EGU23-5293, updated on 14 Sep 2023
EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Present-day distribution of tropospheric ozone and precursors in the tropics

Bastien Sauvage1, Audrey Gaudel2,3, Suvarna Fadnavis4, Maria Tsivlidou1, Pallavi Saxena5, Brice Barret1, Meng Li2,3, Bhupendra Bahadur Singh4, Renu Masiwal6, Saurabh Sonwani7, Ulas Im8, Yann Cohen9, Saumya Singh10, Daan Hubert11, Arno Keppens11, Jean-Christopher Lambert11, Catherine Wespes12, Irina Petropavlovskikh2,13, Giacomo Gerosa14, Helen Worden15, and the List of co-authors*
Bastien Sauvage et al.
  • 1Laboratoire Aerologie / CNRS, Atmospheric Physics, Toulouse, France (
  • 2Cooperative Institute for Research in Environmental Sciences, CU Boulder
  • 3NOAA Chemical Sciences Laboratory
  • 4Indian Institute of Tropical Meteorology (Ministry of Earth Sciences), Pune, India.
  • 5Department of Environmental Sciences, Hindu College, University of Delhi, Dehli, India
  • 6National Physical Laboratory - India | NPL • Division of Radio and Atmospheric Sciences (NPL)
  • 7Department of Environmental Studies Zakir Husain Delhi College, University of Delhi, New Delhi, India
  • 8Department of Environmental Science, Atmospheric Environment Section, Atmospheric Modelling Group, Frederiksborgvej 399, 4000, Roskilde, Denmark
  • 9Laboratoire des Sciences du Climat et de l'Environnement (LSCE), UMR 8212, Gif-sur-Yvette, France
  • 10Department of Civil & Environmental Engineering, University of California, Berkeley, CA, USA
  • 11Royal Belgian Institute for Space Aeronomy, BIRA-IASB, Brussels, Belgium
  • 12ULB, Belgium
  • 13NOAA Global Monitoring Laboratory
  • 14Dipartimento di Matematica e Fisica "Niccolò Tartaglia", Università Cattolica del S.C., via Musei 41, 25121 Brescia
  • 15Atmospheric Chemistry Observations & Modeling (ACOM) Laboratory, National Center for Atmospheric Research, P. O. Box 3000, Boulder CO 80307 USA
  • *A full list of authors appears at the end of the abstract

As part of the Ozone and Precursors in the Tropics (OPT) working group of the Tropospheric Ozone Assessment Report Phase 2 (TOAR-II), we present the first results on the distribution of tropospheric ozone (O3) and its precursors (carbon monoxide, CO; formaldehyde, HCHO; nitrogen dioxide, NO2) in the tropics over the past 20-25 years. The goal is to give an overview of the seasonal, geographical and vertical variabilities of tropical tropospheric O3 and its precursors. To do so, we use in situ measurements of O3 and its precursors from surface sites, sounding balloons (SHADOZ) and instrumented aircraft (IAGOS and ATOM), as well as ground-based (FTIR) and spatial (IASI, OMI, GOME-2) remote-sensed observations. The observations are averaged monthly over the longest available time-period as well as over the first five years of the time period. The results for these two time periods give the context to interpret distributions and variabilities of O3 and its precursors over the most recent five years as we call it “Present-day”.  Special emphasis is given to the differences of O3 and its precursors’ distributions between remote and polluted regions and to the relationships between the gaseous species. Model output will be included to fill gaps in space and time when necessary to help the interpretation of the analysis based on observations.

From IAGOS measurements, the highest O3 and CO maxima occur in the lower troposphere of Northern Hemisphere Africa, which remains the most influenced by biomass burning. CO maxima are attributed using SOFT-IO model to anthropogenic emissions by 60%. Second maxima are observed in the lower troposphere of Asia, mostly due to anthropogenic emissions. The highest amount of transported CO in the tropics originates from Africa.

List of co-authors:

Sauvage B. (1), Gaudel A. (2,3), Fadnavis S. (4), Tsivlidou M. (1), Saxena P. (5), Brice Barret (1), Li M. (2,3), Singh B. B. (4) Masiwal R. (6), Sonwani S. (7), Im U. (8), Cohen Y. (9), Singh S. (10), Hubert D. (11), Keppens A. (11), Lambert J.-C. (11), Wespes C. (12), Petropavlovskikh I. (2,13), Gerosa G. (14), Worden H. (15), Mallik C. (16), Vigouroux C. (11), Kalabokas P. (17), Koren G. (18)

How to cite: Sauvage, B., Gaudel, A., Fadnavis, S., Tsivlidou, M., Saxena, P., Barret, B., Li, M., Singh, B. B., Masiwal, R., Sonwani, S., Im, U., Cohen, Y., Singh, S., Hubert, D., Keppens, A., Lambert, J.-C., Wespes, C., Petropavlovskikh, I., Gerosa, G., and Worden, H. and the List of co-authors: Present-day distribution of tropospheric ozone and precursors in the tropics, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5293,, 2023.