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UP: Fachverband Umweltphysik

UP 8: Methoden I

UP 8.4: Talk

Thursday, March 5, 2009, 15:12–15:24, VMP 8 R206

Measurement of trace gas fluxes from point sources with Multi-Axis Differential Optical Absorption Spectroscopy — •Matthias Fickel, Leif Vogel, Christoph Kern, and Ulrich Platt — Institut für Umweltphysik, Universität Heidelberg, 69120 Heidelberg

Many spatially defined emission sources of trace gases such as industrial stacks and volcanoes are difficult to access for in situ measurements. For the determination of fluxes, it is also mandatory to assess the overall emitted amount of trace gases, taking into account spatial and temporal fluctuations.

Results of a diploma thesis are presented, in which automated measurements of trace gases were implemented. The fluxes are determined by spectroscopical analysis of sunlight passing through the emitted plume employing MAX-DOAS (Multi Axis - Differential Optical Absorption Spectroscopy) instruments.

Next to gas concentrations, geometrical and meteorological parameters are equally important for the determination of fluxes (e.g. plume height, wind direction, wind speed). A novel method to determine the wind speed by correlating measurement time series was implemented in the measurement routine, as well as the capability to determine the wind direction from the measurement itself.

To test the algorithms, measurements of NO₂ and SO₂ were performed at power plant stacks and at Mt. Etna in Sicily.