基于MODIS数据的拉萨市地表温度变化研究

Changes of Spatial Distribution of Land Surface Temperature in Lhasa

采用2000～2011年6月MODIS地表温度产品和拉萨市4个气象站6月平均地表温度对拉萨市地表温度的时空变化进行了分析.结果表明：拉萨市在近12年内地表温度呈明显上升趋势,2009年地表温度达到最高为28.49℃,最小值出现在2003年为14.12℃.在空间分布上高温区主要集中在城市中心和城市周边区域,并随着时间推移不断向外扩张,在2007年6月拉萨市地表温度高温区分布范围最大,其中纳木错东部和林周县的高温区增加最显著;在利用实测的地表温度与MO-DIS反演的地表温度做相关分析发现,两者的相关系数为0.64通过了0.001的显著性检验,两种地表温度的时间变化趋势也较为一致,因此MODIS地表温度反演产品适用于大范围地表温度和城市热环境监测是可行的.

Based on the historical data recorded at the meteorological stations of Lhasa City, Meldro Gungkar County and Nyemo County, together with those collected at 8 recently established automatic meteorological stations in Lhasa city, the variations and trends of the urban heat island （UHI） effect in Lhasa City are analyzed, and the possible impact factors on UHI effect in Lhasa City are discussed. It shows that the UHI effect in Lhasa City has a significant increasing trend from 1978 to 2011, with an average value of 0. 24℃ per decade. On average, the highest intensity of UHI effect appears in winter （2.0℃） , followed by that in spring （ 1.8 ℃）, autumn （ 1.7℃ ）, and summer （ 1.6℃ ）. It appears that the central of high temperature is mainly at the center of the city, and the temperature declines from high - level area to its flanks. Temperatures in rural areas are relatively Dower than that in urban areas with a mean difference of 0. 9℃. Moreover, nocturnal heat island intensity was sig- nificantly higher than that during the day. With growing urbanization, a large change of surface land conditions, a growing number of city buildings, the surge of human activities and energy consumption, are responsible of resulting in growing UHI effect in the Lhasa City.