Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
doi:10.5194/acp-2017-194
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
15 Mar 2017
Review status
This discussion paper is under review for the journal Atmospheric Chemistry and Physics (ACP).
Modeling inter-continental transport of ozone in North America with CAMx for the Air Quality Model Evaluation International Initiative (AQMEII) Phase 3
Uarporn Nopmongcol, Zhen Liu, Till Stoeckenius, and Greg Yarwood Ramboll Environ, 773 San Marin Dr., Suite 2115, Novato, CA 94945
Abstract. Inter-continental ozone (O3) transport extends the geographic range of O3 air pollution impacts and makes local air pollution management more difficult. Phase 3 of the Air Quality Modeling Evaluation International Initiative (AQMEII-3) is examining the contribution of inter-continental transport to regional air quality by applying regional scale atmospheric models jointly with global models. We investigate methods for tracing O3 from global models within regional models. The CAMx photochemical grid model was used to track contributions from boundary condition (BC) O3 over a North America modeling domain for calendar year 2010 using a built-in tracer module called RTCMC. RTCMC can track BC contributions using chemically reactive tracers and also using inert tracers in which deposition is the only sink for O3. Lack of O3 destruction chemistry in the inert tracer approach leads to over estimation biases that can exceed 10 ppb. The flexibility of RTCMC also allows tracking O3 contributions made by groups of vertical BC layers. The largest BC contributions to seasonal average daily maximum 8-hour averages (MDA8) of O3 over the US are found to be from the mid-troposphere with small contributions from the upper troposphere-lower stratosphere. Contributions from the lower troposphere are shown to not penetrate very far inland. Higher contributions in the Western than the Eastern US, reaching an average of 57 ppb in Denver for the 30 days with highest MDA8 O3 in 2010, present a significant challenge to air quality management approaches based solely on local or US-wide emission reductions. The substantial BC contribution to MDA8 O3 in the Intermountain West means regional models are particularly sensitive to any biases and errors in the BCs. A sensitivity simulation with reduced BC O3 in response to 20 % lower emissions in Asia found a near linear relationship between the BC O3 changes and surface O3 changes in the Western US in all seasons and across the US in fall and winter. However, the surface O3 decreases are small: below 1 ppb in spring and below 0.5 ppb in other seasons.

Citation: Nopmongcol, U., Liu, Z., Stoeckenius, T., and Yarwood, G.: Modeling inter-continental transport of ozone in North America with CAMx for the Air Quality Model Evaluation International Initiative (AQMEII) Phase 3, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2017-194, in review, 2017.
Uarporn Nopmongcol et al.
Uarporn Nopmongcol et al.
Uarporn Nopmongcol et al.

Viewed

Total article views: 189 (including HTML, PDF, and XML)

HTML PDF XML Total Supplement BibTeX EndNote
128 53 8 189 9 4 7

Views and downloads (calculated since 15 Mar 2017)

Cumulative views and downloads (calculated since 15 Mar 2017)

Viewed (geographical distribution)

Total article views: 189 (including HTML, PDF, and XML)

Thereof 188 with geography defined and 1 with unknown origin.

Country # Views %
  • 1

Saved

Discussed

Latest update: 26 Mar 2017
Publications Copernicus
Download
Short summary
CAMx regional model was used to examine contribution of inter-continental transport over North America as part of the AQMEII Phase III. Largest boundary condition (BC) contributions to ozone (O3) are from the mid-troposphere. Lower emissions in Asia by 20 % causes a near linear relationship between the BC O3 changes and surface O3 changes in the western US, but the changes are less than 1 ppb. Using inert tracers leads to high bias over 10 ppb compared to using chemically reactive tracers.
CAMx regional model was used to examine contribution of inter-continental transport over North...
Share