EGU21-5385, updated on 04 Mar 2021
https://doi.org/10.5194/egusphere-egu21-5385
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Occurrence of Polar Stratospheric Clouds using ground-based DOAS observations

Bianca Lauster1, Steffen Dörner1, Udo Frieß2, Myojeong Gu1, Janis Pukite1, and Thomas Wagner1
Bianca Lauster et al.
  • 1Max Planck Institute for Chemistry, Satellite Remote Sensing, Mainz, Germany (b.lauster@mpic.de)
  • 2Institute of Environmental Physics, University of Heidelberg, Heidelberg, Germany

Polar Stratospheric Clouds (PSCs) favour heterogeneous reactions and thus are an important component of ozone depletion processes in polar regions. Although satellite observations already yield high spatial coverage, the sampling frequency of a specific air volume depends on the measurement method. Here, 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. Primarily, slant column densities of trace gases such as NO2, BrO and OClO are retrieved. However, in this study the so-called colour index (CI), i.e. the colour of the zenith sky, is investigated. Defined as the ratio between the observed intensities of scattered sun light at two wavelengths, it enables to monitor the occurrence of polar stratospheric clouds during twilight even in the presence of tropospheric clouds.

Using the radiative transfer model McArtim, the CI changes in the presence of polar stratospheric clouds can be analysed. Especially the height of the PSC layer affects the retrieved signal, but also the choice of the wavelengths has a strong impact. Here, it is advantageous that measurements are available in the UV and visible spectral range which allows a more extensive comparison of different CI choices. In order to assess the application of the colour index method, meteorological data are used to identify PSC cases in the data set.

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.

How to cite: Lauster, B., Dörner, S., Frieß, U., Gu, M., Pukite, J., and Wagner, T.: Occurrence of Polar Stratospheric Clouds using ground-based DOAS observations, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5385, https://doi.org/10.5194/egusphere-egu21-5385, 2021.

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