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UP: Fachverband Umweltphysik

UP 4: Postersession

UP 4.12: Poster

Tuesday, February 26, 2013, 17:15–18:30, Poster EG

Temperature effects in MAX-DOAS observations of NO₂ — •Andreas Richter, Folkard Wittrock, Enno Peters, Anja Schönhardt, and John P. Burrows — Institute of Environmental Physics, University of Bremen, Bremen, Germany

Multi Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements are often applied to the observation of atmospheric NO₂. The method is based on absorption spectroscopy and uses the absorption cross-section of NO₂ to identify and quantify its amounts in the troposphere and stratosphere. As NO₂ has a temperature dependent absorption cross-section, atmospheric temperature impacts on the observed signal.

In this study, the effects of the temperature dependence of the NO2 absorption cross-section on MAX-DOAS measurements of stratospheric and tropospheric NO₂ are discussed and the errors introduced by current retrieval approaches are discussed.

Using data from the CINDI campaign, it is then investigated in how far the temperature dependence of the NO₂ signal can be exploited to derive a tropospheric NO₂ column from zenith-sky observations alone, and the results are compared to those obtained from off-axis measurements.

Based on a similar approach, the applicability of the temperature signal for correction of stratospheric observations in polluted places such as Bremen is evaluated by applying a modified Langley Plot method to zenith-sky observations at twilight.