Variability in stratospheric water vapor

A variety of possible mechanisms for changing stratospheric water vapor have been proposed related to general circulation changes (Nedoluha et. al, 1999; Rosenlof, 2002). Of interest is that over the past 5 years, there is an apparent reduction in stratospheric water vapor as measured from satellite as well as a difference in calculated trends estimated from satellite and a long-term one station balloon record (Randel et. al, 2004). In situ measurements from frost point balloon as well as satellite measurements will be used to examine temporal variability since the early 1980s. Operational radiosonde data and assimilated wind and temperature fields will be used to examine potential mechanisms for the observed water vapor changes.