Skip to main content
×
Home
    • Aa
    • Aa

Antarctic firn compaction rates from repeat-track airborne radar data: I. Methods

  • B. Medley (a1), S.R.M. Ligtenberg (a2), I. Joughin (a3), M.R. Van den Broeke (a2), S. Gogineni (a4) and S. Nowicki (a1)...
Abstract
Abstract

While measurements of ice-sheet surface elevation change are increasingly used to assess mass change, the processes that control the elevation fluctuations not related to ice-flow dynamics (e.g. firn compaction and accumulation) remain difficult to measure. Here we use radar data from the Thwaites Glacier (West Antarctica) catchment to measure the rate of thickness change between horizons of constant age over different time intervals: 2009–10, 2010–11 and 2009–11. The average compaction rate to ~25 m depth is 0.33 m a−1, with largest compaction rates near the surface. Our measurements indicate that the accumulation rate controls much of the spatio-temporal variations in the compaction rate while the role of temperature is unclear due to a lack of measurements. Based on a semi-empirical, steady-state densification model, we find that surveying older firn horizons minimizes the potential bias resulting from the variable depth of the constant age horizon. Our results suggest that the spatio-temporal variations in the firn compaction rate are an important consideration when converting surface elevation change to ice mass change. Compaction rates varied by up to 0.12 m a−1 over distances <6 km and were on average >20% larger during the 2010–11 interval than during 2009–10.

  • View HTML
    • Send article to Kindle

      To send this article to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle.

      Note you can select to send to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

      Find out more about the Kindle Personal Document Service.

      Antarctic firn compaction rates from repeat-track airborne radar data: I. Methods
      Available formats
      ×
      Send article to Dropbox

      To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your Dropbox account. Find out more about sending content to Dropbox.

      Antarctic firn compaction rates from repeat-track airborne radar data: I. Methods
      Available formats
      ×
      Send article to Google Drive

      To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your Google Drive account. Find out more about sending content to Google Drive.

      Antarctic firn compaction rates from repeat-track airborne radar data: I. Methods
      Available formats
      ×
Copyright
Corresponding author
Correspondence: B. Medley <brooke.c.medley@nasa.gov>
Linked references
Hide All

This list contains references from the content that can be linked to their source. For a full set of references and notes please see the PDF or HTML where available.

SA Arcone , VB Spikes , GS Hamilton and PA Mayewski (2004) Stratigraphic continuity in 400 MHz short-pulse radar profiles of firn in West Antarctica. Ann. Glaciol., 39, 195200 (doi: 10.3189/172756404781813925)

SA Arcone , VB Spikes and GS Hamilton (2005a) Stratigraphic variation within polar firn caused by differential accumulation and ice flow: interpretation of a 400 MHz short-pulse radar profile from West Antarctica. J. Glaciol., 51(174), 407422 (doi: 10.3189/172756505781829151)

SA Arcone , VB Spikes and GS Hamilton (2005b) Phase structure of radar stratigraphic horizons within Antarctic firn. Ann. Glaciol., 41(1), 1016 (doi: 10.3189/172756405781813267)

RJ Arthern , DG Vaughan , AM Rankin , R Mulvaney and ER Thomas (2010) In situ measurements of Antarctic snow compaction compared with predictions of models. J. Geophys. Res., 115(F3), F03011 (doi: 10.1029/2009JF001306)

H Bader (1954) Sorge’s Law of densification of snow on high polar glaciers. J. Glaciol., 2, 319323

BC Gunter and 7 others (2014) Empirical estimation of present-day Antarctic glacial isostatic adjustment and ice mass change. Cryosphere, 8(2), 743760 (doi: 10.5194/tc-8-743-2014)

RL Hawley and ED Waddington (2011) In situ measurements of firn compaction profiles using borehole optical stratigraphy. J. Glaciol., 57(202), 289294 (doi: 10.3189/002214311796405889)

RL Hawley , ED Waddington , GW Lamorey and KC Taylor (2004) Vertical-strain measurements in firn at Siple Dome, Antarctica. J. Glaciol., 50(170), 447452 (doi: 10.3189/172756504781829972)

MM Helsen and 7 others (2008) Elevation changes in Antarctica mainly determined by accumulation variability. Science, 320(5883), 16261629 (doi: 10.1126/science.1153894)

MM Herron and CC Langway Jr (1980) Firn densification: an empirical model. J. Glaciol., 25(93), 373385

I Joughin (2002) Ice-sheet velocity mapping: a combined interferometric and speckle-tracking approach. Ann. Glaciol., 34, 195201 (doi: 10.3189/172756402781817978)

NC Kruetzmann , W Rack , AJ McDonald and SE George (2011) Snow accumulation and compaction derived from GPR data near Ross Island, Antarctica. Cryosphere, 5(2), 391404 (doi: 10.5194/tc-5-391-2011)

JTM Lenaerts , MR Van den Broeke , WJ Van de Berg , EV Van Meijgaard and P Kuipers Munneke (2012) A new, high-resolution surface mass balance map of Antarctica (1979–2010) based on regional atmospheric climate modeling. Geophys. Res. Lett., 39(4), L04501 (doi: 10.1029/2011GL050713)

SRM Ligtenberg , MM Helsen and MR Van den Broeke (2011) An improved semi-empirical model for the densification of Antarctic firn. Cryosphere, 5(4), 809819 (doi: 10.5194/tc-5-809-2011)

SRM Ligtenberg , B Medley , MR Van den Broeke and P Kuipers Munneke (2015) Antarctic firn compaction rates from repeat-track airborne radar data: II. Firn model evaluation. Ann. Glaciol., 56(70) (doi: 10.3189/2015AoG70A204) (see paper in this issue)

H Looyenga (1965) Dielectric constants of heterogeneous mixtures. Physica, 31(3), 401406 (doi: 10.1016/0031-8914(65)90045-5)

B Medley and 12 others (2013) Airborne-radar and ice-core observations of annual snow accumulation over Thwaites Glacier, West Antarctica confirm the spatiotemporal variability of global and regional atmospheric models. Geophys. Res. Lett., 40(14), 36493654 (doi: 10.1002/grl.50706)

B Medley and 14 others (2014) Constraining the recent mass balance of Pine Island and Thwaites glaciers, West Antarctica with airborne observations of snow accumulation. Cryosphere, 8, 13751392 (doi: 10.5194/tc-8-1375-2014)

EM Morris and DJ Wingham (2011) The effect of fluctuations in surface density, accumulation and compaction on elevation change rates along the EGIG line, central Greenland. J. Glaciol., 57(203), 416430 (doi: 10.3189/002214311796905613)

EM Morris and DJ Wingham (2014) Densification of polar snow: measurements, modeling, and implications for altimetry. J. Geophys. Res.: Earth Surf., 119(2), 349365 (doi: 10.1002/2013JF002898)

JP Nicolas and DH Bromwich (2011) Climate of West Antarctica and influence of marine air intrusions. J. Climate, 24(1), 4967 (doi: 10.1175/2010JCLI3522.1)

B Panzer and 8 others (2013) An ultra-wideband, microwave radar for measuring snow thickness on sea ice and mapping near-surface internal layers in polar firn. J. Glaciol., 59(214), 244254 (doi: 10.3189/2013JoG12J128)

HD Pritchard , RJ Arthern , DG Vaughan and LA Edwards (2009) Extensive dynamic thinning on the margins of the Greenland and Antarctic ice sheets. Nature, 461(7266), 971975

HD Pritchard , SRM Ligtenberg , HA Fricker , DG Vaughan , Berg Van de and L Padman (2012) Antarctic ice-sheet loss driven by basal melting of ice shelves. Nature, 484(7395), 502505

F Rodriguez-Morales and 17 others (2013) Advanced multi-frequency radar instrumentation for polar research. IEEE Trans. Geosci. Remote Sens., 52(5), 28242842 (doi: 10.1109/TGRS. 2013.2266415)

T Scambos , T Haran , M Fahnestock , T Painter and J Bohlander (2007) MODIS-based Mosaic of Antarctica (MOA) data sets: continent-wide surface morphology and snow grain size. Remote Sens. Environ., 111(2), 242257 (doi: 10.1016/j.rse. 2006.12.020)

A Shepherd and 45 others (2012) A reconciled estimate of ice-sheet mass balance. Science, 338(6111), 11831189 (doi: 10.1126/science.1228102)

SB Simonsen , L Stenseng , G Aðalgeirsdóttir , RS Fausto , CS Hvidberg and P Lucas-Pichery (2013) Assessing a multilayered dynamic firn-compaction model for Greenland with ASIRAS radar measurements. J. Glaciol., 59(215), 545558 (doi: 10.3189/2013JoG12J158)

VB Spikes , GS Hamilton , SA Arcone , S Kaspari and PA Mayewski (2004) Variability in accumulation rates from GPR profiling on the West Antarctic plateau. Ann. Glaciol., 39, 238244 (doi: 10.3189/172756404781814393)

DJ Wingham , A Shepherd , A Muir and GJ Marshall , (2006) Mass balance of the Antarctic ice sheet. Philos. Trans. R. Soc. London, 364(1844), 16271635 (doi: 10.1098/rsta.2006.1792)

HJ Zwally and J Li , (2002) Seasonal and interannual variations of firn densification and ice-sheet surface elevation at the Greenland summit. J. Glaciol., 48(161), 199207 (doi: 10.3189/172756502781831403)

Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Annals of Glaciology
  • ISSN: 0260-3055
  • EISSN: 1727-5644
  • URL: /core/journals/annals-of-glaciology
Please enter your name
Please enter a valid email address
Who would you like to send this to? *
×

Keywords:

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 3 *
Loading metrics...

Abstract views

Total abstract views: 7 *
Loading metrics...

* Views captured on Cambridge Core between 26th July 2017 - 23rd September 2017. This data will be updated every 24 hours.