Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
doi:10.5194/acp-2016-908
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
02 Nov 2016
Review status
A revision of this discussion paper is under review for the journal Atmospheric Chemistry and Physics (ACP).
Secondary ozone peaks in the troposphere over the Himalayas
Narendra Ojha1, Andrea Pozzer1, Dimitris Akritidis1,2, and Jos Lelieveld1,3 1Atmospheric Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
2Department of Meteorology and Climatology, School of Geology, Aristotle University of Thessaloniki, Thessaloniki, Greece
3Energy, Environment and Water Research Center, The Cyprus Institute, Nicosia, Cyprus
Abstract. Layers with strongly enhanced ozone concentrations in the middle-upper troposphere, referred to as Secondary Ozone Peaks (SOPs), have been observed in different regions of the world. Here we use the global ECHAM5/MESSy atmospheric chemistry model (EMAC) to (i) investigate the processes causing SOPs, (ii) explore both their frequency of occurrence and seasonality, and (iii) assess their effects on the tropospheric ozone budget over the Himalayas. The vertical profiles of potential vorticity (PV) and a stratospheric ozone tracer (O3s) in EMAC simulations, in conjunction with the structure of SOPs, suggest that SOPs over the Himalayas are formed by Stratosphere-to-Troposphere Transport (STT) of ozone. The spatial distribution of O3s further shows that such effects are in general confined to the northern part of India. Model simulated ozone distributions and backward air trajectories show that ozone rich air masses, associated with STT, originate as far as northern Africa and the North Atlantic Ocean, the Middle-East, as well as nearby regions in Afghanistan and Pakistan, and are rapidly (within 2–3 days) transported to the Himalayas. Analysis of a 15-year (2000–2014) EMAC simulation shows that the frequency of SOPs is highest during the pre-monsoon season (e.g. 11 % of the time in May), while no intense SOP events are found during the July–October period. The SOPs are estimated to enhance the Tropospheric Column Ozone (TCO) over the central Himalayas by up to 26 %.

Citation: Ojha, N., Pozzer, A., Akritidis, D., and Lelieveld, J.: Secondary ozone peaks in the troposphere over the Himalayas, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2016-908, in review, 2016.
Narendra Ojha et al.
Narendra Ojha et al.
Narendra Ojha et al.

Viewed

Total article views: 412 (including HTML, PDF, and XML)

HTML PDF XML Total Supplement BibTeX EndNote
228 163 21 412 13 12 21

Views and downloads (calculated since 02 Nov 2016)

Cumulative views and downloads (calculated since 02 Nov 2016)

Viewed (geographical distribution)

Total article views: 412 (including HTML, PDF, and XML)

Thereof 410 with geography defined and 2 with unknown origin.

Country # Views %
  • 1

Saved

Discussed

Latest update: 30 Apr 2017
Publications Copernicus
Download
Short summary
We investigate the processes, frequency of occurrence and seasonality, and effects of strongly enhanced ozone layers in the middle-upper troposphere (SOPs) over the Himalayas using a global model (EMAC). Rapid transport of stratospheric air masses is found as a key underlying process. Model predicts more frequent SOP events during the pre-monsoon. SOPs are found to significantly enhance the tropospheric ozone column over the Himalayas.
We investigate the processes, frequency of occurrence and seasonality, and effects of strongly...
Share