Stratospheric Mean Ages and Transport Rates from Observations of
Carbon Dioxide and Nitrous Oxide
K. A. Boering,
S. C. Wofsy,
*
B. C. Daube,
H. R. Schneider,
M. Loewenstein,
J. R. Podolske,
T. J. Conway
Measurements of stratospheric carbon dioxide (CO2) and
nitrous oxide (N2O) concentrations were analyzed to
investigate stratospheric transport rates. Temporal variations in
tropospheric CO2 were observed to propagate into the
stratosphere, showing that tropospheric air enters the lower tropical
stratosphere continuously, ascends, and is transported rapidly (in less
than 1 month) to both hemispheres. The mean age A of
stratospheric air determined from CO2 data is approximately
5 years in the mid-stratosphere. The mean age is mathematically
equivalent to a conserved tracer analogous to exhaust from
stratospheric aircraft. Comparison of values for A from
models and observations indicates that current model simulations likely underestimate pollutant concentrations from proposed stratospheric aircraft by 25 to 100 percent.
K. A. Boering, S. C. Wofsy, B. C. Daube, H. R. Schneider, Division
of Engineering and Applied Sciences and the Department of Earth and
Planetary Sciences, Harvard University, Cambridge, MA 02138, USA.
M. Loewenstein and J. R. Podolske, NASA Ames Research Center, Moffett
Field, CA 94035, USA.
T. J. Conway, Climate Monitoring and Diagnostics Laboratory, National
Oceanic and Atmospheric Administration, Boulder, CO 80303, USA.
*
To whom correspondence should be addressed.
