Preprints
https://doi.org/10.5194/tc-2021-379
https://doi.org/10.5194/tc-2021-379
18 Jan 2022
 | 18 Jan 2022
Status: a revised version of this preprint was accepted for the journal TC and is expected to appear here in due course.

How does a change in climate variability impact the Greenland ice-sheet surface mass balance?

Tobias Zolles and Andreas Born

Abstract. The future of the Greenland ice-sheet largely depends on the changing climate. When ice-sheet models are run for time periods that extend far beyond the observational record they are often forced by climatology instead of a transient climate. We investigate how this simplification impacts the surface mass balance using the Bergen Snow Simulator. The model was run for up to 500 years using the same atmospheric climatology, but different variability, as forcing. We achieve this by re-arranging the years in the ERA-interim reanalysis while leaving the intra-annual variations unchanged. This changes the surface mass balance by less than 5 % over the entire Greenland ice sheet.

However, using daily averages as forcing introduces large changes in intra-annual variability and thereby overestimates the Greenland-wide surface mass balance by 40 %. The biggest contributor is precipitation followed by temperature. The most important process is that small amounts of snowfall from the daily climatology overestimate the albedo, leading to an increased SMB. We propose a correction that distributes the monthly precipitation over a realistic intra-monthly variability. This approach reduces the SMB overestimation to 15–25 %. We conclude that simulations of the Greenland surface mass and energy balance should be forced with a transient climate. Particular care must be taken if only climatological data is available for simulations with a model that was calibrated with transient data. If daily transient data cannot be used, at least the precipitation should follow a natural daily distribution.

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Tobias Zolles and Andreas Born

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Review of Zolles and Born', Anonymous Referee #1, 04 Mar 2022
  • RC2: 'Comment on tc-2021-379', Anonymous Referee #2, 06 May 2022

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Review of Zolles and Born', Anonymous Referee #1, 04 Mar 2022
  • RC2: 'Comment on tc-2021-379', Anonymous Referee #2, 06 May 2022
Tobias Zolles and Andreas Born
Tobias Zolles and Andreas Born

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Latest update: 15 Jun 2024
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Short summary
The Greenland ice-sheet largely depends on the climate state. The uncertainties associated with the year-to-year variability have only a marginal impact on our simulated surface mass budget, this increases our confidence in projections and reconstructions. Basing the simulations based on proxies for, f.ex., temperature, overestimates the surface mass balance, as climatologies lead to small amounts of snowfall every day. This can be reduced by including sub-monthly precipitation variability.