Simulating gas phase chemistry under atmospheric conditions
Abstract
Gas phase chemistry is the most important pathway for the oxidation and removal of trace gases in the troposphere. Particularly for volatile organic compounds (VOC) the degradation is initiated by the gas phase reaction with OH, NO_3, or ozone. The resulting reaction mechanisms are very nonlinear with respect to several parameters especially some trace gas concentrations and therefore need to be studied at the natural concentration range. The observation and especially the quantification of these gas phase chemical processes in the atmosphere itself is in almost all situations coupled to the natural variability (transport and mixing, emission, deposition) and it is very difficult to separate these processes. Therefore, a number of different simulation chambers were constructed and employed to observe the chemistry of the atmosphere independently from disturbances. These chambers range from smog chambers to clean air facilities and from hundreds of liters to hundreds of m^3. Both sunlight and artificial light is used. Different surface materials have been tested and applied, since the chambers themselves might influence the gas phase chemistry by wall effects (sources and sinks). In this paper we will show the possibilities of and the restrictions to the simulation of tropospheric chemistry using chambers with special emphasis on the simulation chamber SAPHIR at Jülich. We will discuss how size, surface materials, gas supply, illumination, instrumentation, and model-based experiment planing and interpretation can influence the knowledge gain due to chamber experiments.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA....14617W