A note on digital elevation model smoothing and driving stresses
Abstract
Ice-flow fields, including the driving stress, provide important information on the current state and evolution of Antarctic and Greenland ice-sheet dynamics. However, computation of flow fields from continent-scale DEMs requires the use of smoothing functions and scales, the choice of which can be ad hoc. This study evaluates smoothing functions and scales for robust calculations of driving stress from Antarctic DEMs. Our approach compares a variety of filters and scales for their capacity to minimize the residual between predicted and observed flow direction fields. We find that a spatially varying triangular filter with a width of 8–10 ice thicknesses provides the closest match between the observed and predicted flow direction fields. We use the predicted flow direction fields to highlight artefacts in observed Antarctic velocities, demonstrating that comparison of multiple observational data sets has utility for quality control of continent-scale data sets.
Downloads
References
Bamber J., Gomez-Dans J. & Griggs J. 2009. A new 1 km digital elevation model of the Antarctic derived from combined satellite radar and laser data—part 1: data and methods. The Cryosphere 3, 101–111, https://doi.org/10.5194/tc-3-101-2009.
Brinkerhoff D. & Johnson J. 2015. A stabilized finite element method for calculating balance velocities in ice sheets. Geoscientific Model Development 8, 1275–1283, https://doi.org/10.5194/gmd-8-1275-2015.
Budd W. & Warner R. 1996. A computer scheme for rapid calculations of balance–flux distributions. Annals of Glaciology 23, 21–27, https://doi.org/10.1017/S0260305500013215
Fretwell P., Pritchard H.D, Vaughan D.G., Bamber J.L., Barrand N.E., Bell R., Bianchi C., Bingham R.G., Blankenship D.D., Casassa G., Catania G., Callens D., Conway H., Cook A.J., Corr H.F.J., Damaske D., Damm V., Ferraccioli F., Forsberg R., Fujita S., Gim Y., Gogineni P., Griggs J.A., Hindmarsh R.C.A., Holmlund P., Holt J.W., Jacobel R.W., Jenkins A., Jokat W., Jordan T., King E.C., Kohler J., Krabill W., Riger-Kusk, M., Langley K.A., Leitchenkov G., Leuschen C., Luyendyk B.P., Matsuoka, K., Mouginot J., Nitsche F.O., Nogi Y., Nost O.A., Popov S.V., Rignot E., Rippin D.M., Rivera A., Roberts J., Ross N., Siegert M.J., Smith A.M., Steinhage D., Studinger M., Sun B., Tinto B.K., Welch B.C., Wilson D., Young D.A., Xiangbin C. & Zirizzotti A. 2013. Bedmap2: improved ice bed, surface and thickness datasets for Antarctica. The Cryosphere 7, 375–393, https://doi.org/10.5194/tc-7-375-2013.
Gudmundsson G. 2003. Transmission of basal variability to a glacier surface. Journal of Geophysical Research—Solid Earth 108, article no. 2253, https://doi.org/10.1029/2002JB002107.
Helm V., Humbert A. & Miller H. 2014. Elevation and elevation change of Greenland and Antarctica derived from CryoSat-2. The Cryosphere 8, 1539–1559, https://doi.org/10.5194/tc-8-1539-2014.
Kamb B. & Echelmeyer K. 1986. Stress-gradient coupling in glacier flow: I. Longitudinal averaging of the influence of ice thickness and surface slope. Journal of Glaciology 32, 267–284, https://doi.org/10.3189/S0022143000015604.
Le Brocq A., Payne A. & Siegert M. 2006. West Antarctic balance calculations: impact of flux-routing algorithm, smoothing algorithm and topography. Computers and Geoscience 32, 1780–1795, https://doi.org/10.1016/j.cageo.2006.05.003.
McInnes B. & Budd W. 1984. A cross-sectional model for West Antarctica. Annals of Glaciology 5, 95–99, https://doi.org/10.1017/S0260305500003566
Mouginot J., Scheuchl B. & Rignot E. 2012. Mapping of ice motion in Antarctica using synthetic-aperture radar data. Remote Sensing 4, 2753-2767, https://doi.org/10.3390/rs4092753.
Nye J. 1952. The mechanics of glacier flow. Journal of Glaciology 2, 82–93, https://doi.org/10.1017/S0022143000033967
Nye J. 1957. The distribution of stress and velocity in glaciers and ice-sheets. Proceedings of the Royal Society of London 239, 113–133, https://doi.org/10.1098/rspa.1957.0026
Payne A. 1999. A thermomechanical model of ice flow in West Antarctica. Climate Dynamics 15, 115–125, https://doi.org/10.1126/science.1208336
Rignot E., Mouginot J. & Scheuchl B. 2011. Ice flow of the Antarctic ice sheet. Science 333, 1427–1430, https://doi.org/10.1126/science.1208336.
Rignot E., Mouginot J. & Scheuchl B. 2017 - present. MEaSUREs InSAR-based Antarctica ice velocity map, version 2.0. NASA Distributed Active Archive Center at the National Snow and Ice Data Center: Boulder, CO. https://doi.org/10.5067/D7GK8F5J8M8R Accessed on the internet at https://nsidc.org/data/nsidc-0484/versions/2 on 20 June 2017.
Roberts J.L., Warner R.C., Young D., Wright A., van Ommen T.D., Blankenship D.D., Siegert M., Young N.W., Tabacco I.E., Forieri A., Passerini A., Zirizzotti A. & Frezzotti M. 2011. Refined broad-scale sub-glacial morphology of Aurora Subglacial Basin, East Antarctica derived by an ice-dynamics-based interpolation scheme. Cryosphere 5, 551–560, https://doi.org/10.5194/tc-5-551-2011.
Young D.A, Roberts J.L., Ritz C., Frezzotti M., Quartini E., Cavitte M.G.P., Tozer C.R., Steinhage D., Urbini S., Corr H.F.J., van Ommen T. & Blankenship D.D. 2017. High resolution boundary conditions of an old ice target near Dome C, Antarctica. The Cryosphere 11, 1897–1911, https://doi.org/10.5194/tc-11-1897-2017.
Zwally H.J., Giovinetto M.B., Beckley M.A. & Saba J.L. 2012. Antarctic and Greenland drainage systems. Accessed on the internet at https://icesat4.gsfc.nasa.gov/cryo_data/ant_grn_drainage_systems.php on 23 February 2019.
Authors contributing to Polar Research retain copyright of their work, with first publication rights granted to the Norwegian Polar Institute. Read the journal's full Copyright- and Licensing Policy.