Preprints
https://doi.org/10.5194/tc-2020-378
https://doi.org/10.5194/tc-2020-378

  08 Jan 2021

08 Jan 2021

Review status: a revised version of this preprint is currently under review for the journal TC.

Mapping the aerodynamic roughness of the Greenland ice sheet surface using ICESat-2: Evaluation over the K-transect

Maurice van Tiggelen1, Paul C. J. P. Smeets1, Carleen H. Reijmer1, Bert Wouters1,3, Jakob F. Steiner2,4, Emile J. Nieuwstraten2, Walter W. Immerzeel2, and Michiel R. van den Broeke1 Maurice van Tiggelen et al.
  • 1Institute for Marine and Atmospheric research (IMAU), Utrecht University, Utrecht, the Netherlands
  • 2Department of Physical Geography, Utrecht University, Utrecht, the Netherlands
  • 3Department of Geoscience and Remote Sensing, Delft University of Technology, Delft, the Netherlands
  • 4International Centre for Integrated Mountain Development, Kathmandu, Nepal

Abstract. The aerodynamic roughness of heat, moisture and momentum of a natural surface is an important parameter in atmospheric models, as it co-determines the intensity of turbulent transfer between the atmosphere and the surface. Unfortunately this parameter is often poorly known, especially in remote areas where neither high-resolution elevation models nor eddy-covariance measurements are available. In this study we adapt a bulk drag partitioning model to estimate the aerodynamic roughness length (z0m) such that it can be applied to 1D (i.e. unidirectional) elevation profiles, typically measured by laser altimeters. We apply the model to a rough ice surface on the K-transect (western Greenland ice sheet) using UAV photogrammetry, and evaluate the modelled roughness against in situ eddy-covariance observations. We then present a method to estimate the topography at 1 m horizontal resolution using the ICESat-2 satellite laser altimeter, and demonstrate the high precision of the satellite elevation profiles against UAV photogrammetry. The currently available satellite profiles are used to map the aerodynamic roughness during different time periods along the K-transect, that is compared to an extensive dataset of in situ observations. We find a considerable spatiotemporal variability in z0m, ranging between 10−4 m for a smooth snow surface over 10−1 m for rough crevassed areas, which confirms the need to incorporate a variable aerodynamic roughness in atmospheric models over ice sheets.

Maurice van Tiggelen et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on tc-2020-378', Ute Herzfeld, 21 Jan 2021
    • AC1: 'Reply on CC1', Maurice Van Tiggelen, 01 Apr 2021
  • CC2: 'Comment on tc-2020-378', Ute Herzfeld, 21 Jan 2021
  • RC1: 'Comment on tc-2020-378', Christof Lüpkes, 01 Feb 2021
    • AC2: 'Reply on RC1', Maurice Van Tiggelen, 01 Apr 2021
  • RC2: 'Comment on tc-2020-378', Anonymous Referee #2, 11 Feb 2021
    • AC3: 'Reply on RC2', Maurice Van Tiggelen, 01 Apr 2021
  • RC3: 'Comment on tc-2020-378', Shane Grigsby, 21 Feb 2021
    • AC4: 'Reply on RC3', Maurice Van Tiggelen, 01 Apr 2021

Maurice van Tiggelen et al.

Data sets

Dataset for figures Maurice van Tiggelen, Paul C. J. P. Smeets, Carleen H. Reijmer, Bert Wouters, Jakob F. Steiner, Emile J. Nieuwstraten, Walter W. Immerzeel, and Michiel R. van den Broeke https://doi.org/10.5281/zenodo.4386867

Maurice van Tiggelen et al.

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Latest update: 20 Apr 2021
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Short summary
We developed a method to estimate the aerodynamic properties of the Greenland ice sheet surface using either UAV or satellite remote sensing. We show that this new method is able to reproduce the important spatiotemporal variability in surface aerodynamic roughness, measured by the field observations. The new maps of surface roughness can be used in atmospheric models to improve simulations of surface turbulent heat fluxes, therefore surface energy-and-mass balance over rough ice worldwide.