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UP: Fachverband Umweltphysik

UP 2: Trace Gases

UP 2.6: Vortrag

Mittwoch, 16. März 2011, 11:15–11:30, HSZ 201

MAX-DOAS aerosol and trace gases measurements in megacities in China — •Xin Li^1,2, Theo Brauers¹, and Min Shao² — ¹Institut für Energie- und Klimaforschung (IEK-8: Troposphäre), Forschungszentrum Jülich, Jülich, D — ²College of Environmental Science and Engineering Peking University, Beijing, P. R. China

Multi Axis Differential Optical Absorption Spectroscopy (MAXDOAS) is a new remote sensing technique to measure atmospheric trace gases. Compared to other areas in the world, the atmospheric observations in megacities in China are rather limited. We present MAX-DOAS measurements at four sites in Beijing and Guangzhou in 2006 and 2008. At each site, the scattered sunlight was recorded at 7 elevation angles for about 1 months. Using the zenith spectrum as reference, the Differential Slant Column Densities (DSCDs) of HCHO, CHOCHO, O₄ and NO₂ at offaxis viewing geometries were derived from the DOAS fit. These DSCDs were simulated using a backward Monte Carlo radiative transfer model. The aerosol and trace gas profiles were defined by 3 parameters: the integrated quantities (T), the height of the surface layer (H), and the fraction of T below H. We fitted the modeled values to the measured values at the corresponding viewing geometries by varying the 3 parameters. The aerosol extinction and the boundary layer height were successfully retrieved from the measured O₄ DSCDs as well as ground level concentrations of CHOCHO, HCHO, and NO₂, the latter being compared to simultaneous in-situ measurements.