RELATIONSHIPS BETWEEN TROPOSPHERIC WATER-VAPOR AND SURFACE-TEMPERATURE AS OBSERVED BY RADIOSONDES

Using radiosonde data from 50 stations for 1973-1990, we quantify relationships between surface air temperature (T(s)) and precipitable water vapor (W) for different time scales. Monthly mean observations are fairly well described by an equation of the form ln W = A + B T(s), but the coefficients A and B depend on the T(s) range considered. At high T(s), 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(s) are well correlated only outside the tropics, but on longer time scales, there is some evidence of positive trends in both W and T(s) at most of the stations studied. Thus the relationship between W and T(s) depends on the time scales and geographic region considered.