超大城市热岛研究方法对比:以上海为例

A Comparison Study of Research Methods for Urban Heat Island of Megacity:with Special Regards on Shanghai

在超大城市,热岛往往存在着多中心发展的态势,以上海为例,采用2007年33个气象站点逐日4时刻(2:00,8:00,14:00,20:00)的气温数据,提出了一种新的热岛强度计算方法.新方法考虑站点所在区域下垫面的土地利用类型,将位于已显著城市化的郊区中心区站点计入城区站点进行热岛强度计算.将这一方法的计算统计结果与传统方法进行对比,结果表明:(1)两种方法统计的全年热岛出现频次存在显著差异,而全年热岛累积强度的差异并不明显;(2)对于热岛日变化特征,两种方法统计的热岛出现频次和热岛累积强度分布一致;在14:00时,该方法计算和统计的热岛效应在出现频次和累积强度上均显著高于传统方法,而在2:00时,两种方法的结果差异不大;(3)两种方法在反映热岛出现频次和累积强度的季节变化特征上存在明显差异;在夏季和春季,该方法统计出的热岛效应较传统方法更为显著;(4)进一步分析表明,在太阳辐射较强的时刻和季节,两种方法计算和统计的结果差异较大;该方法可弥补传统方法掩盖的某些热岛特征;(5)以松江为代表的上海郊区存在显著的次级热岛,郊区中心站点气温显著高于郊区非中心站点.在对上海这样的特大型城市进行热岛效应研究时,若将郊区中心地区站点像传统方法一样简单计入郊区站点,则可能难以反映城市次级热岛特征.

The development of international megacity is usually characterized by multi-center.Based on temperature data with four times a day（2：00,8：00,14：00,20：00） provided by 33 stations in 2007,the characters of the UHI（Urban Heat Island） in Shanghai were studied,a new method to calculate UHI was developed.The new method adds the stations located in the center of urbanized suburban into urban stations.The comparison between traditional method and new method shows that：（1） The frequency differences between UHIs calculated by new method and traditional method is significant,while the differences between accumulated UHIs is not significant.（2） About the daily variations,the patterns of UHI frequency and accumulated UHI by two methods are similar;the differences of UHI frequency and accumulated UHI by two methods are significant in 14：00,while in 2：00 the differences are not significant.（3） About the seasonal variations,the results calculated by two methods significantly differs from each other.In summer and spring,the UHI is more significant when calculated by new method.（4） In time and season when the solar radiation is strong,the difference between results calculated by two methods is significant.Using the new method could reveal some characters neglected by traditional method.（5） The secondary UHI in Shanghai is significant.The station located in the center of Songjiang district monitored a significantly higher temperature than other rural stations.It＇s more reasonable to calculate UHI with the method referred in megacity like Shanghai.