Preprints
https://doi.org/10.5194/egusphere-2022-693
https://doi.org/10.5194/egusphere-2022-693
10 Aug 2022
 | 10 Aug 2022

Reanalysis representation of low-level winds in the Antarctic near-coastal region

Thomas Caton Harrison, Stavroula Biri, Thomas J. Bracegirdle, John C. King, Elizabeth C. Kent, Étienne Vignon, and John Turner

Abstract. Low-level easterly winds encircling Antarctica help drive coastal currents which modify transport of circumpolar deep water to ice shelves, as well as the formation and distribution of sea ice. Reanalysis datasets are especially important at high southern latitudes where observations are few. Here, we investigate the representation of the mean state and short-term variability of coastal easterlies in three recent reanalyses, ERA5, MERRA-2 and JRA-55. Reanalysed winds are compared with summertime marine surface wind observations from the ASCAT scatterometer and surface and upper air measurements from coastal stations. Reanalysis coastal easterlies correlate highly with ASCAT (r=0.91, 0.89 and 0.85 for ERA5, MERRA-2 and JRA-55 respectively) but notable wind speed biases are found close to the coastal margins, especially near complex orography and at high wind speeds. To characterise short-term variability, 12-hourly reanalysis and coastal station winds are composited using self-organising maps (SOMs), which cluster timesteps under similar synoptic and mesoscale influences. Reanalysis performance is sensitive to the flow configuration at stations near steep coastal slopes, where they fail to capture the magnitude of surface wind speed variability when synoptic forcing is weak and conditions favour katabatic forcing. ERA5 exhibits the best overall performance, has more realistic orography and a more realistic jet structure and temperature profile. These results demonstrate the regime behaviour of Antarctica’s coastal winds and indicate important features of the coastal winds which are not well characterised by reanalysis datasets.

Journal article(s) based on this preprint

02 Dec 2022
Reanalysis representation of low-level winds in the Antarctic near-coastal region
Thomas Caton Harrison, Stavroula Biri, Thomas J. Bracegirdle, John C. King, Elizabeth C. Kent, Étienne Vignon, and John Turner
Weather Clim. Dynam., 3, 1415–1437, https://doi.org/10.5194/wcd-3-1415-2022,https://doi.org/10.5194/wcd-3-1415-2022, 2022
Short summary

Thomas Caton Harrison et al.

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-693', Anonymous Referee #1, 15 Sep 2022
  • RC2: 'Comment on egusphere-2022-693', Anonymous Referee #2, 16 Sep 2022
  • AC1: 'Comment on egusphere-2022-693', Thomas Caton Harrison, 20 Oct 2022

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-693', Anonymous Referee #1, 15 Sep 2022
  • RC2: 'Comment on egusphere-2022-693', Anonymous Referee #2, 16 Sep 2022
  • AC1: 'Comment on egusphere-2022-693', Thomas Caton Harrison, 20 Oct 2022

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by Thomas Caton Harrison on behalf of the Authors (25 Oct 2022)  Author's response   Author's tracked changes   Manuscript 
ED: Publish as is (26 Oct 2022) by Tiina Nygård
AR by Thomas Caton Harrison on behalf of the Authors (31 Oct 2022)

Journal article(s) based on this preprint

02 Dec 2022
Reanalysis representation of low-level winds in the Antarctic near-coastal region
Thomas Caton Harrison, Stavroula Biri, Thomas J. Bracegirdle, John C. King, Elizabeth C. Kent, Étienne Vignon, and John Turner
Weather Clim. Dynam., 3, 1415–1437, https://doi.org/10.5194/wcd-3-1415-2022,https://doi.org/10.5194/wcd-3-1415-2022, 2022
Short summary

Thomas Caton Harrison et al.

Thomas Caton Harrison et al.

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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.

Short summary
Easterly winds encircle Antarctica, moving sea ice and helping drive ocean currents which shield ice shelves from warmer waters. Our most complete picture of how these winds behave comes from reanalysis datasets. In this paper we use satellite data, surface measurements and weather balloons to test how realistic recent reanalysis estimates are. The winds are generally accurate, especially in the most recent of the datasets, but important short-term variations are often misrepresented.