Troposphere, Free Radicals and Volcanic Emissions
Emeritus Prof. Ulrich Platt's research focuses on the release of halogen radicals and volatile halogenated hydrocarbons in the boundary layer. We also study chemical instabilities in the atmosphere and the emission of radicals from volcanoes. The core research method is the principle of Differential Optical Absorption Spectroscopy (DOAS), which we are constantly developing further.
Free radicals (OH, HO2, NO3, CL, Br, I, ClO, BrO, IO, ...) play key roles in atmospheric chemistry, as they cause the degradation of most natural and anthropogenic atmospheric pollutants (“self-cleaning of the atmosphere”), control most chemical processes, especially ozone formation in the troposphere, and can initiate chemical chain reactions. Due to their high chemical reactivity, the atmospheric lifetimes of free radicals are typically short and so are their atmospheric concentrations.
Our research focuses on the further development of spectroscopic measurement methods that allow continuous observation of the temporal and spatial variation of free radical concentrations in the troposphere. The observations are interpreted in terms of (1) the source strength of e.g. the marine boundary layer, sea ice, salt lakes and volcanoes with respect to halogen radicals, as well as (2) the relationship between variation of source strength and the state of the emitting bodies (e.g. monitoring of volcanic activity), and (3) the reaction rates of atmospheric chemical processes.
Tropospheric Chemistry
Free radicals are key components in the atmosphere:
- They lead to the distruction of most pollutants that enter the atmosphere by natural or anthropogenic processes.
- Free radicals control most chemical processes, e.g. the creation of ozone in the troposphere.
- Free Radicals can create 'chain reactions'.
Due to their high chemical reactivity, the atmospheric lifetimes of free radicals are typically short and thus also their atmospheric concentrations.
Our group focuses on:
- the further development of spectroscopic measurement methods (in particular Differential Optical Absorption Spectroscopy - DOAS), which enable continuous observation of the temporal and spatial concentration variation of free radicals in the troposphere
- carrying out a wide variety of measurement campaigns, e.g. airborne in the upper troposphere or ground-based in polar regions, on salt lakes and at volcanoes
- the interpretation of the observations with regard to (1) the source strength of e.g. the marine boundary layer, sea ice, salt lakes and volcanoes with respect to halogen radicals, as well as (2) the relationship between variation of the source strength and the state of the emitting bodies (e.g. monitoring of volcanic activity), and (3) the reaction rates of atmospheric chemical processes.
