杭州城市热岛的变化趋势

对杭州，萧山，临安近30年的气象资料分析，可看出，杭州和萧山的年平均气温越来越高，而临却有下降的局势，萧山比杭州增温更快，杭州与临安的温差越来越大，其中除7，11，12月份外，其余9个月温差增大比较显著，从调查的1，4，7，8，10有5个月各时段杭州与临安的温差情况看出，7，8月以晚上20时温差显著，1，4，10月以下午4时显著，人工下垫面增加是气温增高的重要因素，良好的生态环境，较高的森林覆盖率，有助于减轻热岛效应。

Variation Tendency of HeatIsland in Hangzhou

Analysis on the meteorolgical data of last thirty years in Hangzhou,Xiaoshan and Lin＇an indicates:the annual average temperature of Hangzhou and Xiaoshan is increasing,but Lin＇an is decreasing.The temperatare of Xiaoshan increases more rapidly than Hangzhou,the temperature difference between Hangzhou and Lin＇an gets more and more distinguished except July,November and December.Refering to the temperature difference of Hangzhou and Lin＇an in January、 April、July、August、October,the difference is the most evident at 8 pm in July and August,but at 2 pm in January、April and October.The increase of artificial building is the main factor causing temperature increase.Better ecological environment and higher forest coverage help to decrease the effect of heat island.