基于卫星遥感揭示长三角台站周边城市土地利用扩张及其对气温记录的影响

台站温度记录中的城市化信号对于气候变化研究影响重大并仍存在很大争议，尤其是在经历快速城市化的区域。本研究利用遥感影像分类的方法，提取了1980~2009年期间长江三角洲城市群93个气象台站周边10 km×10 km范围的城市土地利用信息，并按照城市土地利用扩张速率对站点进行分类，研究了1980~2009年期间快速城市化站点、中速城市化站点和慢速城市化站点的年和季节平均温度、最低温度和最高温度变化特征，并分析了快速和中速城市化站点城市化影响和城市化影响贡献率。结果表明:全部93个气象站点周边自20世纪80年代起均经历了城市土地利用扩张过程，全部站点周边的平均城市土地利用扩张速率为1.00% a-1；近30年来，各类型站点年和各季节的平均温度、最低温度和最高温度均表现出增加趋势；城市化效应增强因素对快速城市化站点年平均温度贡献率为35.06%，对年平均最低温度的增温贡献率为34.67%，对年平均最高温度增温贡献率最小，仅为18.42%；城市化效应增强因素对中速城市化站点的影响程度小于快速城市化站点，对平均温度、最低温度和最高温度的贡献率分别为19.35%，22.22%和3.13%。在季节变异方面，长江三角洲区域各类型站点冬季的城市化影响贡献率在平均温度、最低温度和最高温度均表现为最低值。

Satellite Remote Sensing-Based Urban Land-Use Expansion and Its Influence on Surface Air Temperature Records in the Yangtze River Delta, China

It is still controversial how to quantify the contamination of temperature records by urbanization effects on regional scale, especially in regions where urban built-up expands rapidly like China. Based on historical remote sensing data, this study calculates the urban land-use expansion rate at around 93 meteorological stations in the Yangtze River Delta and classifies these stations into three categories. Using air temperature records from basic/reference meteorological stations, annual and seasonal variations of mean, minimum, and maximum temperature characteristics at different types of stations during the periods from 1980 to 2009 were calculated, and further examine urbanization effects and their contributions to temperature changes at stations that have experienced rapid and moderate urbanization. The results show that almost all the 93 meteorological stations have experienced urban expansion with the expansion rate reaching 1% a^{-1 in} the last three decades. Meanwhile, significant increases in annual and seasonal means of minimum and maximum temperature can be detected at different types of stations. In those stations that experienced rapid urbanization, contributions of urbanization effects to annual mean, minimum, and maximum temperature changes reach up to 35.06%, 34.67%, and 18.42%, respectively. Meanwhile, contributions of urbanization effects at moderate urbanization stations account for 19.35%, 22.22%, and 3.13% of the annual mean, minimum, and maximum temperature changes, respectively. The impact of urbanization on the warming trend varies in different seasons, and the minimum warming trends is found in the winter.