Mapping the aerodynamic roughness of the Greenland ice sheet surface using ICESat-2
- 1Institute for Marine and Atmospheric Research (IMAU), Utrecht University, Utrecht, the Netherlands (m.vantiggelen@uu.nl)
- 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
The roughness of a natural surface is an important parameter in atmospheric models, as it 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 take advantage of the measurements of the ICESat-2 satellite laser altimeter. We use the geolocated photons product (ATL03) to retrieve a 1-m resolution surface elevation product over the K-transect (West Greenland ice sheet). In combination with a bulk drag partitioning model, the retrieved surface elevation is used to estimate the aerodynamic roughness length (z0m) of the surface.
We demonstrate the high precision of the retrieved ICESat-2 elevation using co-located UAV photogrammetry, and then evaluate the modelled aerodynamic roughness against multiple in situ eddy-covariance observations. The results point out the importance to use a bulk drag model over a more empirical formulation.
The currently available ATL03 geolocated photons are used to map the aerodynamic roughness along the K-transect (2018-2020). We find a considerable spatiotemporal variability in z0m, ranging between 10−4 m for a smooth snow surface to more than 10−1 m for rough crevassed areas, which confirms the need to incorporate a variable aerodynamic roughness in atmospheric models over ice sheets.
How to cite: van Tiggelen, M., Smeets, P. C. J. P., Reijmer, C. H., Wouters, B., Steiner, J. F., Nieuwstraten, E. J., Immerzeel, W. W., and van den Broeke, M. R.: Mapping the aerodynamic roughness of the Greenland ice sheet surface using ICESat-2, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2136, https://doi.org/10.5194/egusphere-egu21-2136, 2021.