Revisiting the stratospheric fountain hypothesis using UARS/HALOE data

Abstract

We use the measurements of water vapour by the Halogen Occultation Experiment (HALOE, version 19) aboard the Upper Atmospheric Research Satellite (UARS) to study some aspects of the entry of air into the stratosphere at the tropical latitudes. The minimum water vapour volume-mixing ratio (vmr) at the tropopause level was found to occur between 50° and 200° in longitude in the tropics. This was observed during January as well as during May representing the winter and summer months in the tropics respectively. Further, the minimum water vapour mixing ratios near the tropopause were found to be generally correlated to lowest temperatures within this longitude band This pattern was generally visible in winter as well as in summer months between 1993-1997 and tends to support the view that air might be entering the stratosphere at specific locations.