Gps observation which is about 2km far away from radiosonde site is comparable to radiosonde with a absolute bias of 2 . 13mm on precipitable water ( pw ) observation and 1 . 28cm on zenith total delay ( ztd ) 与常规探空观测相比， gps测量的可降水量有很好的代表性。在相距2km时，两种测量手段测量可降水量和总延迟量的平均绝对偏差分别为2 . 13mm和1 . 28cm 。
2.
The variation of ztd is mainly caused by the zenith wet delay ( zwd ) . zenith hydrostatic delay ( zhd ) and zwd from different gps sites exhibit individual features that zhd has a obvious periodic change and zwd is related to weather 总延迟的变化主要是由湿延迟的变化而引起，其中静力延迟变化呈现了明显的周期性，而湿延迟的变化与天气过程相关联。
