Distributive characters of urban heat island effect in Xi'an City

Basing the hourly temperature data of the automation weather station(AWS) and encryption AWS in Xi'an city from 1959-2008,the temperatures between rural area and urban were compared.Results showed that urban heat island(UHI) intensify increased year by year.The diurnal change of urban heat island indicated that there were two peaks,and the minimum of the UHI intensity appeared at 11:00am.The UHI exhibited a spatial structure of multiple centers.