Skip to main content Accessibility help
Hostname: page-component-6c8bd87754-clkrv Total loading time: 0.243 Render date: 2022-01-20T18:49:38.619Z Has data issue: true Feature Flags: { "shouldUseShareProductTool": true, "shouldUseHypothesis": true, "isUnsiloEnabled": true, "metricsAbstractViews": false, "figures": true, "newCiteModal": false, "newCitedByModal": true, "newEcommerce": true, "newUsageEvents": true }

The dynamics of a subglacial salt wedge

Published online by Cambridge University Press:  20 May 2020

Earle A. Wilson*
Environmental Science and Engineering, California Institute of Technology, Pasadena,CA 91125, USA
Andrew J. Wells
Atmospheric, Oceanic and Planetary Physics, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
Ian J. Hewitt
Mathematical Institute, University of Oxford, Oxford OX1 2JD, UK
Claudia Cenedese
Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
Email address for correspondence:


Marine-terminating glaciers, such as those along the coastline of Greenland, often release meltwater into the ocean in the form of subglacial discharge plumes. Though these plumes can dramatically alter the mass loss along the front of a glacier, the conditions surrounding their genesis remain poorly constrained. In particular, little is known about the geometry of subglacial outlets and the extent to which seawater may intrude into them. Here, the latter is addressed by exploring the dynamics of an arrested salt wedge – a steady-state, two-layer flow system where salty water partially intrudes a channel carrying fresh water. Building on existing theory, we formulate a model that predicts the length of a non-entraining salt wedge as a function of the Froude number, the slope of the channel and coefficients for interfacial and wall drag. In conjunction, a series of laboratory experiments were conducted to observe a salt wedge within a rectangular channel. For experiments conducted with laminar flow (Reynolds number $Re<800$), good agreement with theoretical predictions are obtained when the drag coefficients are modelled as being inversely proportional to $Re$. However, for fully turbulent flows on geophysical scales, these drag coefficients are expected to asymptote toward finite values. Adopting reasonable drag coefficient estimates for this flow regime, our theoretical model suggests that typical subglacial channels may permit seawater intrusions of the order of several kilometres. While crude, these results indicate that the ocean has a strong tendency to penetrate subglacial channels and potentially undercut the face of marine-terminating glaciers.

JFM Papers
© The Author(s), 2020. Published by Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)


Adams, E. E., Sahoo, D., Liro, C. R. & Zhang, X. 1994 Hydraulics of seawater purging in tunneled wastewater outfall. J. Hydraul. Engng ASCE 120 (2), 209226.CrossRefGoogle Scholar
Ali, K. H. M., Wose, A. E. & Burrows, R. 1995 Characteristics of primary salt wedges in long sea outfalls. Trans. Ecol. Environ. 7, 295304.Google Scholar
Arita, M. & Jirka, G. H. 1987a TwoLayer model of saline wedge. I: entrainment and interfacial friction. J. Hydraul. Engng ASCE 113 (10), 12291246.CrossRefGoogle Scholar
Arita, M. & Jirka, G. H. 1987b TwoLayer model of saline wedge. II: prediction of mean properties. J. Hydraul. Engng ASCE 113 (10), 12491263.CrossRefGoogle Scholar
van den Broeke, M., Bamber, J., Ettema, J., Rignot, E., Schrama, E., van de Berg, W. J., van Meijgaard, E., Velicogna, I. & Wouters, B. 2009 Partitioning recent greenland mass loss. Science 326 (5955), 984986.CrossRefGoogle ScholarPubMed
Carroll, D., Sutherland, D. A., Hudson, B., Moon, T., Catania, G. A., Shroyer, E. L., Nash, J. D., Bartholomaus, T. C., Felikson, D., Stearns, L. A. et al. 2016 The impact of glacier geometry on meltwater plume structure and submarine melt in Greenland fjords. Geophys. Res. Lett. 43 (18), 97399748.CrossRefGoogle Scholar
Cenedese, C. & Gatto, V. M. 2016 Impact of a localized source of subglacial discharge on the heat flux and submarine melting of a tidewater glacier: a laboratory study. J. Phys. Oceanogr. 46 (10), 31553163.CrossRefGoogle Scholar
Chen, N. H. 1979 An explicit equation for friction factor in pipe. Ind. Engng Chem. Fundam. 18 (3), 296297.CrossRefGoogle Scholar
Dermissis, V. 1993 Seawater intrusion in submarine karst channel of rectangular cross-section. WIT Trans. Ecol. Environ. 2, 18.Google Scholar
Ezhova, E., Cenedese, C. & Brandt, L. 2018 Dynamics of three-dimensional turbulent wall plumes and implications for estimates of submarine glacier melting. J. Phys. Oceanogr. 48 (9), 19411950.CrossRefGoogle Scholar
Fried, M. J., Catania, G. A., Bartholomaus, T. C., Duncan, D., Davis, M., Stearns, L. A., Nash, J., Shroyer, E. & Sutherland, D. 2015 Distributed subglacial discharge drives significant submarine melt at a Greenland tidewater glacier. Geophys. Res. Lett. 42, 93289366.CrossRefGoogle Scholar
Geyer, W. R. & Farmer, D. M. 1989 Tide-induced variation of the dynamics of a salt wedge estuary. J. Phys. Oceanogr. 19 (8), 10601072.2.0.CO;2>CrossRefGoogle Scholar
Geyer, W. R. & Ralston, D. K. 2011 The Dynamics of Strongly Stratified Estuaries, chap. 2, pp. 3751. Elsevier.Google Scholar
Hansen, D. V. & Rattray, M. 1966 New dimensions in estuary classification. Limnol. Oceanogr. 11 (3), 319326.CrossRefGoogle Scholar
Jackson, R. H., Shroyer, E. L., Nash, J. D., Sutherland, D. A., Carroll, D., Fried, M. J., Catania, G. A., Bartholomaus, T. C. & Stearns, L. A. 2017 Near-glacier surveying of a subglacial discharge plume: Implications for plume parameterizations. Geophys. Res. Lett. 44 (13), 68866894.CrossRefGoogle Scholar
Jackson, R. H., Straneo, F. & Sutherland, D. A. 2014 Externally forced fluctuations in ocean temperature at Greenland glaciers in non-summer months. Nat. Geosci. 7 (7), 503508.CrossRefGoogle Scholar
Jenkins, A. 2011 Convection-driven melting near the grounding lines of ice shelves and tidewater glaciers. J. Phys. Oceanogr. 41 (12), 22792294.CrossRefGoogle Scholar
Kimura, S., Holland, P. R., Jenkins, A. & Piggott, M. 2014 The effect of meltwater plumes on the melting of a vertical glacier face. J. Phys. Oceanogr. 44 (12), 30993117.CrossRefGoogle Scholar
Lu, P., Li, Z., Cheng, B. & Leppäranta, M. 2011 A parameterization of the ice-ocean drag coefficient. J. Geophys. Res. 116 (C7), C07019.CrossRefGoogle Scholar
McConnochie, C. D. & Kerr, R. C. 2017 Enhanced ablation of a vertical ice wall due to an external freshwater plume. J. Fluid Mech. 810, 429447.CrossRefGoogle Scholar
Meier, M. F., Dyurgerov, M. B., Rick, U. K., O’Neel, S., Pfeffer, W. T., Anderson, R. S., Anderson, S. P. & Glazovsky, A. F. 2007 Glaciers dominate eustatic sea-level rise in the 21st century. Science 317 (5841), 10641067.CrossRefGoogle ScholarPubMed
Moody, L. F. 1944 Friction factors for pipe flow. Trans. ASME 66, 671684.Google Scholar
O’Leary, M. & Christoffersen, P. 2013 Calving on tidewater glaciers amplified by submarine frontal melting. Cryosphere 7 (1), 119128.CrossRefGoogle Scholar
Pritchard, H. D., Ligtenberg, S. R. M., Fricker, H. A., Vaughan, D. G., Van Den Broeke, M. R. & Padman, L. 2012 Antarctic ice-sheet loss driven by basal melting of ice shelves. Nature 484 (7395), 502505.CrossRefGoogle ScholarPubMed
Rignot, E., Fenty, I., Xu, Y., Cai, C., Velicogna, I., Cofaigh, C. Ó., Dowdeswell, J. A., Weinrebe, W., Catania, G. & Duncan, D. 2016 Bathymetry data reveal glaciers vulnerable to iceocean interaction in Uummannaq and Vaigat glacial fjords, west Greenland. Geophys. Res. Lett. 43 (6), 26672674.CrossRefGoogle Scholar
Rignot, E., Koppes, M. & Velicogna, I. 2010 Rapid submarine melting of the calving faces of West Greenland glaciers. Nat. Geosci. 3 (3), 187191.CrossRefGoogle Scholar
Rignot, E., Velicogna, I., van den Broeke, M. R., Monaghan, A. & Lenaerts, J. T. M. 2011 Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise. Geophys. Res. Lett. 38 (5), L05503.CrossRefGoogle Scholar
Röthlisberger, H. 1972 Water pressure in intra- and subglacial channels. J. Glaciol. 11 (62), 177203.CrossRefGoogle Scholar
Sargent, F. E. & Jirka, G. H. 1987 Experiments on saline wedge. J. Hydraul. Engng ASCE 113 (10), 13071323.CrossRefGoogle Scholar
Schijf, J. B. & Schonfeld, J. C. 1953 Theoretical Considerations on the Motion of Salt and Fresh Water, Proc. Minnesota International Hydraulics Convention, (Univ. of Minnesota), pp. 321333.Google Scholar
Slater, D. A., Goldberg, D. N., Nienow, P. W. & Cowton, T. R. 2016 Scalings for submarine melting at tidewater glaciers from buoyant plume theory. J. Phys. Oceanogr. 46 (6), 18391855.CrossRefGoogle Scholar
Slater, D. A., Nienow, P. W., Cowton, T. R., Goldberg, D. N. & Sole, A. J. 2015 Effect of near-terminus subglacial hydrology on tidewater glacier submarine melt rates. Geophys. Res. Lett. 42 (8), 28612868.CrossRefGoogle Scholar
Straneo, F. & Cenedese, C. 2015 The dynamics of Greenland’s glacial fjords and their role in climate. Annu. Rev. Mar. Sci. 7 (1), 89112.CrossRefGoogle ScholarPubMed
Straneo, F., Curry, R. G., Sutherland, D. A., Hamilton, G. S., Cenedese, C., Våge, K. & Stearns, L. A. 2011 Impact of fjord dynamics and glacial runoff on the circulation near Helheim Glacier. Nat. Geosci. 4 (5), 322327.CrossRefGoogle Scholar
Werder, M. A., Hewitt, I. J., Schoof, C. G. & Flowers, G. E. 2013 Modeling channelized and distributed subglacial drainage in two dimensions. J. Geophys. Res. Earth Surf. 118 (4), 21402158.CrossRefGoogle Scholar
Xu, Y., Rignot, E., Menemenlis, D. & Koppes, M. 2012 Numerical experiments on subaqueous melting of Greenland tidewater glaciers in response to ocean warming and enhanced subglacial discharge. Ann. Glaciol. 53 (60), 229234.CrossRefGoogle Scholar

Send article to Kindle

To send this article to your Kindle, first ensure 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. Find out more about sending to your Kindle.

Note you can select to send to either the or variations. ‘’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘’ 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.

The dynamics of a subglacial salt wedge
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 <service> account. Find out more about sending content to Dropbox.

The dynamics of a subglacial salt wedge
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 <service> account. Find out more about sending content to Google Drive.

The dynamics of a subglacial salt wedge
Available formats

Reply to: Submit a response

Please enter your response.

Your details

Please enter a valid email address.

Conflicting interests

Do you have any conflicting interests? *