Thermal environment effect of land surface water bodies in Beijing based on satellite data

Abstract

应用不同分辨率的卫星资料对北京水体类别、密云水库及城区典型水体的热环境特性及城区水体对其周围热环境影响进行研究分析.利用2006年的MODIS卫星地表温度产品对北京不同类型的地表温度研究显示:就北京四季平均状态来说,水体类别在白天具有降温作用,在秋季和冬季夜晚具有保温作用,在春季和夏季夜晚具有降温作用.利用NOAA/AVHRR卫星资料对密云水库的研究分析显示:密云水库在夏季白天具有冷湖效应,夜晚具有暖湖效应;密云水库在冬季未结冰时白天和夜间具有暖湖效应,在结冰时白天具有冷湖效应而晚上无冷暖效应.利用FY-3A/MERSI、NOAA/AVHRR和Landsat-TM卫星资料对北京城区典型水体监测结果显示:城区水体不会有热岛现象出现,大面积的水体易出现冷岛效应.利用2008年夏季Landsat-TM卫星资料对城区典型水体和天坛公园绿地500 m范围内的建筑地温研究分析显示:城区水体温度明显低于天坛公园绿地.城区各水体周边100 m范围内建筑区地温平均下降1.2℃;100~200 m内下降0.6℃;200~300 m内下降0.4℃,300 m范围外无明显变化.天坛公园绿地周边仅100 m内的建筑区地温下降,下降值为0.4℃.这些研究结果表明:卫星资料能有效监测水体的热环境效应,大面积的水体是降低城市地表热岛效应的重要来源,北京城区水体对周边最大300 m范围内的建筑区地表温度具有降温效应.;Satellite data in different resolutions were used to study thermal environment characters of water body type,Miyun Reservoir, typical urban water bodies and their impacts on the environment around Beijing.The research of different land-use types using MODIS land surface temperature product indicated that at average seasonal time scale water body type of Beijing had temperature-decreasing effect during the daytime,while it had temperature-increasing effect in the night,of autumn and winter,and had temperature-decreasing effect in the night of spring and summer.The analysis of Miyun reservoir using NOAA/AVHRR data showed that it had cold lake effect in the daytime and warm lake effect in the night in summer.On no-freezing condition in winter, Miyun Reservoir had warm lake effect during the day and night.But on freezing condition it had cold lake effect during the day and had no warm or cold island effect during the night.The monitoring results of typical urban water bodies in Beijing using FY-3A/ MERSI,NOAA/AVHRR and Landsat-TM data indicated that water bodies of urban had no heat island effect and the larger area water bodies had strong cold island effect.The analysis of land surface temperature of buildings within 500 meters to typical urban water bodies and Temple of Heaven Park,respectively,indicated that water bodies had lower temperature than the green space of Temple of Heaven Park.Average ground surface temperature of buildings decrease by 1.2,0.6 and 0.4℃ with the distance away from water bodies less than 100 m,100-200 m and 200-300 m,respectively.Green space of Temple of Heaven Park had cooling effect only within 100 m distance with the surface temperature decreased by 0.4℃.The results showed that satellite data could be effectively used to monitor thermal environment of these water bodies,and large area of water bodies were important sources of slowing down urban heat island effect.The maximum distance of cooling effect of water bodies on building around was 300 m in the urban areas of Beijing.