the ground － based GPS data of JICA program，the characteristics of precipitable water in Western Sichuan Plateau
were analyzed in his paper． Comparison the estimates of precipitable water from GPS measurements with sonde observations shows that
the mean error is 0． 17 mm，that is，the precision of the estimates of precipitable water from GPS measurements can fill the requirements
of meteorological application． It is found that annual precipitable water in north part of Western Sichuan Plateau is 3 289． 6 mm，
while in south part that is 8 164． 4 mm． The precipitable water in the nighttime is a bit higher than that in the daytime． Precipitable
water contributes most in summer，secondarily in autumn，least in winter，which shows that there are distinctive dry and wet seasons in
Western Sichuan Plateau． Meanwhile，precipitable water varies with month obviously，as well as its monthly variation trend in the
nighttime is almost the same as that in the daytime．

Based on theNCEP reanalysis data(2. 5°×2. 5°) from 1948 to 2007, this paper analyzed the long-term mean characteristics and the seasona,l annual and decadalvariations ofprecipitablewater in Sichuan in recent60 years. It is found thatannualprecipitablewater in Sichuan is 181. 30 kg·m-2, and the spatialdistribution ofprecipitablewater is obviously unequalwith high inWestSichuan Plateau and low in Sichuan Basin. The precipitable water varies with season obviously, which ismost (74. 33 kg·m-2) in summer and least in winter. Themonthly precipitablewater is least(5. 82 kg·m-2) in January andmost(25. 77 kg·m-2) in July,and it increases from Februarywhile decreases from August. In recent60 years, precipitablewaterwaves around the average levelwith a slightdownward tendency. Meanwhile, the precipitablewater in rainy years is 1. 15 times asmuch as that in dry years.