为掌握银川市城区热环境及其影响因素的时空变化特征,以4期Landsat遥感数据为基础,反演地表温度,采用热岛比例指数、贡献度指数和像元二分模型分析28 a间区域热环境、土地利用和植被的空间分布及其时空演变特征,探讨了地表温度变化及其影响因素的响应关系。研究表明:(1)28 a间,城市热岛比例指数(URI)整体呈上升趋势,热环境呈现出西部地表温度整体高于东部的特征,热岛区域逐渐集中分布于城市建成区。(2)研究区明显升温面积占比为7.38%,而明显降温区域比例仅为1.47%,总体上热环境呈升温趋势。(3)4个年份的未利用土地和草地面积逐年减少,而城乡工矿居民用地面积逐年增加且保持较高增长速度,耕地、水域、城乡工矿居民用地和未利用土地对城区热环境贡献较大。(4)植被覆盖度表现出东部相对较高、西部较低的特点,28年间研究区植被覆盖度较高且整体呈现减小趋势,4个年份的地表温度与植被覆盖度呈负相关关系。银川市城区热环境变化与土地利用类型和植被覆盖度关系密切,各土地利用类型对热环境贡献度表现出差异性,植被覆盖度与其呈负相关。
In order to well know the temporal and spatial characteristics of the thermal environment and its influencing factors in Yinchuan City, land surface temperature(LST)of study area of 4 years were retrieved by using Landsat remote sensing data of 4 periods in 28 years(1989—2017). The spatial distribution and the space-time evolution characteristics of variation of thermal environment, land use and vegetation coverage were studied by employing urban-heat-island Ratio index(URI), contribution index and dimidiate pixel model. Then the response relationship between LULC, vegetation changes for different periods and LST was discussed. The results showed that:(1)URI had increased by 0.138, which tended to be on the rise; meanwhile, thermal environment of 4 years showed that the spatial distribution characteristics that LST in the west of study area was higher than that in the east as a whole and the heat island area concentrated in urban built-up areas gradually because of rapid urbanization;(2)the significantly warming area accounted for 7.38% of total area, however the significantly cooling area just accounted for 1.47%, the thermal environment presented the warming trend on the whole;(3)the areas of unused land and grassland decreased year by year, and built-up land increased gradually with a high growth rate; Among 6 types of land uses, farmland, water, built-up land and unused land presented the major contribution to thermal environment;(4)the vegetation coverage of study area took on the features of relative high vegetation coverage in the east and low in the west, which was at the high level generally and presented a tendency of degeneration as a whole; LST showed the negative correlation with vegetation coverage in 4 periods. The thermal environment of Yinchuan had close relationship with LUCC and vegetation coverage, and the types of LUCC showed the significant differences of the correlations to the thermal environment contribution, while vegetation coverage had negative correlation with LST.
