Posts Tagged «Ian Joughin»

An article written by T. Moon, I. Joughin, B. Smith and I. Howat from Science/AAAS journal.

Alley, R. B., P. U. Clark, P. Huybrechts, and I. Joughin,’ Ice-sheet and sea-level changes’, Science, 310, 456-460, 2005.

Alley, R. B., M. Fahnestock, and I. Joughin, Climate change understanding glacier flow in changing times, Science, 322(5904), 1061-1062, 2008.

Alley, R. B., H. J. Horgan, I. Joughin, K. M. Cuffey, T. K. Dupont, B. R. Parizek, S. Anandakrishnan, and J. Bassis, A Simple Law for Ice-Shelf Calving, Science, 322(5906), 1344-1344,2008.

This investigation’s major goal is to develop and use models constrained by satellite and ground observations to study the controls on fast ice stream flow.

NASA climate scientists report that Antarctica has gained ice in the form of snow accumulation. This study was recently published in the Journal of Glaciology and reporters have sought comments from their peers at the Polar Science Center.

Deeply embayed ice shelves and narrower fringing ice shelves surround much of Antarctica. Recent results indicate that these ice shelves help regulate the flow of upstream glaciers and ice streams (“ice-shelf buttressing”). This investigation focuses on determining the mass balance of Antarctica’s non-Peninsula ice shelves and on improving our knowledge of the processes that control basal melt.

Results of a recent long-term and large-scale simulation of the collapse of the Western Antarctic Ice Sheet (WAIS) show that the destabilization of the entire ice sheet would be irreversible if current conditions don’t change by 2075.

Science Daily reports on a study recently published in Geophysical Research Letters where satellite measurements assessed glacier flow in the Antarctic Peninsula. PSC’s Ian Joughin was part of an international team of researchers, led by the UK Centre for Polar Observation and Modelling at the University of Leeds, and is one of the co-authors.

Bamber, J.L., R.J. Hardy, P. Huybrechts, and I. Joughin, A comparison of balance velocities, measured velocities and thermomechanically modelled velocities for the Greenland Ice Sheet, Ann. Glaciol., 30, 211-216, 2000.

Bamber, J.L., R.J. Hardy, and I. Joughin, An analysis of balance velocities over the Greenland ice sheet and comparison with synthetic aperture radar interferometry, J. Glaciol., 46(152), 67-74, 2000.

Bamber, J.L., D.G. Vaughan, and I. Joughin, Widespread complex plow in the interior of the Antarctic Ice Sheet, Science, 287(5456), 1248-1250, 2000.

Bamber, J. L., F. Ferraccioli, I. Joughin, T. Shepherd, D. M. Rippin, M. J. Siegert, and D. G. Vaughan,’ East Antarctic ice stream tributary underlain by major sedimentary basin’, Geology, 34, 33-36, 2006

Bell, R. E., M. Studinger, C. A. Shuman, M. A. Fahnestock, and I. Joughin,’ Large subglacial lakes in East Antarctica at the onset of fast-flowing ice streams’, Nature, 445, 904-907, 2007.

Bougamont, M., S. Tulaczyk, and I. Joughin, Numerical investigations of the slow-down of Whillans Ice Stream, West Antarctica: is it shutting down like Ice Stream C?, in Annals of Glaciology, Vol 37, pp. 239-246, 2003.

Bougamont, M., S. Tulaczyk, and I. Joughin, Response of subglacial sediments to basal freeze- on – 2. Application in numerical modeling of the recent stoppage of Ice Stream C, West Antarctica, J. Geophys. Res.-Solid Earth, 108(B4), art. no.-2223, 2003.

Christianson, K., Bushuk, M., Dutrieux, P., Parizek, B.R., Joughin, I.R., Alley, R.B., Shean, D.E., Abrahamsen, E.P., Anandakrishnan, S., Heywood, K.J., Kim, T., Lee, S.H., Nicholls, K., Stanton, T., Truffer, M., Webber, B.G.M., Jenkings, A., Jacobs, S., Bindschadler, R., Holland, D.M., Sensitivity of Pine Island Glacier to observed ocean forcing: PIG response to ocean forcing, Geophys. Res. Lett., 43(20), 10,817-10,825, doi:10.1002/2016GL070500, 2016.

Christoffersen, P., R. I. Mugford, K. J. Heywood, I. Joughin, J. A. Dowdeswell, J. P. M. Syvitski, A. Luckman, and T. J. Benham, Warming of waters in an East Greenland fjord prior to glacier retreat: mechanisms and connection to large-scale atmospheric conditions, Cryosphere, 5(3), 701-714, 2011.

Colgan, W., H. Rajaram, R. Anderson, K. Steffen, T. Phillips, I. Joughin, H. J. Zwally, and W. Abdalati, The annual glaciohydrology cycle in the ablation zone of the Greenland ice sheet: Part 1. Hydrology model, Journal Of Glaciology, 57(204), 697-709, 2011.

Das, S. B., I. Joughin, M. Behn, M. King, I. M. Howat, D. Lizarralde, and M. Bahtia, Water- driven fracture propagation to the bed of the Greenland Ice Sheet during supraglacial lake drainage, Science, 320(5877), 778-781, 2008.

We are using field and remote sensing data to investigate Elevation Change Anomalies (ECAs) discovered recently in the Ross Sea sector of the West Antarctic Ice Sheet (WAIS), which reveal the filling and draining of subglacial lakes.

Fahnestock, M., W. Abdalati, I. Joughin, J. Brozena, and P. Gogineni, High geothermal heat row, basal melt, and the origin of rapid ice how in central Greenland, Science, 294(5550), 2338-2342, 2001.

Fahnestock, M.A., I. Joughin, T.A. Scambos, R. Kwok, W.B. Krabill, and S. Gogineni, Ice- stream-related patterns of ice flow in the interior of northeast Greenland, J. Geophys. Res.- Atmos., 106(D24), 34035-34045, 2001.

Fricker, H. A., T. Scambos, S. Carter, C. Davis, T. Haran, and I. Joughin, Synthesizing multiple remote-sensing techniques for subglacial hydrologic mapping: application to a lake system beneath MacAyeal Ice Stream, West Antarctica, J. Glaciol., 56(196), 187-199, 2010.

Gray, L., N. Short, R. Bindschadler, I. Joughin, L. Padman, P. Vornberger, and A. Khananian, RADARSAT interferometry for Antarctic grounding-zone mapping, Ann. of Glaciol., 34, 269-276, 2002.

Gray, L., I. Joughin, S. Tulaczyk, V.B. Spikes, R. Bindschadler, and K.C. Jezek,’ Evidence for subglacial water transport in the West Antarctic ice sheet through three-dimensional satellite radar interferometry’, Geophys. Res. Lett., 32, 10.1029/2004GL021387, 2005.

Numerous recent studies have revealed rapid change in ice discharge from Greenland’s outlet glaciers. A near doubling in flow speed of many of Greenland’s glaciers substantially increased the rate at which the ice sheet calved icebergs to the ocean over the last five years.

The Washington Post asks Ian Joughin about a recent study, in the journal Science Advances, using a GPS network which measures ice sheet mass loss in Greenland and re-evaluates previous studies.

UW Today reports on the results of a study recently published in The Cryosphere, involving PSC’s Ben Smith, Alex Huth, and Ian Joughin who teamed up with the University of Edinburgh and, using satellite data, identified a considerable drainage of interconnected lakes below West Antarctica’s Thwaites Glacier.

Hogg, A.E., A. Shepherd, S.L. Cornford, K.H. Briggs, N. Gourmelen, J. Graham, I. Joughin, J. Mouginot, T. Nagler, A.J. Payne, E. Rignot, J. Wuite. (2017), Increased ice flow in Western Palmer Land linked to ocean melting, Geophys. Res. Lett., 44, doi: 10.1002/2016GL072110

Howat, I. M., I. Joughin, S. Tulaczyk, and S. Gogineni,’ Rapid retreat and acceleration of Helheim Glacier, east Greenland’, Geophys. Res. Lett., 32, 2005.

Howat, I. M., I. Joughin, and T. A. Scambos,’ Rapid changes in ice discharge from Greenland outlet glaciers’, Science, 315, 1559-1561, 2007.

Howat, I. M., I. Joughin, M. Fahnestock, B. E. Smith, and T. A. Scambos, Synchronous retreat and acceleration of southeast Greenland outlet glaciers 2000-06: ice dynamics and coupling to climate, J. Glaciol., 54(187), 646-660, 2008.

Howat, I. M., Y. Ahn, I. Joughin, M. R. van den Broeke, J. T. M. Lenaerts, and B. Smith, Mass balance of Greenland’s three largest outlet glaciers, 2000-2010, Geophys. Res. Lett., 38, 2011.

Hulbe, C.L., I.R. Joughin, D.L. Morse, and R.A. Bindschadler, Tributaries to West Antarctic ice streams: Characteristics deduced from numerical modelling of ice flow, Ann. Glaciol., 31, 184-190, 2000.

Hulbe, C.L., W.L. Wang, I.R. Joughin, and M.J. Siegert, The role of lateral and vertical shear in tributary flow toward a West Antarctic ice stream, in Annals of Glaciology, Vol 36, pp. 244- 250, 2003.

Hulbe, C. L., Johnston, R., Joughin, I. & Scambos, T.,’ Marine ice modification of fringing ice shelf flow’, Arctic Antarctic And Alpine Research, 37, 323-330, 2005.

IceBridge is a NASA project that supports the acquisition of various data from aircraft in both polar regions that will bridge the gap in coverage between the now defunct ICESat satellite and the next generation ICESat II to be launched in 2015 at the earliest. The main focuses of the data acquisition will be laser altimetry and radar measurements of ice sheets (Greenland and Antarctica) and sea ice (Arctic and Antarctica).

June 18, 2019 – This week is ICESat-2 Hackweek 2019, held at the University of Washington. Participants are learning about technologies used to access and process ICESat-2 data with a focus on the cryosphere.

IMBIE [includes B. Smith & I. Joughin]. 2018. Mass balance of the Antarctic Ice Sheet from 1992 to 2017. Nature. 558:219–222.

PI: Ian Joughin The West Antarctic Ice Sheet is losing mass, in large part because of rapid thinning of the Amundsen Coast glaciers. Estimates of Amundsen Coast thinning range from 46 to 86 Gtons/yr, with the 40-Gton/yr difference in estimates being nearly equivalent to the combined outflow of Mercer, Whillans, Kamb, and Bindschadler ice streams (46 Gtons/yr). While warmer ocean temperatures may drive this thinning, the large uncertainties in the current mass balance estimates largely arise from poor knowledge of the snowfall accumulation over Pine Island, Thwaites, Smith, Pope and Kohler glaciers. This International Polar Year project is determining accumulation rates in this vastly under-sampled region to remove the large uncertainties in current mass balance estimates.

Interferometric synthetic aperture radar (InSAR) is a widely used tool for measuring ice sheet velocity in the Polar Regions. However, the ionosphere is a prevalent source of noise in these data. Ian Joughin is a co-author of a study, published in the May 2018 issue of Remote Sensing Environment, where a split-spectrum technique was utilized, and its performance analyzed, for correcting ionospheric effects in InSAR-based ice velocity measurements in Greenland and Antarctica. Read on to learn if the technique effectively reduced noise level…

Airborne and satellite observations of West Antarctic topography and glacier flow speeds are combined with a computer model simulating ocean-driven glacier melting to show that the ice sheet’s collapse is already underway.

Joughin, I., D.R. MacAyeal, and S. Tulaczyk,’ Basal shear stress of the Ross ice streams from control method inversions’, J. Geophys. Res., 109, B09405, 10.1029/2003JB002960, 2004.

Joughin, I. & Bamber, J. L.,’ Thickening of the ice stream catchments feeding the Filchner-Ronne Ice Shelf, Antarctica’, Geophysical Research Letters, 32, 2005.

Joughin, I., S. Tulaczyk, D.R. MacAyeal, and H. Engelhardt,’ Melting and freezing beneath the Ross ice streams, Antarctica’, J. Glaciol., 50, 96-108, 2004.

Joughin, I. & MacAyeal, D. R,’ Calving of large tabular icebergs from ice shelf rift systems’, Geophysical Research Letters, 32, 2005.

Joughin, I., et al.,’ Continued deceleration of Whillans Ice Stream, West Antarctica’, Geophys. Res. Lett., 32, 2005.

Joughin, I., D. E. Shean, B. E. Smith, and P. Dutrieux, Grounding line variability and subglacial lake drainage on Pine Island Glacier, Antarctica, Geophys. Res. Lett., 43(17), 9093–9102, doi:10.1002/2016GL070259, 2016

Joughin, I., S. Tulaczyk, M. Fahnestock, and R. Kwok, A mini-surge on the Ryder Glacier, Greenland, observed by satellite radar interferometry, Science, 274(5285), 228-230, 1996.