Earth’s Polar Ice Masses
New satellite observations and model physics to understand and improve forecasting of the Earth’s polar ice masses.
Research conducted by the current members of the Centre for Polar Observation and Modelling (CPOM) during provided the first space-borne estimates of the contribution of Antarctic ice sheet change to sea level rise and of inter-annual changes of Arctic sea thickness. This research demonstrated the potential advance that a dedicated space-borne polar altimeter could make in constraining the mass balance of the Earth’s polar ice masses and led to the competitive selection of CryoSat as the first ESA Earth explorer mission. The new technology used on CryoSat has now been incorporated into upcoming operational missions that will provide data to the world’s meteorological organisations. The research also led to CPOM generating new models of the physics of ice that are now being incorporated into global climate prediction models. In the same period CPOM has provide advice to government at a national and international level.
Understanding the changing mass fluxes of ice are central to improving predictions of future sea level rise, and to understand how the changing ice cover may affect the radiative balance of the atmosphere and buoyancy forcing of the ocean. In 1991 the European Space Agency (ESA) launched its first high latitude (to 81.5°) altimeter mission. This enabled the Climate Physics Group (CPG) at the Mullard Space Science Laboratory, whose work had previously focussed on technical aspects of retrieving precise measurements of ice elevation, to generate the first satellite derived estimates of Antarctic elevation change.
The results revealed that, although the ice sheet was in balance as a whole, a large area of marine terminated ice sheet in Western Antarctica was losing ice at a considerable rate. Further work at CPG, using the emerging technique of SAR interferometry, showed that the changes in ice elevation were associated with areas of high ice motion, highlighting the importance of ice dynamics in controlling ice sheet flow. In 1994 the CPG generated the first map of marine gravity over the Arctic Ocean leading to the discovery of a previously unmapped extinct spreading ridge in the Canada Basin. The research later led to the first satellite measurements of Arctic sea ice thickness revealing the key role that summer melt played in controlling the inter-annual fluctuations in Arctic sea ice mass. This research provided the impetus for significant investments aimed at advancing both the satellite technology used to make these measurements and the understanding of the physical processes governing the evolution of these ice masses.
The discovery that the largest changes in the ice sheets were occurring in the steep margins of Antarctica and that sea ice thickness could now be determined from space highlighted the shortcomings of current missions in their resolution (10km) and coverage (to 81.5°). In 1998 the CPG led a proposal for a new satellite, CryoSat, in response to an announcement of opportunity for a new series of Earth Explorer opportunity missions by ESA. CryoSat employed a new delay doppler radar altimeter, to improve the resolution of the measurements by a factor of 10, and extended the coverage to provide near complete (to 88°N) of the polar ice. The new radar developed for CryoSat has now been adopted for a new generation of operational altimeter satellites.
The recognition that physical processes controlling the evolution of the Earth’s polar ice masses, in particular the dynamics of ice sheet flow and the processing governing the melt and dynamics of sea ice, were poorly represented in numerical models used to predict future climate and sea level rise. To answer these needs the CPG submitted a proposal in 2000 for a new NERC Centre of Excellence, CPOM, to bring together the existing Earth observation expertise with an activity to address the deficiencies in the current models. CPOM developed new and innovative physical models governing the dynamic evolution of ice streams, sea ice mechanics and the evolution of melt-ponds on sea ice. These models are currently being incorporated into the worlds leading climate prediction models.
Related Links:
- D. J. Wingham, A. L. Ridout, R. Scharoo, R. J. Arthern, and C. K. Shum, "Antarctic Elevation Change from 1992 to 1996," Science, vol. 282, pp. 369-580, 1998 (cites 156).
- A. Shepherd, D. J. Wingham, J. A. D. Mansley, and H. F. J. Corr, "Inland thinning of Pine Island Glacier, West Antarctica," Science, vol. 291, pp. 862-864, FEB 2 2001 (cites 92).
- S. Laxon, N. Peacock, and D. Smith, "High interannual variability of sea ice thickness in the Arctic region," Nature, vol. 425, pp. 947-950, OCT 30 2003 (cites 171).
- D. J. Wingham, C. R. Francis, S. Baker, C. Bouzinac, D. Brockley, R. Cullen, P. de Chateau-Thierry, S. W. Laxon, U. Mallow, C. Mavrocordatos, L. Phalippou, G. Ratier, L. Rey, F. Rostan, P. Viau, and D. W. Wallis, "CryoSat: A mission to determine the fluctuations in Earth's land and marine ice fields," Natural Hazards and Oceanographic Processes from Satellite Data, vol. 37, pp. 841-871, 2006 (cites 36).
- £2,139,203 awarded for the Centre for Polar Observation and Modelling, NERC Centre of Excellence, NERC (PI: Wingham, UCL, UCL Co-I’s Laxon, Hunt, Feltham).
- J. Payne, A. Vieli, A. P. Shepherd, D. J. Wingham, and E. Rignot, "Recent dramatic thinning of largest West Antarctic ice stream triggered by oceans," Geophysical Research Letters, vol. 31, Dec 2004 (cites 113).
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