2015年冬季苏州城市热岛特征研究

基于Landsat土地利用类型分类资料、夜间灯光影像资料、自动气象站资料以及大气边界层探测资料，划分出城市、郊区以及湖区代表站，分析了苏州2015年1月城市热岛日变化、昼夜差异特征以及城、湖温度差日变化特征，并对苏州城市热岛分布特征以及城、湖大气边界层结构差异进行分析。结果显示：(1)白天热岛强度小，09~17时热岛强度均小于1℃，最小值仅为02℃；夜间热岛强度大，19~05时热岛强度维持在12℃以上，最大值为17℃。(2)城、湖温差白天为正，夜间为负，市区变温速率比湖区快约02℃/h。(3) 苏州白天热中心形状不规则，范围大，城郊温差小，夜间形成单一封闭稳定热中心，热中心形状与市区有较好对应，城、郊温差维持在15℃左右。冬季地面盛行西北风，太湖湖陆风现象显著，湖陆风和盛行风向共同影响城市热羽向西南方向发展。（4）城、湖虚位温廓线在白天差异小，均有不稳定边界层形成，夜间市区仍维持不稳定边界层，而湖区有稳定边界层发展，近地层内干岛效应显著。(5)城市热岛影响范围有明显日变化特征，白天城市热岛影响范围小于40 m，夜间大于200 m。

Research on the Characteristics of Urban Heat Island Effect in Suzhou in the Winter of 2015

Based on the classification data of land use pattern from Landsat, night time light image data, automatic meteorological stations data and atmospheric boundary layer (ABL) sounding data, the representative stations of urban area, rural area, and lake were chosen for the urban heat island (UHI) analysis. The characteristics of UHI in Suzhou in January 2015 were studied in this paper. The result showed that: (1) UHI intensity was weak at daytime, which was less than 10℃ from 09 am. to 05 pm., with the minimum of only 02℃. UHI intensity was strong at night, which maintained above 12℃, with the maximum of 17℃. (2) The temperature difference between urban area and lake was positive at daytime and negative at night. Temperature variation rate of urban stations was about 02℃/h faster than that of lake stations. (3) The shape of heat center was irregular and has a large range at daytime, and the temperature difference between urban and rural area was small in Suzhou. However, at night the temperature difference between urban and rural area maintained at about 15℃,and a single, closed and stable heat center was formed, which was in correspondence with that in downtown area. The northwest wind was prevalent on the ground in winter, and Taihu lake land wind was obvious in Suzhou. The combined action of lake land wind and prevailing wind jointly transferred the urban thermal plume to the southwest. (4) The difference of virtual potential temperature profiles between urban and lake was small, and unstable ABL developed both in urban and lake area at daytime. However, at night, unstable ABL profiles were still maintained in urban area, and stable ABL profiles developed in lake area. In the meantime, the phenomenon of wet island near ground surface was obvious. (5) The influence of UHI in vertical direction has significant diurnal variation, which was less than 40m at daytime, and more than 200m at night.