A global climatology of polar lows investigated for local differences and wind-shear environments
- Department of Physics and Technology, Arctic University of Norway, Tromsø, Norway
- Department of Physics and Technology, Arctic University of Norway, Tromsø, Norway
Abstract. Polar lows are intense mesoscale cyclones developing in marine polar air masses. This study presents a new global climatology of polar lows based on the ERA-5 reanalysis for the years 1979–2020. Criteria for the detection of polar lows are derived based on a comparison of six polar-low archives with cyclones derived by a mesoscale tracking algorithm. The characteristics associated with polar lows are considered by the criteria: (i) intense cyclone: large relative vorticity, (ii) mesoscale: small vortex diameter, and (iii) development in the marine polar air masses: combination of low dry-static stability and low potential temperature at the tropopause.
Polar lows develop in all marine areas adjacent to sea ice or cold landmasses, mainly in the winter half-year. The length and intensity of the season are regionally dependent. The highest density appears in the Nordic Seas. For all ocean sub-basins, forward-shear polar lows are the most common, whereas weak shear and those propagating towards warmer environments are second and third most frequent, depending on the area. Reverse-shear polar lows and those propagating towards colder environments are rather seldom, especially in the Southern Ocean. Generally, PLs share many characteristics across ocean basins and wind-shear categories. The most remarkable difference is that forward-shear polar lows are often occurring in stronger vertical wind shear, whereas reverse-shear polar lows feature lower static stability. Hence, the contribution to a fast baroclinic growth rate is slightly different for the shear categories.
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Notice on discussion status
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Preprint
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
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Supplement
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Journal article(s) based on this preprint
Patrick Johannes Stoll
Interactive discussion
Status: closed
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RC1: 'Comment on wcd-2021-60', Anonymous Referee #1, 26 Oct 2021
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AC1: 'See the attached document', Patrick Stoll, 12 Jan 2022
The comment was uploaded in the form of a supplement: https://wcd.copernicus.org/preprints/wcd-2021-60/wcd-2021-60-AC1-supplement.pdf
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AC1: 'See the attached document', Patrick Stoll, 12 Jan 2022
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RC2: 'Comment on wcd-2021-60', Anonymous Referee #2, 26 Nov 2021
My comments are in the attached file. Please find it.
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AC2: 'See the attached document', Patrick Stoll, 12 Jan 2022
The comment was uploaded in the form of a supplement: https://wcd.copernicus.org/preprints/wcd-2021-60/wcd-2021-60-AC2-supplement.pdf
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AC2: 'See the attached document', Patrick Stoll, 12 Jan 2022
Peer review completion
Interactive discussion
Status: closed
-
RC1: 'Comment on wcd-2021-60', Anonymous Referee #1, 26 Oct 2021
-
AC1: 'See the attached document', Patrick Stoll, 12 Jan 2022
The comment was uploaded in the form of a supplement: https://wcd.copernicus.org/preprints/wcd-2021-60/wcd-2021-60-AC1-supplement.pdf
-
AC1: 'See the attached document', Patrick Stoll, 12 Jan 2022
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RC2: 'Comment on wcd-2021-60', Anonymous Referee #2, 26 Nov 2021
My comments are in the attached file. Please find it.
-
AC2: 'See the attached document', Patrick Stoll, 12 Jan 2022
The comment was uploaded in the form of a supplement: https://wcd.copernicus.org/preprints/wcd-2021-60/wcd-2021-60-AC2-supplement.pdf
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AC2: 'See the attached document', Patrick Stoll, 12 Jan 2022
Peer review completion
Journal article(s) based on this preprint
Patrick Johannes Stoll
Patrick Johannes Stoll
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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