The Relationship between Total Precipitable Water and Surface Dew Point

Abstract

Mean monthly and annual values of total precipitable water are compared with mean monthly and annual values of surface dew point for each 5° latitude circle from the equator to 85°S. The correlation coefficients are lower for latitudes 0–20°S than for latitudes 25–85°S. The degree of relationship between mean monthly values of total precipitable water and mean monthly values of surface dew point is good in winter for all latitudes but much weaker in warmer months for latitudes 0–20°S. The computed regression equations give excellent estimates of monthly mean zonally averaged precipitable water from surface dew point for middle and higher latitudes in cooler seasons. Zonally averaged values of the moisture profile power index λ for the Southern Hemisphere are presented. This power index is highly variable (−0.26 to +4.57) even for mean monthly moisture profiles. These results are useful for the zonally averaged climatic models.