European Facility For Airborne Research Nov. 29, 2020, 03:00
|Name||In Situ Trace Gas Measurements|
|Description||There are many trace gases, which can be grouped by their chemical property and structure. The chemical reactivity of these species can span as much as 10 orders of magnitude. They range from the highly reactive hydroxyl radical, OH, which has an atmospheric residence time of less than one second, to highly stable chlorofluorocarbons, which are highly resistant to destruction via chemical or physical processes such as photolysis, which can have atmospheric lifetimes in excess of 100 years. This temporal range means that gas-phase measurements can be used to probe oxidative capacity on a very local scale and cloud processing and vertical transport dynamics on a larger scale through to large-scale or long-range transport across intercontinental dimensions.
Consequently, this EWG considers the techniques used to determine the presence and abundance of gas-phase species, including interactions with electromagnetic radiation (spectroscopy), chemical reagents (chemical conversion), and a direct measure of the mass-to-charge ratio of the ionized species of interest. Many of the techniques discussed in this EWG here derive from laboratory instrumentation with suitable modifications to enable their transfer to the aircraft environment.