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Chemical processes related to net ozone tendencies in the free troposphere

Version 2 2024-06-04, 04:07
Version 1 2023-10-25, 05:31
journal contribution
posted on 2024-06-04, 04:07 authored by H Bozem, TM Butler, MG Lawrence, H Harder, M Martinez, D Kubistin, J Lelieveld, H Fischer
Ozone (O3) is an important atmospheric oxidant, a greenhouse gas, and a hazard to human health and agriculture. Here we describe airborne in situ measurements and model simulations of O3 and its precursors during tropical and extratropical field campaigns over South America and Europe, respectively. Using the measurements, net ozone formation/destruction tendencies are calculated and compared to 3-D chemistry-transport model simulations. In general, observation-based net ozone tendencies are positive in the continental boundary layer and the upper troposphere at altitudes above ĝ1/4 ĝ€6ĝ€km in both environments. On the other hand, in the marine boundary layer and the middle troposphere, from the top of the boundary layer to about 6-8ĝ€km altitude, net O3 destruction prevails. The ozone tendencies are controlled by ambient concentrations of nitrogen oxides (NO < i > x < /i > ). In regions with net ozone destruction the available NO < i > x < /i > is below the threshold value at which production and destruction of O3 balance. While threshold NO values increase with altitude, in the upper troposphere NO < i > x < /i > concentrations are generally higher due to the integral effect of convective precursor transport from the boundary layer, downward transport from the stratosphere and NO < i > x < /i > produced by lightning. Two case studies indicate that in fresh convective outflow of electrified thunderstorms net ozone production is enhanced by a factor 5-6 compared to the undisturbed upper tropospheric background. The chemistry-transport model MATCH-MPIC generally reproduces the pattern of observation-based net ozone tendencies but mostly underestimates the magnitude of the net tendency (for both net ozone production and destruction),

History

Journal

Atmospheric chemistry and physics

Volume

17

Pagination

10565-10582

Location

Katlenburg-Lindau, Germany

ISSN

1680-7316

eISSN

1680-7324

Language

eng

Publication classification

C Journal article, C1.1 Refereed article in a scholarly journal

Copyright notice

2017, The Authors

Issue

17

Publisher

European Geosciences Union

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