Hannover 2010 – scientific programme

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UP: Fachverband Umweltphysik

UP 2: Poster Session

UP 2.9: Poster

Tuesday, March 9, 2010, 16:30–18:30, Lichthof

Different wavelength evaluation ranges in the retrieval of trace gases with DOAS at the example of BrO — •Leif Vogel¹, Holger Sihler^1,2, Johannes Lampel¹, Ulrich Platt¹, and Thomas Wagner² — ¹Institut für Umweltphysik, Universität Heidelberg — ²MPI für Chemie, Mainz

Optical remote sensing via scattered sunlight Differential Optical Absorption Spectroscopy (DOAS) is routinely used to determine various trace gases in the atmosphere. Different applications and platforms (e.g. DOAS of volcanic plumes, Satellite measurements, Zenith DOAS or Max-DOAS) differ in measurement conditions, cross correlations of absorptions of different trace gases and their respective concentrations. Here, we present a method to determine the optimal evaluation range at the example of Bromine Oxide (BrO).

With strongest absorption features of BrO between 315nm - 360nm, its retrieval results can depend on cross correlations with strong absorber like Ozone (O₃) or sulfur dioxide (SO₂). Whereas O₃ influences especially Satellite and stratospheric measurements, SO₂ cannot be neglected in the case of high volcanic gas emissions. Absorption features of both species are most pronounced at low wavelengths, but their diminished influence at higher wavelength ranges competes with a higher detection limit of BrO. The study is performed with artificial spectra and the results are compared with retrievals from real spectra of volcanic plumes, satellite and marine Max-DOAS measurements.