Preprints
https://doi.org/10.5194/egusphere-2023-1041
https://doi.org/10.5194/egusphere-2023-1041
09 Jun 2023
 | 09 Jun 2023

Evaporative controls on Antarctic precipitation: An ECHAM6 model study using novel water tracer diagnostics

Qinggang Gao, Louise C. Sime, Alison McLaren, Thomas J. Bracegirdle, Emilie Capron, Rachael H. Rhodes, Hans Christian Steen-Larsen, Xiaoxu Shi, and Martin Werner

Abstract. Improving our understanding of the controls on Antarctic precipitation is critical for gaining insights into polar, and global changes. Here we develop and implement innovative water tracing diagnostics in the atmospheric general circulation model ECHAM6. These tracers provide new precise information on moisture source locations and properties of Antarctic precipitation. In our preindustrial simulation, annual mean Antarctic precipitation originating from the open ocean has a source latitude range of 49–35° S; a source sea surface temperature range of 9.8–16.3 °C; a source 2 m relative humidity range of 75.6–83.3 %; and a source 10 m wind speed (wind10) range of 10.1 to 11.3 m s-1. The tendency of poleward vapour transport to follow moist isentropes means that central Antarctic precipitation is sourced from more equatorward (distant) sources via elevated transport pathways than coastal Antarctic precipitation. We find however this tendency breaks down in the lower troposphere, likely due to diabatic cooling. Heavy precipitation is sourced by longer-range moisture transport: it comes from 2.9° (300 km, averaged over Antarctica) more equatorward (distant) sources compared to the rest of precipitation. Precipitation during negative phases of the Southern Annular Mode (SAM) also comes from more equatorward moisture sources (by 2.4°, averaged over Antarctica) than precipitation during positive SAM phases, likely due to amplified planetary waves during negative SAM phases. Moreover, source wind10 of annual mean precipitation is on average 2.1 m s-1 higher than annual mean wind10 at the evaporation source locations from which the precipitation originates. This shows that the evaporation of moisture driving Antarctic precipitation occurs under windier conditions than average. This is the first time this particular thermodynamic control of Southern Ocean surface wind on moisture availability for Antarctic precipitation has been quantified. Overall, our novel water tracing diagnostics enhance our understanding of the controlling factors of Antarctic precipitation.

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Journal article(s) based on this preprint

13 Feb 2024
Evaporative controls on Antarctic precipitation: an ECHAM6 model study using innovative water tracer diagnostics
Qinggang Gao, Louise C. Sime, Alison J. McLaren, Thomas J. Bracegirdle, Emilie Capron, Rachael H. Rhodes, Hans Christian Steen-Larsen, Xiaoxu Shi, and Martin Werner
The Cryosphere, 18, 683–703, https://doi.org/10.5194/tc-18-683-2024,https://doi.org/10.5194/tc-18-683-2024, 2024
Short summary
Qinggang Gao, Louise C. Sime, Alison McLaren, Thomas J. Bracegirdle, Emilie Capron, Rachael H. Rhodes, Hans Christian Steen-Larsen, Xiaoxu Shi, and Martin Werner

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1041', Anonymous Referee #1, 06 Sep 2023
    • AC1: 'Reply on RC1', Qinggang Gao, 23 Oct 2023
  • RC2: 'Comment on egusphere-2023-1041', Anonymous Referee #2, 15 Sep 2023
    • AC2: 'Reply on RC2', Qinggang Gao, 23 Oct 2023

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1041', Anonymous Referee #1, 06 Sep 2023
    • AC1: 'Reply on RC1', Qinggang Gao, 23 Oct 2023
  • RC2: 'Comment on egusphere-2023-1041', Anonymous Referee #2, 15 Sep 2023
    • AC2: 'Reply on RC2', Qinggang Gao, 23 Oct 2023

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
ED: Reconsider after major revisions (further review by editor and referees) (27 Oct 2023) by Thomas Mölg
AR by Qinggang Gao on behalf of the Authors (27 Oct 2023)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (06 Nov 2023) by Thomas Mölg
RR by Anonymous Referee #2 (28 Nov 2023)
ED: Publish subject to minor revisions (review by editor) (29 Nov 2023) by Thomas Mölg
AR by Qinggang Gao on behalf of the Authors (09 Dec 2023)  Author's response   Author's tracked changes   Manuscript 
ED: Publish as is (18 Dec 2023) by Thomas Mölg
AR by Qinggang Gao on behalf of the Authors (19 Dec 2023)

Journal article(s) based on this preprint

13 Feb 2024
Evaporative controls on Antarctic precipitation: an ECHAM6 model study using innovative water tracer diagnostics
Qinggang Gao, Louise C. Sime, Alison J. McLaren, Thomas J. Bracegirdle, Emilie Capron, Rachael H. Rhodes, Hans Christian Steen-Larsen, Xiaoxu Shi, and Martin Werner
The Cryosphere, 18, 683–703, https://doi.org/10.5194/tc-18-683-2024,https://doi.org/10.5194/tc-18-683-2024, 2024
Short summary
Qinggang Gao, Louise C. Sime, Alison McLaren, Thomas J. Bracegirdle, Emilie Capron, Rachael H. Rhodes, Hans Christian Steen-Larsen, Xiaoxu Shi, and Martin Werner
Qinggang Gao, Louise C. Sime, Alison McLaren, Thomas J. Bracegirdle, Emilie Capron, Rachael H. Rhodes, Hans Christian Steen-Larsen, Xiaoxu Shi, and Martin Werner

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Latest update: 18 Sep 2024
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Short summary
Antarctic precipitation is a crucial component of the climate system. Its spatio-temporal variability impacts sea level changes and the interpretation of water isotope measurements in ice cores. To better understand its climatic drivers, we developed water tracers in an atmospheric model to identify moisture source conditions from which precipitation originates. We find that mid-latitude surface winds exert an important control on moisture availability for Antarctic precipitation.