Hydrogen radicals, nitrogen radicals, and the production of O3 in the upper troposphere
The concentrations of the hydrogen radicals OH and HO2 in the middle and upper troposphere were measured simultaneously with those of NO, O3, CO, H2O, CH4, non-methane hydrocarbons, and with the ultraviolet and visible radiation field. The data allow a direct examination of the processes that produce O3 in this region of the atmosphere. Comparison of the measured concentrations of OH and HO2 with calculations based on their production from water vapor, ozone, and methane demonstrate that these sources are insufficient to explain the observed radical concentrations in the upper troposphere. The photolysis of carbonyl and peroxide compounds transported to this region from the lower troposphere may provide the source of HOx required to sustain the measured abundances of these radical species. The mechanism by which NO affects the production of O3 is also illustrated by the measurements. In the upper tropospheric air masses sampled, the production rate for ozone (determined from the measured concentrations of HO2 and NO) is calculated to be about 1 part per billion by volume each day. This production rate is faster than previously thought and implies that anthropogenic activities that add NO to the upper troposphere, such as biomass burning and aviation, will lead to production of more O3 than expected.
Wennberg
PO
P. O. Wennberg, T. F. Hanisco, E. J. Hintsa, E. J. Lanzendorf, J. G. Anderson, Department of Chemistry and Chemical Biology and Department of Earth and Planetary Sciences, Harvard University, 12 Oxford Street, Cambridge, MA 02138, USA. L. Ja.
Hanisco
TF
Jaegle
L
Jacob
DJ
Hintsa
EJ
Lanzendorf
EJ
Anderson
JG
Gao
R
Keim
ER
Donnelly
SG
Negro
LAD
Fahey
DW
McKeen
SA
Salawitch
RJ
Webster
CR
May
RD
Herman
RL
Proffitt
MH
Margitan
JJ
Atlas
EL
Schauffler
SM
Flocke
F
McElroy
CT
Bui
TP