Preprints
https://doi.org/10.5194/tc-2021-150
https://doi.org/10.5194/tc-2021-150

  02 Jun 2021

02 Jun 2021

Review status: a revised version of this preprint was accepted for the journal TC and is expected to appear here in due course.

Relating snowfall observations to Greenland ice sheet mass changes: an atmospheric circulation perspective

Michael Gallagher1,2, Matthew Shupe1,2, Hélène Chepfer3,4, and Tristan L'Ecuyer5 Michael Gallagher et al.
  • 1Cooperative Institute for Research in Environmental Science, Boulder, Colorado, USA
  • 2NOAA/Physical Sciences Laboratory, Boulder, Colorado, USA
  • 3LMD/IPSL, Sorbonne Université, Paris, France
  • 4LMD/IPSL, CNRS, Ecole Polytechnique, Palaiseau, France
  • 5Department of Atmospheric and Oceanic Sciences, University of Wisconsin-Madison, Madison, WI, USA

Abstract. Snowfall is the major source of mass for the Greenland ice sheet but the spatial and temporal variability of its contributions to mass balance have so far been inadequately quantified. By characterizing local atmospheric circulation and utilizing CloudSat spaceborne radar observations of snowfall, we provide a detailed spatial analysis of snowfall variability and its relationship to Greenland mass balance, presenting first-of-their-kind daily maps of the spatial variability in snowfall from observations across Greenland. For identified regional atmospheric circulation patterns, we show that the spatial distribution and net mass input of snowfall varies significantly with the position and strength of surface cyclones. Cyclones west of Greenland driving southerly flow contribute significantly more snowfall than any other circulation regime, with each daily occurrence of the most extreme southerly circulation pattern is contributes an average of 1.66 Gt of snow to the Greenland ice sheet. While cyclones east of Greenland, patterns with the least snowfall, contribute as little as 0.58 Gt each day. Above 2 km on the ice sheet where snowfall is inconsistent, extreme southerly patterns are the most significant mass contributors, with up to 1.20 Gt of snowfall above this elevation. This analysis demonstrates that snowfall over the interior of Greenland varies by up to a factor of five depending on regional circulation conditions. Using independent observations of mass changes made by the Gravity Recovery and Climate Experiment (GRACE), we verify that the largest mass increases are tied to the southerly regime with cyclones west of Greenland. For occurrences of the strongest southerly pattern, GRACE indicates a net mass increase of 1.29 Gt in the ice sheet accumulation zone (above 2 km elevation) compared to the 1.20 Gt of snowfall observed by CloudSat. This good overall agreement suggests that the analytical approach presented here can be used to directly quantify snowfall mass contributions and their most significant drivers spatially across the GrIS. While previous research has implicated this same southerly regime in ablation processes during summer, this paper shows that ablation mass loss in this circulation regime is nearly an order of magnitude larger than the mass gain from associated snowfall. For daily occurrences of the southerly circulation regime, a mass loss of approximately 11 Gt is observed across the ice sheet despite snowfall mass input exceeding one gigatonne. By analyzing the spatial variability of snowfall and mass changes, this research provides new insight into connections between regional atmospheric circulation and GrIS mass balance.

Michael Gallagher et al.

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on tc-2021-150', Anonymous Referee #1, 02 Jul 2021
    • AC1: 'Reply on RC1', Michael Gallagher, 15 Sep 2021
  • RC2: 'Comment on tc-2021-150', Anonymous Referee #2, 03 Jul 2021
    • AC2: 'Reply on RC2', Michael Gallagher, 15 Sep 2021
  • AC3: 'Comment on tc-2021-150', Michael Gallagher, 15 Sep 2021

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on tc-2021-150', Anonymous Referee #1, 02 Jul 2021
    • AC1: 'Reply on RC1', Michael Gallagher, 15 Sep 2021
  • RC2: 'Comment on tc-2021-150', Anonymous Referee #2, 03 Jul 2021
    • AC2: 'Reply on RC2', Michael Gallagher, 15 Sep 2021
  • AC3: 'Comment on tc-2021-150', Michael Gallagher, 15 Sep 2021

Michael Gallagher et al.

Michael Gallagher et al.

Viewed

Total article views: 579 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
377 150 52 579 7 7
  • HTML: 377
  • PDF: 150
  • XML: 52
  • Total: 579
  • BibTeX: 7
  • EndNote: 7
Views and downloads (calculated since 02 Jun 2021)
Cumulative views and downloads (calculated since 02 Jun 2021)

Viewed (geographical distribution)

Total article views: 577 (including HTML, PDF, and XML) Thereof 577 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 02 Dec 2021
Download
Short summary
By using direct observations of snowfall and mass changes, the variability of daily snowfall mass input to the Greenland ice sheet is quantified for the first time. With new methods we conclude that cyclones west of Greenland in summer contribute the most snowfall, with 1.66 Gt per occurrence. These cyclones are contextualized in the broader Greenland climate and snowfall is validated against mass changes to verify the results. Snowfall and mass change observations are shown to agree well.