northern slope of the Tianshan Mountains led to a diurnal sink and night source land for construction land,with the role of source and sink being different from that of some inland urban agglomerations(Beijing-Tianjin-Hebei urban agglomeration).