Submitted as: development and technical paper
10 Nov 2021
Submitted as: development and technical paper | 10 Nov 2021
Status: a revised version of this preprint is currently under review for the journal GMD.

Improved representation of the contemporary Greenland ice sheet firn layer by IMAU-FDM v1.2G

Max Brils, Peter Kuipers Munneke, Willem Jan van de Berg, and Michiel van den Broeke Max Brils et al.
  • Institute for Marine and Atmospheric Research, Utrecht University, Utrecht, the Netherlands

Abstract. The firn layer that covers 90 % of the Greenland ice sheet (GrIS) plays an important role in determining the response of the ice sheet to climate change. Meltwater can percolate into the firn layer and refreeze at greater depths, thereby temporarily preventing mass loss. However, as global warming leads to increasing surface melt, more surface melt may refreeze in the firn layer, thereby reducing the capacity to buffer subsequent episodes of melt. This can lead to a tipping point in meltwater runoff. It is therefore important to study the evolution of the Greenland firn layer in the past, present and future. In this study, we present the latest version of our firn model, IMAU-FDM (Firn Densification Model), with an application to the GrIS. We improved the density of freshly fallen snow, the dry-snow densification rate and the firn's thermal conductivity using recently published parameterizations and by calibrating to an extended set of observations of firn density, temperature and liquid water content at the GrIS. Overall, the updated model settings lead to higher firn air content and higher 10 m firn temperatures, owing to a lower density near the surface. The effect of the new model settings on the surface elevation change is investigated through three case studies located at Summit, KAN-U and FA-13. Most notably, the updated model shows greater inter- and intra-annual variability in elevation and an increased sensitivity to climate forcing.

Max Brils et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on gmd-2021-303', Baptiste Vandecrux, 01 Dec 2021
  • RC2: 'Comment on gmd-2021-303', Xavier Fettweis, 10 Dec 2021
  • RC3: 'Comment on gmd-2021-303', C. Max Stevens, 21 Dec 2021
  • AC1: 'Comment on gmd-2021-303', Max Brils, 17 Mar 2022

Max Brils et al.

Max Brils et al.


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Short summary
Firn covers the Greenland ice sheet (GrIS) and can temporarily prevent mass loss. Here, we present the latest version of our firn model, IMAU-FDM, with an application to the GrIS. We improved the density of fallen snow, the firn densification rate and its thermal conductivity. This leads to a higher air content and 10 m temperatures. Furthermore we investigate three case studies and find that the updated model shows greater variability and an increased sensitivity in surface elevation.