L. Pan et al., HEMISPHERIC ASYMMETRIES AND SEASONAL-VARIATIONS OF THE LOWERMOST STRATOSPHERIC WATER-VAPOR AND OZONE DERIVED FROM SAGE-II DATA, J GEO RES-A, 102(D23), 1997, pp. 28177-28184
The distributions of water vapor and ozone in the lowermost stratosphe
re, the part of the stratosphere between the tropopause and the 380-K
potential temperature surface, are examined using the Stratospheric Ae
rosol and Gas Experiment II measurements for the period of March 1989
to February 1990. The monthly mean values of water vapor and ozone are
computed for the stratospheric portions of the 320-K and 350-K potent
ial temperature surfaces for both hemispheres. We find a strong season
al cycle in the water vapor mixing ratio on the 320-K potential temper
ature surface for both hemispheres, with maximum values in the summer
season and minimum values in early spring. The seasonal cycle at the 3
50-K isentrope is similar to that at the 320 K but with a reduced ampl
itude. Comparisons with their distributions on the 420-K isentrope are
made in order to explore information on stratosphere-troposphere exch
ange via the extratropical tropopause. Both water vapor and ozone data
suggest that troposphere to stratosphere exchange across the extratro
pical tropopause has a significant influence on the lowermost stratosp
here, especially for the northern hemisphere in the summer season.