Relationships between Tropospheric Water Vapor and Surface Temperature as Observed by Radiosondes

Using radiosonde data from 50 stations for 19731990, we quantify relationships between surface air temperature (Ts) and precipitable water vapor (W) for different time scales. Monthly _mean observations are fairly well described b 7an equation of the form In W = A + B Ts, but the coefficients _4 and B depend on the Ts range considered. At high T•, the relationship is poor. This relationship and relationships between sea surface temperature (SST) and W based on satellite microwave observations over oceans are in remarkably good agreement over restricted SST ranges. Monthly and annual anomalies of W and T• are well correlated only outside the tropics, but on longer time scales, there is some evidence of positive trends in both W and T• at most of the stations studied. Thus the relationship between W and T• depends on the time scales and geographic region considered. Introduction Global radiosonde data, from continental and island stations, o.ffer an opportunity to examine the relationships over a wider temperature ange, for a longer period, and with spatially and temporally consistent data, because radiosonde reports yield both W and Ts. In the following sections, we describe such a data set, and present relationships between W and T• for both monthly mean data and monthly and annual anomalies. Trends in both variables are also presented.