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Measurements of the sum of HO2NO2 and CH3O2NO2 in the remote troposphere
1University of California at Berkeley, Department of Chemistry, Berkeley, CA, USA
2National Center for Atmospheric Research, Atmospheric Chemistry Division, Boulder, CO, USA
3University of California at Berkeley, Department of Earth and Planetary Science, Berkeley, CA, USA
4Lawrence Berkeley National Laboratory, Division of Energy and Environment Technologies, Berkeley, CA, USA
*now at: University of Toronto, Department of Chemistry, Toronto, ON, Canada
Abstract. The chemistry of peroxynitric acid (HO2NO2) and methyl peroxynitrate (CH3O2NO2)is predicted to be particularly important in the upper troposphere where temperatures are frequently low enough that these compounds do not rapidly decompose. At temperatures below 240K, we calculate that about 20% of NOy in the mid- and high-latitude upper troposphere is HO2NO2. Under these conditions, the reaction of OH with HO2NO2 is estimated to account for as much as one third of the permanent loss of hydrogen radicals. During the Tropospheric Ozone Production about the Spring Equinox (TOPSE) campaign, we used thermal dissociation laser-induced fluorescence (TD-LIF) to measure the sum of peroxynitrates (
PNs
HO2NO2+CH3O2NO2+PAN+PPN+...) aboard the NCAR C-130
research aircraft. We infer the sum of HO2NO2 and
CH3O2NO2 as the difference between PN measurements
and gas chromatographic measurements of the two major peroxy acyl nitrates,
peroxy acetyl nitrate (PAN) and peroxy propionyl nitrate (PPN). Comparison
with NOy and other nitrogen oxide measurements confirms the importance
of HO2NO2 and CH3O2NO2 to the reactive nitrogen
budget and shows that current thinking about the chemistry of these species
is approximately correct. During the spring high latitude conditions sampled
during the TOPSE experiment, the model predictions of the contribution of
(HO2NO2+CH3O2NO2) to NOy are highly
temperature dependent: on average 30% of NOy at 230K, 15% of
NOy at 240K, and 
5% of NOy above 250K. The temperature
dependence of the inferred concentrations corroborates the contribution of
overtone photolysis to the photochemistry of peroxynitric acid. A model that
includes IR photolysis (J=1x10-5s-1) agreed with the observed sum of
HO2NO2+CH3O2NO2 to better than 35% below 240K where the concentration of these species is largest.Final Revised Paper (PDF, 568 KB) Discussion Paper (ACPD)
Citation: Murphy, J. G., Thornton, J. A., Wooldridge, P. J., Day, D. A., Rosen, R. S., Cantrell, C., Shetter, R. E., Lefer, B., and Cohen, R. C.: Measurements of the sum of HO2NO2 and CH3O2NO2 in the remote troposphere, Atmos. Chem. Phys., 4, 377-384, 2004. Bibtex EndNote Reference Manager
