EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Trends of tropical tropospheric ozone and its precursors

Audrey Gaudel1,2, Bastien Sauvage3, and the TOAR-OPT Paper 2 "Trends" Team*
Audrey Gaudel and Bastien Sauvage and the TOAR-OPT Paper 2 "Trends" Team
  • 1Cooperative Institute for Research in Environmental Sciences, CU Boulder, CO, USA
  • 2NOAA Chemical Sciences Laboratory, Boulder, CO, USA
  • 3Laboratoire d’Aérologie, Université de Toulouse, CNRS, UPS, Toulouse, France
  • *A full list of authors appears at the end of the abstract

As part of the Tropospheric Ozone Assessment Report Phase 2 (TOAR-II), the Ozone and Precursors in Tropics (OPT) working group counts three deliverables dedicated to quantifying 1) the distribution, 2) the trends of tropospheric ozone (O3) and its precursors (carbon monoxide, CO; formaldehyde, HCHO; nitrogen dioxide, NO2) in the tropics over the past 20-25 years, and 3) their impacts on a global scale. This presentation will focus on the trends estimate. We answer the following scientific questions: How have tropical tropospheric ozone and its precursors changed with time? What sources (e.g. anthropogenic emissions, biomass burning, lightning) drive these trends and to what extent?

To accomplish this, we use both observations and model output.  The observations include in situ measurements of O3 and its precursors from surface sites, sounding balloons (SHADOZ) and instrumented aircraft (IAGOS), as well as ground-based (FTIR) and spatial (IASI, OMI, GOME-2) remote-sensed observations. Global model output come from ECHAM6-HAMMOZ, LMDZ-OR-INCA, MIROC-CHASER, CAM4-Chem, GISS-E2 and the CESM2-WACCM6 ensemble.

The trends estimates are based on monthly anomalies and are calculated after considering climate variabilities such as El Niño- Southern oscillation (ENSO) and quasi-biennial oscillation (QBO).

From IAGOS and SHADOZ ozone profiles, we estimate positive ozone trends between 1994 and 2019 throughout the troposphere above the Americas, Africa, India, Southeast Asia and Malaysia/Indonesia. Trends may reach up to 6 ± 1.6 ppb/decade in the free troposphere and up to 12.5 ± 2 ppb/decade in the boundary layer. There is also considerable regional variability. For example, trends are +0 to 4 ppb/decade in the free troposphere above the remote Pacific and Atlantic SHADOZ stations (1998-2019). According to OMI satellite retrievals, tropospheric ozone burden increases between 2004 and 2021 across the tropical latitude band (20˚N-20˚S) and the trends range between 0.09 Tg/yr (OMI CCD retrieval in the southern hemisphere) and 0.3 Tg/year (OMI/MLS retrieval in the northern hemisphere).

The presentation will also include trends estimates of observed ozone’s precursors such as CO, NO2 and formaldehyde as well as trends estimate of ozone and its precursors from model output.

TOAR-OPT Paper 2 "Trends" Team:

Audrey Gaudel(1,2), Bastien Sauvage(3), Yuqiang Zhang(4), Kai-Lan Chang(1,2), Maria Tsivlidou(3), Ryan Stauffer(5), Anne-M Thompson(5,6), Debra Kollonige(5,7), Corinne Vigouroux(8), Isabelle De Smedt(8), Irina Petropavlovskikh(1,9), Jerald Ziemke(5,10), Daan Hubert(8), Arno Keppens(8), Jean-Christopher Lambert(8), Helen Worden(11), Catherine Wespes(12), Ulas Im(13), Kazuyuki Miyazaki(14), Yann Cohen(15), Tabish Ansari(16), Tim Butler(16,17), Arlene Fiore(18), Suvarna Fadnavis(19), Saumya Singh(20), Gerbrand Koren(21), Bhupendra Bahadur Singh(22), Pallavi Saxena(23), Saurabh Sonwani(24), Giacomo Gerosa(25), Chinmay Mallik(26) AFFILIATIONS (1) Cooperative Institute for Research in Environmental Sciences, CU Boulder, CO, USA; (2) NOAA Chemical Sciences Laboratory, Boulder, CO, USA; (3) Laboratoire d’Aérologie, Université de Toulouse, CNRS, UPS, Toulouse, France; (4) Nicholas School of the Environment, Duke University, Durham, NC, USA; (5) NASA/Goddard Space Flight Center (GSFC), Greenbelt, MD, USA; (6) University of Maryland-Baltimore County, Baltimore, MD, USA; (7) Science Systems and Applications, Inc., Lanham, MD, USA; (8) Royal Belgian Institute for Space Aeronomy (BIRA-IASB), Uccle, Belgium; (9) NOAA Global Monitoring Laboratory, Boulder, CO, USA; (10) Morgan State University, Baltimore, Maryland, USA; (11) Atmospheric Chemistry Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder, CO, USA; (12) Spectroscopy, Quantum Chemistry and Atmospheric Remote Sensing (SQUARES), Université libre de Bruxelles (ULB), Brussels, Belgium; (13) Department of Environmental Science/Interdisciplinary Centre for Climate Change, Aarhus University, Frederiksborgvej 400, Roskilde, Denmark; (14) Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA; (15) Laboratoire des Sciences du Climat et de l'Environnement (LSCE), UMR 8212, Gif-sur-Yvette, France; (16) Research Institute for Sustainability, Helmholtz Center Potsdam, Germany; (17) Institut Für Meteorologie, Freie Universität Berlin, Germany; (18) Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA; (19) Department of Civil & Environmental Engineering I University of California, Berkeley, CA, USA; (20) DST-Mahamana Centre of Excellence in Climate Change Research, Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi, Uttar Pradesh, India; (21) Copernicus Institute of Sustainable Development, Utrecht University, Utrecht, the Netherlands; (22) Centre for Climate Change Research, Indian Institute of Tropical Meteorology, Ministry of Earth Sciences, Pune 411 008, India; (23) Department of Environmental Sciences, Hindu College University of Delhi New Delhi, Delhi, India; (24) Department of Environmental Studies, Zakir Husain Delhi College, University of Delhi, New Delhi, India; (25) Department of Mathematics and Physics, Catholic University of the Sacred Heart, Brescia, Italy; (26) School of Earth Sciences, Department of Atmospheric Science, Central University of Rajasthan, Rajasthan, India.

How to cite: Gaudel, A. and Sauvage, B. and the TOAR-OPT Paper 2 "Trends" Team: Trends of tropical tropospheric ozone and its precursors, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-9365,, 2023.