Owen R. Cooper (Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, NOAA Chemical Sciences Laboratory, Boulder)

"An update on ever-changing global tropospheric ozone trends"

Tropospheric ozone is a greenhouse gas and pollutant detrimental to human health and crop and ecosystem productivity.  However, it is difficult to observe and quantify on the global scale, due to its acute spatial variability, resulting from its variable lifetime and its range of sources (injection from the stratosphere, or photochemical production from natural and anthropogenic precursor gases) and sinks (surface deposition and chemical destruction).

To improve our understanding of ozone, the International Global Atmospheric Chemistry Project (IGAC) initiated the Tropospheric Ozone Assessment Report (TOAR) in 2014.  With over 230 member scientists and air quality specialists from 36 nations, TOAR’s mission is to provide the research community with an up-to-date scientific assessment of tropospheric ozone’s global distribution and trends from the surface to the tropopause.  TOAR built the world’s largest database of surface ozone observations and generated ozone exposure metrics at thousands of measurement sites around the world.  This seminar will use the results from the first phase of TOAR (2014-2019) to describe the current state of knowledge on global tropospheric ozone trends. 

Trends will be reported for all available surface ozone monitoring sites (2000-2014), long-term monitoring sites in remote locations (1971-2018), the free troposphere (IAGOS aircraft observations, 1994-2016) and the tropospheric column (satellite products, 1979-2020).  While surface trends are highly variable, the burden of evidence points towards an increase of ozone in the northern hemisphere free troposphere, driven by increased photochemical production in the tropics.

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Tuesday, 16.30h to 18.00h