The Cryosphere Discussions www.the-cryosphere-discuss.net 1994-0432 1994-0440 3 3 2009 10.5194/tcd-3-805-2009 http://www.the-cryosphere-discuss.net/3/805/2009/ http://www.the-cryosphere-discuss.net/3/805/2009/tcd-3-805-2009.html http://www.the-cryosphere-discuss.net/3/805/2009/tcd-3-805-2009.pdf 805 829 2009-09-29 Interaction between ice sheet dynamics and subglacial lake circulation: a coupled modelling approach M. Thoma malte.thoma@awi.de K. Grosfeld C. Mayer F. Pattyn Bavarian Academy and Sciences, Commission for Glaciology, Alfons-Goppel-Str. 11, 80539 Munich, Germany Alfred Wegener Institute for Polar and Marine Research, Bussestrasse 24, 27570 Bremerhaven, Germany Laboratoire de Glaciologie, Département des Sciences de la Terre et de l'Environnement (DSTE), Université Libre de Bruxelles (ULB), CP 160/03, Avenue F.D. Roosevelt, 1050 Bruxelles, Belgium Subglacial lakes in Antarctica influence to a large extent the flow of the ice sheet. In this study we use an idealised lake geometry to study this impact. We employ a) an improved three-dimensional full Stokes ice flow model with a nonlinear rheology, b) a three-dimensional fluid dynamics model with eddy diffusion to simulate basal mass balance, and c) a newly developed coupler to exchange boundary conditions between individual models. Different boundary conditions are applied over grounded ice and floating ice. This results in significantly increased temperatures within the ice on top of the lake, compared to ice at the same depth outside the lake area. Basal melting of the ice sheet increases this lateral temperature gradient. Upstream the ice flow converges towards the lake and accelerates by about 10% whenever basal melting at the ice–lake boundary is present. Above and downstream of the lake, where the ice flow diverges, a velocity decrease of about 10% is simulated. Bell,~R E.: The role of subglacial water in ice-sheet mass balance, Nature Geosci., 1, 297–304, http://dx.doi.org/10.1038/ngeo186, doi:10.1038/ngeo186, 2008. Bell,~R E., Studinger,~M., Tikku,~A A., Clarke,~G K C., Gutner,~M M., and Meertens,~C.: Origin and fate of Lake Vostok water frozen to the base of the East Antarctic ice sheet, Nature, 416, 307–310, 2002. Carter,~S P., Blankenship,~D D., Peters,~M E., Young,~D A., Holt,~J W., and Morse,~D L.: Radar-based subglacial lake classification in Antarctica, Geochem. Geophys. Geosyst., 8, Q03016, \doi10.1029/2006GC001408, 2007. Comiso,~J C.: Variability and trends in Antarctic surface temperatures from in situ and satellite infrared measurements,~J. Climate, 13, 1674–1696, 2000. Duxbury,~N S., Zotikov,~I A., Nealson,~K H., Romanovsky,~V E., and Carsey,~F D.: A~numerical model for an alternative origin of Lake Vostok and its exobiological implications for Mars,~J. Geophys. Res., 106, 1453–1462, 2001. Filina,~I Y., Blankenship,~D D., Thoma,~M., Lukin,~V V., Masolov,~V N., and Sen,~M K.: New 3-D bathymetry and sediment distribution in Lake Vostok: Implication for pre-glacial origin and numerical modeling of the internal processes within the lake, Earth Planet. Sci. Lett., 276, 106­-114, doi:10.1016/j.epsl.2008.09.012, 2008. Fricker,~H A., Scambos,~T., Bindschadler,~R., and Padman,~L.: An active subglacial water system in west Antarctica mapped from space, Science, 315, 1544–1548, \doi10.1126/science.1136897, 2007. Gray,~L., Joughin,~I., Tulaczyk,~S., Spikes,~V B., Bindschadler,~R., and Jezek,~K.: Evidence for subglacial water transport in the West Antarctic Ice Sheet through three-dimensional satellite radar interferometry, Geophys. Res. Lett., 32, L03501, \doi10.1029/2004GL021387, 2005. Griffies,~S M.: Fundamentals of ocean climate models, Princeton University Press, Princeton, 2004. Grosfeld,~K., Gerdes,~R., and Determann,~J.: Thermohaline circulation and interaction beneath ice shelf cavities and the adjacent open ocean,~J. Geophys. Res., 102, 15595–15610, 1997. Holland,~D M. and Jenkins,~A.: Modeling Thermodynamic Ice-Ocean Interaction at the Base of an Ice Shelf,~J. Phys. Oceanogr., 29, 1787–1800, 1999. Hooke,~R L.: Flow law for polycrystalline ice in glaciers: Comparison of theoretical predictions, laboratory data, and field measurements, Rev. Geophys. Space Phys., 19, 664–672, 1981. Inman,~M.: Antarctic drilling: The plan to unlock Lake Vostok, Science, 310, 611–612, \doi10.1126/science.310.5748.611, 2005. Jouzel,~J., Petit,~J R., Souchez,~R., Barkov,~N I., Lipenkov,~V Y., Raynaud, ~D., Stievenard,~M., Vassiliev,~N I., Verbeke,~V., and Vimeux,~F.: More than 200 meters of lake ice above subglacial Lake Vostok, Antarctica, Science, 286, 2138–2141, \doi10.1126/science.286.5447.2138, 1999. Karl,~D M., Bird,~D F., Björkman,~K., Houlihan,~T., Shackelford,~R., and Tupas,~L.: Microorganisms in the accreted ice of Lake Vostok, Antarctica, Science, 286, 5447, \doi10.1126/science.286.5447.2144, 1999. Kwok,~R., Siegert,~M J., and Carsey,~F D.: Ice motion over Lake Vostok, Antarctica: constraints on inferences regarding the accreted ice,~J. Glaciol., 46, 689–694, 2000. Lavire,~C., Normand,~P., Alekhina,~I., Bulat,~S., Prieur,~D., Birrien,~J., Fournier,~P., Hänni,~C., and Petit,~J.: Presence of Hydrogenophilus thermoluteolus DNA in accretion ice in the subglacial Lake Vostok, Antarctica, assessed using rrs, cbb and hox, Environ. Microbiol., 8, 2106–2114, \doi10.1111/j.1462-2920.2006.01087.x, 2006. Lewis,~E L. and Perkin,~R G.: Ice pumps and their rates, J. Geophys. Res., 91, 11756–11762, 1986. Marshall,~S J.: Recent advances in understanding ice sheet dynamics, Earth Planet. Sci. Lett., 240, 191–204, 2005. Mayer,~C. and Siegert,~M J.: Numerical modelling of ice-sheet dynamics across the Vostok subglacial lake, central East Antarctica,~J. Glaciol., 46, 197–205, \doi10.3189/172756500781832981, 2000. Mayer,~C., Grosfeld,~K., and Siegert,~M.: Salinity impact on water flow and lake ice in Lake Vostok, Antarctica, Geophys. Res. Lett., 30, 1767, \doi10.1029/2003GL017380, 2003. Oswald,~G K A. and Robin,~G. d Q.: Lakes Beneath the Antarctic Ice Sheet, Nature, 245, 251–254, \doi10.1038/245251a0, 1973. Paterson,~W S B.: The Physics of Glaciers, Butterworth Heinemann, Oxford, 3 edn., 1994. Pattyn,~F.: A~new three-dimensional higher-order thermomechanical ice sheet model: Basic sensitivity, ice stream development, and ice flow across subglacial lakes,~J. Geophys. Res., 108, 1–15, \doi10.1029/2002JB002329, 2003. Pattyn,~F.: Comment on the comment by~M J. Siegert on "A~numerical model for an alternative origin of Lake Vostok and its exobiological implications for Mars" by~N S. Duxbury et al., J. Geophys. Res., 109, E11004, \doi10.1029/2004JE002329, 2004. Pattyn,~F.: Investigating the stability of subglacial lakes with a~full Stokes ice-sheet model, J. Glaciol., 54, 353–361, \doi10.3189/002214308784886171, http://www.ingentaconnect.com/content/igsoc/jog/2008/00000054/00000185/art00016, 2008. Pattyn,~F., de~Smedt,~B., and Souchez,~R.: Influence of subglacial Vostok lake on the regional ice dynamics of the Antarctic ice sheet: a~model study, J. Glaciol., 50, 583–589, 2004. Robin,~G D Q., Drewry,~D J., and Meldrum,~D T.: International studies of ice sheet and Bedrock, Philos. T Roy. Soc., 279, 185–196, 1977. Saito,~F., Abe-Ouchi,~A., and Blatter,~H.: Effects of first-order stress gradients in an ice sheet evaluated by a~three-dimensional thermomechanical coupled model, Ann. Glaciol., 37, 166–172, \doi10.3189/172756403781815645, 2003. Schiermeier,~Q.: Russia delays Lake Vostok drill, Antarctica's hidden water will keep its secrets for another year, Nature, 454, 258–259, \doi10.1038/454258a, 2008. Siegert,~M J.: Comment on "A~numerical model for an alternative origin of Lake Vostok and its exobiological implications for Mars" by Duxbury,~N S., Zotikov,~I A., Nealson,~K H., Romanovsky,~V E., and Carsey,~F D., J. Geophys. Res., 109, 1–3, \doi10.1029/2003JE002176, 2004. Siegert,~M J.: Reviewing the origin of subglacial Lake Vostok and its sensitivity to ice sheet changes, Prog. Phys. Geog., 29, 156–170, \doi10.1191/0309133305pp441ra, 2005. Siegert,~M J., Kwok,~R., Mayer,~C., and Hubbard,~B.: Water exchange between the subglacial Lake Vostok and the overlying ice sheet, Nature, 403, 643–646, \doi10.1038/35001049, 2000. Siegert, M J., Tranter, M., Ellis-Evans, J C., Priscu, J C., and Lyons, W B.: The hydrochemistry of Lake Vostok and the potential for life in Antarctic subglacial lakes, Hydrol. Process., 17, 795–814, 2003. Siegert,~M J., Hindmarsh,~R., Corr,~H., Smith,~A., Woodward,~J., King,~E C., Payne,~A J., and Joughin,~I.: Subglacial Lake Ellsworth: A~candidate for in situ exploration in West Antarctica, Geophys. Res. Lett., 31, 1–4, \doi10.1029/2004GL021477, 2004. Siegert,~M J., Carter,~S., Tabacco,~I E., Popov,~S., and Blankenship,~D D.: A~revised inventory of Antarctic subglacial lakes, Antarct. Sci., 17, 453–460, \doi10.1017/S0954102005002889, 2005. Siegert,~M J., Behar,~A., Bentley,~M., Blake,~D., Bowden,~S., Christoffersen, ~P., Cockell,~C., Corr,~H., Cullen,~D C., Edwards,~H., Ellery,~A., Ellis-Evans,~C., Griffiths,~G., Hindmarsh,~R., Hodgson,~D A., King,~E., Lamb,~H., Lane,~L., Makinson,~K., Mowlem,~M., Parnell,~J., Pearce,~D A., Priscu,~J., Rivera,~A., Sephton,~M A., Sims,~M R., Smith,~A M., Tranter, ~M., Wadham,~J L., Wilson,~G., and Woodward,~J.: Exploration of Ellsworth Subglacial Lake: a~concept paper on the development, organisation and execution of an experiment to explore, measure and sample the environment of a~West Antarctic subglacial lake, Rev. Env. Sci. Bio., 6, 161–179, \doi10.1007/s11157-006-9109-9, 2007. Smith,~B E., Fricher,~H A., Joughin,~I R., and Tulaczyk,~S.: An inventory of active subglacial lakes in Antarctica detected by ICESat (2003–2008), J. Glaciol., 55, 573–595, 2009. Studinger,~M., Bell,~R E., and Tikku,~A A.: Estimating the depth and shape of subglacial Lake Vostok's water cavity from aerogravity data, Geophys. Res. Lett., 31, L12401, \doi10.1029/2004GL019801, 2004. Thoma,~M., Grosfeld,~K., and Lange,~M A.: Impact of the Eastern Weddell Ice Shelves on water masses in the eastern Weddell Sea, J. Geophys. Res., 111, C12010, \doi10.1029/2005JC003212, 2006. Thoma,~M., Grosfeld,~K., and Mayer,~C.: Modelling mixing and circulation in subglacial Lake Vostok, Antarctica, Ocean Dynam., 57, 531–540, \doi10.1007/s10236-007-0110-9, 2007. Thoma,~M., Grosfeld,~K., and Mayer,~C.: Modelling accreted ice in subglacial Lake Vostok, Antarctica, Geophys. Res. Lett., 35, 1–6, \doi10.1029/2008GL033607, 2008a. Thoma,~M., Mayer,~C., and Grosfeld,~K.: Sensitivity of Lake Vostok's flow regime on environmental parameters, Earth Planet. Sci. Lett., 269, 242–247, \doi10.1016/j.epsl.2008.02.023, 2008b. Thoma,~M., Filina,~I., Grosfeld,~K., and Mayer,~C.: Modelling circulation and basal mass balance of subglacial Lake Concordia, Antarctica, Earth Planet. Sci. Lett., 286, 278­â€“284, \doi10.1016/j.epsl.2009.06.037, 2009. Tikku,~A A., Bell,~R E., Studinger,~M., and Clarke,~G K C.: Ice flow field over Lake Vostok, East Antarctica inferred by structure tracking, Earth Planet. Sci. Lett., 227, 249–261, \doi10.1016/j.epsl.2004.09.021, 2004. Tikku,~A A., Bell,~R E., Studinger,~M., Clarke,~G K C., Tabacco,~I., and Ferraccioli,~F.: Influx of meltwater to subglacial Lake Concordia, east Antarctica, J. Glaciol., 51, 96–104, 2005. Walsh,~D.: A~note on eastern-boundary intensification of flow in Lake Vostok, Ocean Modell., 4, 207–218, 2002. Weertman,~J.: Creep of ice, in: Physics and Chemistry of Ice, edited by: Whalley,~E., Jones,~S J., and Gold,~L W., Royal Society of Canada, Ottawa, 320–337, 1973. Wells,~M G. and Wettlaufer,~J S.: Circulation in Lake Vostok: A~laboratory analogue study, Geophys. Res. Lett., 35, 1–5, \doi10.1029/2007GL032162, 2008. Williams,~M J M.: Application of a~three-dimensional numerical model to Lake Vostok: An Antarctic subglacial lake, Geophys. Res. Lett., 28, 531–534, 2001. Williams,~M J M., Grosfeld,~K., Warner,~R C., Gerdes,~R., and Determann,~J.: Ocean circulation and ice-ocean interaction beneath the Amery Ice Shelf, Antarctica, J. Geophys. Res., 106, 22383–22400, 2001. Wingham,~D J., Siegert,~M J., Shepherd,~A., and Muir,~A S.: Rapid discharge connects Antarctic subglacial lakes, Nature, 440, 1033–1036, \doi10.1038nature04660, 2006. Woodward,~J., Siegert,~M J., Hindmarsh,~R., Corr,~H., Smith,~A., King,~E C., Payne,~A J., Joughin,~I., and Thoma,~M.: Bathymetry and basal mass balance of Subglacial Lake Ellsworth, West Antarctica, in preparation, 2009. Wüest,~A. and Carmack,~E.: A~priori estimates of mixing and circulation in the hard-to-reach water body of Lake Vostok, Ocean Modell., 2, 29–43, 2000.