SMuK 2021 – wissenschaftliches Programm
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UP: Fachverband Umweltphysik
UP 2: Clouds and Aerosols
UP 2.6: Vortrag
Donnerstag, 2. September 2021, 15:25–15:40, H3
Occurrence of Polar Stratospheric Clouds as derived from ground-based zenith DOAS observations — •Bianca Lauster1,2, Steffen Dörner1, Udo Frieß2, Myojeong Gu1, Janis Pukite1, and Thomas Wagner1 — 1Max Planck Institute for Chemistry, Mainz, Germany — 2Institute of Environmental Physics, University Heidelberg, Heidelberg, Germany
Polar Stratospheric Clouds (PSCs) are an important component of ozone depletion in the polar stratosphere. Although satellite observations already yield high spatial coverage, continuous ground-based measurements with high temporal resolution can be a valuable complement. Since 1999, a MAX-DOAS (Multi AXis-Differential Optical Absorption Spectroscopy) instrument has been operating at the German research station Neumayer (70° S, 8° W), Antarctica. Although typically used to retrieve slant column densities of trace gases such as BrO or OClO, this study investigates the so-called colour index (CI). Defined as the ratio between the observed intensities of scattered sun light at two wavelengths, it enables to monitor the occurrence of PSCs during twilight even in the presence of tropospheric clouds. Using the radiative transfer model McArtim, the analysis of CI variations with solar zenith angle enables the detection of PSCs. Here, it is advantageous that measurements are available in the UV and visible spectral range which allows a more extensive comparison of the wavelength choice. The aim is to improve and evaluate the potential of this method. It is then used to infer the occurrence of PSCs throughout the measurement time series of more than 20 years.