Occurrence of Polar Stratospheric Clouds as derived from Ground-based Zenith DOAS Observations using the Colour Index
Polar stratospheric clouds (PSCs) are an important component of ozone chemistry in polar regions. Studying the ozone-depleting processes requires a precise description of PSCs on a long-term basis. Although satellite observations already yield high spatial coverage, continuous ground-based measureme...
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ftcopernicus:oai:publications.copernicus.org:acpd106374 2023-05-15T13:38:41+02:00 Occurrence of Polar Stratospheric Clouds as derived from Ground-based Zenith DOAS Observations using the Colour Index Lauster, Bianca Dörner, Steffen Enell, Carl-Fredrik Frieß, Udo Gu, Myojeong Pukīte, Janis Raffalski, Uwe Wagner, Thomas 2022-09-23 application/pdf https://doi.org/10.5194/acp-2022-647 https://acp.copernicus.org/preprints/acp-2022-647/ eng eng doi:10.5194/acp-2022-647 https://acp.copernicus.org/preprints/acp-2022-647/ eISSN: 1680-7324 Text 2022 ftcopernicus https://doi.org/10.5194/acp-2022-647 2022-09-26T16:22:41Z Polar stratospheric clouds (PSCs) are an important component of ozone chemistry in polar regions. Studying the ozone-depleting processes requires a precise description of PSCs on a long-term basis. Although satellite observations already yield high spatial coverage, continuous ground-based measurements covering long time periods can be a valuable complement. In this study, differential optical absorption spectroscopy (DOAS) instruments are used to investigate the occurrence of PSCs based on the so-called colour index (CI), i.e. the colour of the zenith sky. Defined as the ratio between the observed intensities of scattered sunlight at two wavelengths, it provides a method to detect PSCs during twilight even in the presence of tropospheric clouds. We present data from instruments at the German research station Neumayer, Antarctica (71 °S, 8 °W) as well as Kiruna, Sweden (68 °N, 20 °E), which are in operation for more than 20 years. For a comprehensive interpretation of the measurement data, the well-established radiative transfer model McArtim is used and radiances of scattered sunlight are simulated at several wavelengths for different solar zenith angles and various atmospheric conditions. The aim is to improve and evaluate the potential of this method. It is then used to infer the seasonal cycle and the variability of PSC occurrence throughout the time series measured in both hemispheres. A good agreement is found to satellite retrievals with deviations particularly in spring. The unexpectedly high signal observed in the DOAS data during spring time suggests the influence of volcanic aerosol. This is also indicated by enhanced aerosol extinction as seen from OMPS data but is not captured by other PSC climatologies. The presented approach allows the detection of PSCs for various atmospheric conditions not only for individual case studies but over entire time series, which is a decisive advance compared to previous work on the PSC detection from ground-based instruments. Apart from the interannual variability, ... Text Antarc* Antarctica Kiruna Copernicus Publications: E-Journals Kiruna Neumayer |
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Open Polar |
collection |
Copernicus Publications: E-Journals |
op_collection_id |
ftcopernicus |
language |
English |
description |
Polar stratospheric clouds (PSCs) are an important component of ozone chemistry in polar regions. Studying the ozone-depleting processes requires a precise description of PSCs on a long-term basis. Although satellite observations already yield high spatial coverage, continuous ground-based measurements covering long time periods can be a valuable complement. In this study, differential optical absorption spectroscopy (DOAS) instruments are used to investigate the occurrence of PSCs based on the so-called colour index (CI), i.e. the colour of the zenith sky. Defined as the ratio between the observed intensities of scattered sunlight at two wavelengths, it provides a method to detect PSCs during twilight even in the presence of tropospheric clouds. We present data from instruments at the German research station Neumayer, Antarctica (71 °S, 8 °W) as well as Kiruna, Sweden (68 °N, 20 °E), which are in operation for more than 20 years. For a comprehensive interpretation of the measurement data, the well-established radiative transfer model McArtim is used and radiances of scattered sunlight are simulated at several wavelengths for different solar zenith angles and various atmospheric conditions. The aim is to improve and evaluate the potential of this method. It is then used to infer the seasonal cycle and the variability of PSC occurrence throughout the time series measured in both hemispheres. A good agreement is found to satellite retrievals with deviations particularly in spring. The unexpectedly high signal observed in the DOAS data during spring time suggests the influence of volcanic aerosol. This is also indicated by enhanced aerosol extinction as seen from OMPS data but is not captured by other PSC climatologies. The presented approach allows the detection of PSCs for various atmospheric conditions not only for individual case studies but over entire time series, which is a decisive advance compared to previous work on the PSC detection from ground-based instruments. Apart from the interannual variability, ... |
format |
Text |
author |
Lauster, Bianca Dörner, Steffen Enell, Carl-Fredrik Frieß, Udo Gu, Myojeong Pukīte, Janis Raffalski, Uwe Wagner, Thomas |
spellingShingle |
Lauster, Bianca Dörner, Steffen Enell, Carl-Fredrik Frieß, Udo Gu, Myojeong Pukīte, Janis Raffalski, Uwe Wagner, Thomas Occurrence of Polar Stratospheric Clouds as derived from Ground-based Zenith DOAS Observations using the Colour Index |
author_facet |
Lauster, Bianca Dörner, Steffen Enell, Carl-Fredrik Frieß, Udo Gu, Myojeong Pukīte, Janis Raffalski, Uwe Wagner, Thomas |
author_sort |
Lauster, Bianca |
title |
Occurrence of Polar Stratospheric Clouds as derived from Ground-based Zenith DOAS Observations using the Colour Index |
title_short |
Occurrence of Polar Stratospheric Clouds as derived from Ground-based Zenith DOAS Observations using the Colour Index |
title_full |
Occurrence of Polar Stratospheric Clouds as derived from Ground-based Zenith DOAS Observations using the Colour Index |
title_fullStr |
Occurrence of Polar Stratospheric Clouds as derived from Ground-based Zenith DOAS Observations using the Colour Index |
title_full_unstemmed |
Occurrence of Polar Stratospheric Clouds as derived from Ground-based Zenith DOAS Observations using the Colour Index |
title_sort |
occurrence of polar stratospheric clouds as derived from ground-based zenith doas observations using the colour index |
publishDate |
2022 |
url |
https://doi.org/10.5194/acp-2022-647 https://acp.copernicus.org/preprints/acp-2022-647/ |
geographic |
Kiruna Neumayer |
geographic_facet |
Kiruna Neumayer |
genre |
Antarc* Antarctica Kiruna |
genre_facet |
Antarc* Antarctica Kiruna |
op_source |
eISSN: 1680-7324 |
op_relation |
doi:10.5194/acp-2022-647 https://acp.copernicus.org/preprints/acp-2022-647/ |
op_doi |
https://doi.org/10.5194/acp-2022-647 |
_version_ |
1766109566834049024 |