Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2018 Feb;64(243):1-11.
doi: 10.1017/jog.2017.73. Epub 2017 Nov 21.

A Complete Map of Greenland Ice Velocity Derived from Satellite Data Collected over 20 Years

Ian Joughin  1 , Ben E Smith  1 , Ian M Howat  2
Affiliations

A Complete Map of Greenland Ice Velocity Derived from Satellite Data Collected over 20 Years

Ian Joughin et al. J Glaciol. 2018 Feb.

Abstract

While numerous maps of Greenland ice flow velocity exist, most have gaps in coverage and/or accuracy is limited. We processed a large volume of synthetic aperture radar (SAR) and Landsat 8 imagery collected between 1995 and 2015 to produce a nearly complete map of ice flow velocity for Greenland at a far greater accuracy than most prior products. We evaluated the accuracy of this map by comparing it with a variety of measured and estimated velocities. For the slow-moving interior of the ice sheet, where estimates are determined from interferometric phase, the errors are ~2 m a-1 or better. For coastal areas, where estimates are determined entirely from speckle- or feature-tracking methods, errors are 2-3 m a-1, which is in good agreement with the estimated formal errors. Especially for the slow-moving majority of the ice sheet, this map provides an important source of data for numerous types of glaciological studies.

PubMed Disclaimer

Figures

Figure 1.
Figure 1.
Locations of the GPS, balance (Vb) and rock (Vr) control points used to calibrate the offsets and interferograms included in the velocity mosaics plotted over the complete velocity mosaic (color background). Points are color-coded by type as shown in the legend and described in the text.
Figure 2.
Figure 2.
Ice sheet velocity estimates plot from a) speckle tracking b) interferometric phase in interior regions where phase can be unwrapped, and c) Landsat 8. Speeds are displayed as color over a gray-scale SAR mosaic (Joughin, Smith, Howat, Moon, and others, 2016).
Figure 3.
Figure 3.
Final velocity mosaic formed as an inverse-error-weighted average of the results shown in Figure 2. This map is freely distributed through the National Snow and Ice Data Center (http://dx.doi.org/10.5067/QUA5Q9SVMSJG).
See this image and copyright information in PMC

References

    1. Ahlstrøm AP, Andersen SB, Andersen ML, Machguth H, Nick FM, Joughin I, Reijmer CH, van de Wal RSW, Merryman Boncori JP, Box JE, Citterio M, van As D, Fausto RS and Hubbard A (2013) Seasonal velocities of eight major marine-terminating outlet glaciers of the Greenland ice sheet from continuous in situ GPS instruments. Earth Syst. Sci. Data 5(2), 277–287 (doi:10.5194/essd-5-277-2013) - DOI
    1. Ahn Y and Howat IM (2011) Efficient Automated Glacier Surface Velocity Measurement From Repeat Images Using Multi-Image/Multichip and Null Exclusion Feature Tracking. IEEE T Geosci Remote 49(8), 2838–2846 (doi:10.1109/TGRS.2011.2114891) - DOI
    1. Bamber JL, Hardy RJ and Joughin I (2002) An analysis of balance velocities over the Greenland ice sheet and comparison with synthetic aperture radar intcrferometry (vol 46, pg 67, 2000). J Glaciol 48(162), 481–481
    1. Cuffey KM and Paterson W (2010) The Physics of Glaciers. 4 edn. Amsterdam
    1. Ettema J, Van Den Broeke MR, van Meijgaard E, van de Berg WJ, Bamber JL, Box JE and Bales RC (2009) Higher surface mass balance of the Greenland ice sheet revealed by high-resolution climate modeling. Geophys Res Lett 36(12), L12501 (doi:10.1029/2009GL038110) - DOI

LinkOut - more resources