On the Relationship between Water Vapor over the Oceans and Sea Surface Temperature

Abstract

Monthly mean precipitable water data obtained from passive microwave radiometry (SMMR) are correlated with NMC-blended sea surface temperature data. It is shown that the monthly mean water vapor content of the atmosphere above the oceans can generally be prescribed from the sea surface temperature with a standard deviation of O.36 g cm?2. The form of the relationship between precipitable water and sea surface temperature in the range Ts gt; 15°C also resembles that predicted from simple arguments based on the Clausius-Clapeyron relationship. The annual cycle of the mass of SMMR water vapor integrated over the global oceans is shown to differ from analyses of fully global water vapor data in both phase and amplitude, and these difference paint to a significant influence of the continents on water vapor. Regional scale analyses of water vapor demonstrate that monthly averaged water vapor data, when contrasted with the bulk sea surface temperature relationship developed in this study, reflect various known characteristics of the time mean large-scale circulation over the oceans. A water vapor parameter is introduced to highlight the effects of large-scale motion on atmospheric water vapor. Based on the magnitude of this parameter, it is shown that the effects of large-scale flow on precipitable water vapor are regionally dependent, but for the most part, the influence of circulation is generally less than about ±20% of the seasonal mean.