Quantifying Stratospheric Ozone in the Upper Troposphere with in Situ Measurements of HCl
T. P. Marcy,1,2*
D. W. Fahey,1,2
R. S. Gao,1
P. J. Popp,1,2
E. C. Richard,1,2
T. L. Thompson,1
K. H. Rosenlof,1
E. A. Ray,1,2
R. J. Salawitch,3
C. S. Atherton,4
D. J. Bergmann,4
B. A. Ridley,5
A. J. Weinheimer,5
M. Loewenstein,6
E. M. Weinstock,7
M. J. Mahoney3
We have developed a chemical ionization mass spectrometry technique
for precise in situ measurements of hydrochloric acid (HCl)
from a high-altitude aircraft. In measurements at subtropical
latitudes, minimum HCl values found in the upper troposphere
(UT) were often near or below the detection limit of the measurements
(0.005 parts per billion by volume), indicating that background
HCl values are much lower than a global mean estimate. However,
significant abundances of HCl were observed in many UT air parcels,
as a result of stratosphere-to-troposphere transport events.
We developed a method for diagnosing the amount of stratospheric
ozone in these UT parcels using the compact linear correlation
of HCl with ozone found throughout the lower stratosphere (LS).
Expanded use of this method will lead to improved quantification
of cross-tropopause transport events and validation of global
chemical transport models.
2 Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, USA.
3 Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA.
4 Atmospheric Science Division, Lawrence Livermore National Laboratory (LLNL), Livermore, CA 94550, USA.
5 National Center for Atmospheric Research, Boulder, CO 80307, USA.
6 NASA Ames Research Center, Moffett Field, CA 94035, USA.
7 Harvard University, Cambridge, MA 02138, USA.
* To whom correspondence should be addressed. E-mail: tmarcy{at}al.noaa.gov
