GML Surface Ozone

Surface Ozone (O₃), also called ground-level ozone, is a critical atmospheric species that drives much of tropospheric photochemistry. It regulates the oxidation capacity of the troposphere, influencing background levels of trace chemicals. Ozone is also a strong greenhouse gas, and is the third most important contributor to greenhouse radiative forcing behind CO₂ and CH₄.

Ozone is produced in the troposphere by photochemical oxidation of CO, CH₄ and non-methane volatile organic carbons (NMVOCs) in the presence of NOx. Stratosphere-troposphere exchange is another source of ozone to the troposphere. Loss of tropospheric ozone takes place through chemical reactions and dry deposition. Ozone is a key trace gas for both the chemistry and radiative balance of the troposphere, and is the principal pollutant associated with photochemical smog.

Surface ozone is considered worldwide to be a pollutant and its atmospheric concentration is regulated by worldwide regulatory agencies. In the United States, it is regulated by the US Environmental Agency (EPA) as one of the 6 'criteria pollutants' under the Clean Air Act and its amendments. ( https://www.epa.gov/ground-level-ozone-pollution).

NOAA GML measures the global background concentrations of surface ozone to provide a baseline to judge the enhancements of ozone due to human activities. GML has been measuring surface ozone at several global locations starting at Barrow, Alaska and Mauna Loa, Hawaii in 1973. The map and table below show the locations of surface ozone measurements.

Please see the following publication for more information on the network:

• Oltmans, S. J., & Levy II, H. (1994). Surface ozone measurements from a global network. Atmospheric Environment, 28(1), 9-24.

Additional station information.

Read More

• Trends of Ozone in the Troposphere