Global Lower Mesospheric Water Vapor Revealed by LIMS Observations

Abstract

The Limb Infrared Monitor of the Stratosphere (LIMS) water vapor channel data analysis has been extended from the 1. mb level ( 48 km) to the .3 mb level ( 60 km) through a radiance averaging procedure and better understanding of systematic errors. The data show H2O mixing ratio peaks near the .5 mb level varying from 4 to 7 ppmv with latitude and season. Above this level the mixing ratio drops off quickly with altitude but, due to experimental uncertainties, at an uncertain rate. The stratospheric results are virtually the same as determined from the archived LIMS results with a tropical hygropause and enhanced H2O concentration in the lower levels at high winter latitudes.