The daily variation and seasonly variation of Wind Shear over the urban boundary layer have been discussed . A Few Results were got as bellow :(1) there is a maximum of Wind Shear between 8:00am and 10:00am and the same was between 19:00 pm and 21:00pm ;

• 并进一步讨论了城市下垫面下的风切变的日变化和季节变化得出如下结论:(1)风切变的日变化在横向随时间的变化上可以看出大部分情况下在上午8:00-10:00之间有一个极大值,下午19:00-21:00有一个极大值,在变化上表现出近似正弦曲线的变化;