Sc. Wofsy et al., VERTICAL TRANSPORT RATES IN THE STRATOSPHERE IN 1993 FROM OBSERVATIONS OF CO2, N2O AND CH4, Geophysical research letters, 21(23), 1994, pp. 2571-2574
Measurements of CO2, N2O and CH4 are analyzed to define hemispheric av
erage vertical exchange rates in the lower stratosphere from November
1992 to October 1993. Effective vertical diffusion coefficients were s
mall in summer, less-than-or-equal-to 1 m2s-1 at altitudes below 25 km
; values were similar near the tropopause in winter, but increased mar
kedly with altitude. The analysis suggests possibly longer residence t
imes for exhaust from stratospheric aircraft, and more efficient trans
port from 20 km to the middle stratosphere, than predicted by many cur
rent models. Seasonally-resolved measurements of stratopheric CO2 and
N2O provide significant new constraints on rates for global-scale vert
ical transport.