The Reconstruction of the Historic Record (1896-Present) of Tropospheric Ozone
The Tropospheric Ozone Assessment Report (TOAR), is an Activity of the International Global Atmospheric Chemistry Project (IGAC), (http://www.igacproject.org/TOAR). The mission of TOAR is to provide the research community with an up-to-date scientific assessment of tropospheric ozone’s global distri...
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|Summary:||The Tropospheric Ozone Assessment Report (TOAR), is an Activity of the International Global Atmospheric Chemistry Project (IGAC), (http://www.igacproject.org/TOAR). The mission of TOAR 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 and to provide the ozone metrics necessary for quantifying ozone’s impact on human health and crop/ecosystem productivity.Tropospheric ozone concentration measurements from 1896-present have been collected from multiple sources and for the first time put together in a harmonized way. The historic surface ozone record 1896-1975 and tropospheric ozone record 1933-present have been constructed from measurements that pass the four criteria: (a) instrumentation whose ozone response can be traced to modern tropospheric ozone measurement standards, (b) samples taken when there is low probability of chemical interference (c) sampling locations, heights and times when atmospheric mixing minimises vertical gradients of ozone in the planetary boundary layer above and around the measurement location and (d) the laugh test.In total, 60 acceptable sets of surface ozone measurements are currently identified, commencing in Europe in 1896, Greenland in 1932 and globally by the late 1950’s. Similarly there are 7 sets of observations of ozone in the free troposphere that cover 1933-1955. Some early urban observations are also identified. These time series are matched with modern measurements (1970-present) from the Tropospheric Ozone Assessment Report (TOAR) Ozone Database, which contains hourly data from over 10,000 sites around the world.Key basic questions that are addressed here are: how have regional ozone changes, both increases and decreases, been distributed globally over the last 120 years; when did ozone pollution appear in cities; how does urban and regional ozone in the Southern Hemisphere compare with that in the Northern Hemisphere; and what are the health and crop ...|