Abstract
Atmospheric chemists have recently focused on the relevance of the NO 2* + H2O → OH + HONO reaction to local air quality. This chemistry has been considered not relevant for the troposphere from known reaction rates until nowadays. New experiments suggested a rate constant of 1.7 × 10-13 cm3 molecule-1 s-1, which is an order of magnitude faster than the previously estimated upper limit of 1.2 × 10-14 cm3 molecule-1 s-1, determined by Crowley and Carl (1997). Using the new global model, NMMB/BSC Chemical Transport Model (NMMB/BSC-CTM), simulations are presented that assess the potential significance of this chemistry on global air quality. Results show that if the NO2* chemistry is considered following the upper limit kinetics recommended by Crowley and Carl (1997), it produces an enhancement of ozone surface concentrations of 4-6 ppbv in rural areas and 6-15 ppbv in urban locations, reaching a maximum enhancement of 30 ppbv in eastern Asia. Moreover, NO 2 enhancements are minor (<0.01 ppbv) in background regions and reach maximum daytime values of 1-6 ppbv. Similarly, HONO exhibits negligible increases, 8-9 pptv in urban settings. Enhancements in the concentration of OH are around 14-17 × 105 molec cm-3. Decreases in the concentration of O3 and its precursors are also identified but to a lesser degree. In order to quantify the role of the two kinetic rates measured, model simulations are compared after incorporating both reaction rate constants. Maximum O3 difference enhancements from 5 to 10 ppbv are modeled over locations where high NOx emissions are present; however, differences are small in most parts of the globe. 2012. American Geophysical Union. All Rights Reserved.
Original language | English (US) |
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Article number | D13301 |
Journal | Journal of Geophysical Research Atmospheres |
Volume | 117 |
Issue number | 13 |
DOIs | |
State | Published - 2012 |
All Science Journal Classification (ASJC) codes
- Geophysics
- Forestry
- Oceanography
- Aquatic Science
- Ecology
- Water Science and Technology
- Soil Science
- Geochemistry and Petrology
- Earth-Surface Processes
- Atmospheric Science
- Earth and Planetary Sciences (miscellaneous)
- Space and Planetary Science
- Palaeontology