Tropospheric Ozone Assessment Report, Phase II (TOAR-II, 2020-2024)


Join us for the TOAR-II Quickstart Event, September 16, 2020

The second phase of the Tropospheric Ozone Assessment Report (TOAR-II) is beginning with an open call to the research community to build the assessment and coordinate new studies on ozone’s global distribution and trends, as well as impacts on human health, vegetation and climate.  To learn more about, or to get involved with this grass roots effort please attend the TOAR-II Quickstart Event on September 16, 2020. This 90-minute virtual event will include a series of short presentations from the TOAR-II Steering Committee covering the scope and goals of the Activity, followed by a Q&A session.

Please register for the TOAR-II Quickstart Event on Sep 16, 2020 (12:00-13:30 UTC) at:

To join the TOAR-II email list, sign-up here



As of February 2020, TOAR has entered its second phase (TOAR-II), the first phase having been completed in 2019. The TOAR mission continues, with TOAR-II providing updated and extended information on tropospheric ozone.

Specifically, the goals of TOAR-II are:

  1. TOAR Ozone Data Portal:  Update the ozone observations in the TOAR surface ozone database to include all recent observations (since 2014), and include data from new sites and regions, as well as ozone precursor and meteorological data.  Develop methods for including historical data (pre-1975) and create working links to repositories of free tropospheric observations.
  2. TOAR publications:  Exploit the new observational datasets collected by Goal 1 (with data through 2020) to provide an updated state of the science estimate of ozone’s global distribution and trends relevant to climate, human health and vegetation.  Extend the statistical toolbox and metrics of the TOAR trend analyses.  These results will be published in the open-access, peer-reviewed literature.
  3. Involve scientists from the atmospheric sciences community, as well as statisticians and scientists who focus on broader issues of global change and sustainability, to identify outstanding science questions in relation to tropospheric ozone.  The range of topics can be expanded beyond the scope of the original TOAR effort to investigate the impacts of tropospheric ozone on climate, human health and vegetation, and to address urban-scale issues in addition to the regional and global scale.
  4. Maximize exploitation of the TOAR Surface Ozone Database by, 1) helping scientists around the world, beyond the TOAR effort, to apply the database to new analyses, and 2) exploring new data science methods to improve the analysis of global ozone trends and their attribution.


To join the TOAR-II email list, sign-up here

A citable presentation on TOAR-II can be downloaded here


Current Working Groups

Satellite Ozone Working Group

Oceania Working Group


Procedural Documents

TOAR-II Scope and Roadmap for Working Groups and Publications

TOAR-II Guidelines for Working Groups

TOAR-II Working Group application procedure


Upcoming Events

TOAR-II Quickstart Virtual Event
IGAC Sponsored

Register for the Event Here, TOAR II Website

Past Events

Workshop on Ozone in the Lower Atmosphere in Oceania: First Regional Workshop of the Tropospheric Ozone Assessment Report phase II (TOAR-II) (Postponed to Sep or Oct 2020)
IGAC Sponsored
Aspendale, Victoria, Australia

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