SiteTesting with IRA-935 Hygrometer and Statistical Analyses

A brief description of infrared IRA-935 water vapour measuring instrument is presented and integrated vertical water vapour content W₀ in the atmosphere at Gaomeigu and Fenghuangshan sites and precision analyses are given in the paper.The daily variation and distributions of W0 in a whole year and monthly-average W₀ measurements at these two sites are discussed in more detail.The statistical results of the observational data in the whole year are also analy sed and discussed.