Hostname: page-component-586b7cd67f-rcrh6 Total loading time: 0 Render date: 2024-11-28T22:38:09.146Z Has data issue: false hasContentIssue false
  • English
  • Français

Drift of large tabular icebergs in response to atmospheric surface pressure gradients, an observational study

Published online by Cambridge University Press:  05 February 2010

Ian D. Turnbull
Ian D. Turnbull*
Affiliation:
University of Chicago, Department of the Geophysical Sciences, 123 York St., Apt. 7C, New Haven, CT 06511, USA
*
*[email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

While ocean current and winds certainly play a major role in guiding the trajectories of free-floating icebergs, the direct effect of atmospheric surface pressure gradients can also have an important influence on the trajectories of large icebergs whose horizontal dimensions are sufficiently great to span synoptic systems. This effect is examined as a way of understanding why icebergs B15A, B15J, B15K, and C16 became “trapped” in a limited region immediately north of Ross Island for a period of several years, without being grounded. This limited region is otherwise flushed annually by summer surface winds and currents; thus the delay of the northward drift of the large icebergs (particularly B15A and B15J) defied expectation. The best explanation for this unexpected iceberg behaviour is that the large volcanic massifs on Ross Island create a quasi-permanent surface pressure anomaly patterned as a dipole, with high pressure in the area upwind of the island (an area appropriately called Windless Bight), and low pressure in the downwind area of the iceberg parking lot. The surface pressure regime experienced by two icebergs B15A and B15K is estimated using Automatic Weather Station observations and Global Positioning System receivers deployed on their surfaces to explain why they remained trapped. Breakdown of the atmospheric pressure gradients allowed them to eventually escape from the region to the north-west.

Keywords

air/sea interactionAntarcticaB15barometric effectspolynyaRoss Sea
Type
Physical Sciences
Information
Antarctic Science , Volume 22 , Issue 2 , April 2010 , pp. 199 - 208
Copyright
Copyright © Antarctic Science Ltd 2010

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.)

References

Aoki, S. 2003. Seasonal and spatial variations of iceberg drift off Dronning Maud land, Antarctica, detected by satellite scatterometers. Journal of Oceanography, 59, 629–635.CrossRefGoogle Scholar
Bromwich, D.H., Monaghan, A.J., Powers, J.G., Cassano, J.J., Wei, H.-L., Kuo, Y.-H.Pellegrini, A. 2003. Antarctic mesoscale prediction system (amps): a case study from the 2000-01 field season. Monthly Weather Review, 131, 412–434.2.0.CO;2>CrossRefGoogle Scholar
Brunt, K.M., Sergienko, O.Macayeal, D.R. 2006. Observations of unusual fast-ice conditions in the southwest ross sea, antarctica: preliminary analysis of iceberg and storminess effects. Annals of Glaciology, 44, 183–187.CrossRefGoogle Scholar
Cathles, L.M., Okal, E.A.Macayeal, D.R. 2009. Seismic observations of sea swell on the floating Ross Ice Shelf, Antarctica. Journal of Geophysical Research, 114, 10.1029/2007JF000934.CrossRefGoogle Scholar
Johnson, E.S.Woert, M.L.V. 2006. Tidal currents of the Ross Sea and their time stability. Antarctic Science, 18, 141–154.CrossRefGoogle Scholar
Keys, H.J., Jacobs, S.Barnett, D. 1990. The calving and drift of iceberg b-9 in the floating Ross Sea, Antarctica. Antarctic Science, 2, 243–257.CrossRefGoogle Scholar
Lichey, C.Hellmer, H.H. 2001. Modeling giant-iceberg drift under the influence of sea ice in the Weddell Sea, Antarctica. Journal of Glaciology, 47, 452–460.CrossRefGoogle Scholar
Macayeal, D., Okal, M., Thom, J., Brunt, K., Kim, Y.-J.Bliss, A. 2008b. Tabular iceberg collisions with the coastal regime. Journal of Glaciology, 54, 371–386.CrossRefGoogle Scholar
Monaghan, A.J., Bromwich, D.H., Powers, J.G.Manning, K.W. 2005. The climate of the McMurdo, Antarctica, region as represented by one year of forecasts from the Antarctic mesoscale prediction system. Journal of Climate, 18, 1174–1189.CrossRefGoogle Scholar
Padman, L., King, M., Goring, D., Corr, H.Coleman, R. 2003. Ice-shelf elevation changes due to atmospheric pressure variations. Journal of Glaciology, 49, 521–526.CrossRefGoogle Scholar
Stearns, C.R.Weidner, G.A. 1993. Snow temperature, wind, speed, and wind direction around the Pegasus runway during 1992. Antarctic Journal of the United States, 28 (5), 291.Google Scholar
Stearns, C.R.Wendler, G. 1988. Research results from Antarctic automatic weather stations. Reviews of Geophysics, 26, 45–61.CrossRefGoogle Scholar
Taladier, J., Hyvernaud, O., Reymond, D.Okal, E. 2006. Hydroacoustic signals generated by parked and drifting icebergs in the southern Indian and Pacific oceans. Geophysical Journal International, 165, 817–834.CrossRefGoogle Scholar
Van Den Broeke, M.Lipzig, N.V. 2003. Factors controlling the near-surface wind field in Antarctica. Monthly Weather Review, 131, 733–743.2.0.CO;2>CrossRefGoogle Scholar
Wunsch, C.Stammer, D. 1997. Atmospheric loading and the oceanic “inverted barometer” effect. Reviews of Geophysics, 35, 79–107.CrossRefGoogle Scholar