Sea Ice References

Observed Changes in Arctic Sea Ice Properties: An Annotated Bibliography A Contribution to the NSF FWI Changes and Attribution Working Group Marika Holland

This bibliography briefly summarizes selected papers addressing observed changes in arctic sea ice properties. In particular, we address changes in sea ice export, area, and volume, as these are relevant for the Arctic Ocean freshwater budgets. The intent is to provide a quick introduction to the relevant literature for those not extremely familiar with it. Selected papers tend to address changes occurring over large spatial scales. Suggestions for additional papers to include are encouraged. A companion document (~2 pages, yet to be written) will attempt to “synthesize” these and other papers, including model studies, into a single coherent summary of recent changes in sea ice conditions and export at the pan-arctic scale.

Fram Strait Ice Export

Kwok, R. and D.A. Rothrock, Variability of Fram Strait ice flux and North Atlantic Oscillation, J. Geophys. Res., 104, 5177-5189, 1999.

Kwok and Rothrock estimate the winter ice area flux using satellite derived ice motion for 1978-1996. They find an upward trend in the ice area flux over this time period and show that the sea level pressure gradient across Fram Strait explains more than 80% of the variance in ice flux. A strong correlation between the ice flux and the positive phases of the NAO is also found.

Kwok, R., G.F. Cunningham, and S.S. Pang, Fram Strait sea ice outflow. J. Geophys. Res., 109, C01009, doi:10.1029/2003JC001785, 2004.

Kwok et al. examine a twenty-four year timeseries (1978-2002) of Fram Strait ice area export observations from satellite passive microwave data. They find that, except for extreme negative NAO years, there is a high correlation between the winter ice area export and the NAO index. From 1978-2002 there is an upward trend in the winter ice area export of 3040 km2/yr (from an average of 754,000 km2). Ice volume flux estimates are derived using a 9 year record of upward-looking sonar observations of the thickness distribution across Fram Strait. Kwok et al. indicate that inadequate sampling of the cross strait profile of ice thickness gives the largest uncertainty in the derived ice volume flux estimates. Over the nine year ice thickness record, there is a decrease of 0.45 m in the mean ice thickness across Fram Strait.

Vinje, T., Fram strait ice fluxes and atmospheric circulation: 1950-2000. J. Clim., 14, 3508-3517, 2001.

Using a parameterization that is solely dependent on the monthly mean air pressure difference across Fram Strait, Vinje obtains a time series of ice volume export from 1950-2000. The parameterization is developed using ice draft measurements from 1990- 1996, and SAR or buoy derived ice velocities. The 1950-2000 timeseries has high interannual variability, exhibits no trend in the wind-induced ice efflux and shows little correlation with the NAO winter index. For shorter periods (1978-1997) a positive correlation with the NAO is present (consistent with Kwok and Rothrock, 1999).

Ice Extent/Area Changes

Comiso, J.C., A rapidly declining perennial sea ice cover in the Arctic, Geophys. Res. Lett., 29, 1956, doi:10.1029/2002GL015650, 2002.

Comiso discusses Arctic perennial ice cover observations from satellite. He finds a decreasing trend of approximately –9% per decade from 1978-2000. Changes in summer surface temperature from satellite are strongly correlated with the perennial ice area changes.

Johannessen, O.M., E.V. Shalina, and M.W. Miles, Satellite evidence for an Arctic sea ice cover in transformation. Science, 286, 1937-1939, 1999.

Johannessen et al. discuss satellite derived timeseries of the spatially integrated area of multi-year (MY) and first-year (FY) wintertime sea ice from 1978-1998. They find that the wintertime MY ice area decreased by approximately 7% per decade over the record.

Parkinson, C.L., D.J. Cavalieri, P. Gloersen, H.J. Zwally, and J.C. Comiso, Arctic sea ice extents, areas and trends, 1978-1996, J. Geophys. Res., 104, 20,837-20,856, 1999.

Parkinson et al examine satellite passive microwave ice extents and areas from 1978- 1996 and discuss regional and seasonal trends in the ice cover. They find that there are decreasing trends in all seasons, although they are largest in spring. The largest trends are present in the Kara and Barents Seas at –10.5%/decade. There are some regions with increasing ice cover, including the Baffin Bay/Labrador Sea, the Gulf of St. Lawrence and the Bering Sea.

Serreze, M.C., J.A. Maslanik, T.A. Scambos, F. Fetterer, J. Stroeve, K. Knowles, C. Fowler, S. Drobot, R.G. Barry, and T.M. Haran, A record minimum arctic sea ice extent and area in 2002. Geophys. Res. Lett., doi:10.1029/2002GL016406, 2003.

Serreze et al discuss the record minimum sea ice year of 2002, finding that the September ice extent and area was at the lowest value in the satellite record (since 1978). They find that for 2002 anomalous warm southerly winds along the Siberian coast and persistent low pressure and warm summer temperatures were present in 2002 and suggest that these may be the forcing mechanisms responsible for the low ice conditions.

Stroeve, J.C., M.C. Serreze, F. Fetterer, T. Arbetter, W. Meier, J. Maslanik, and K. Knowles, Tracking the Arctic’s shrinking ice cover: Another extreme minimum in 2004. Geophys. Res., Lett., 32, doi:10.1029/2004GL021810, 2005. Stroeve et al. discuss recent satellite passive microwave observations of the arctic ice cover. They show that extreme September minima were present in 2002, 2003, and 2004 and claim that having three extreme minimum years in a row is unprecedented in both the satellite era (1979-present) and over the past 50 years as assessed from the HadISST1 record.

Ice Volume Changes

Rothrock, D.A., Y. Yu, and G.A. Maykut, Thinning of the Arctic sea ice cover, Geophys. Res. Lett., 26 (23), 3469-3472, 1999.

Rothrock et al. evaluated sea ice draft data from submarine upward looking sonar observations. A comparison of data averaged from 1993-1997 with data from 1958-1976 revealed that the mean ice draft at the end of the melt season has thinned dramatically. In particular they found a decrease of approximately 1.3m over much of the deep water regions of the Arctic basin from a mean of 3.1m in 1958-1976 to 1.8m in 1993-1997.

Rothrock, D.A, J. Zhang, and Y. Yu, The arctic ice thickness anomaly of the 1990s: A consistent view from observations and models, J. Geophys. Res., 108, 3038, doi:10.1029/2001JC001208, 2003.

Rothrock et al analyze sea-ice draft observations from digitally recorded data spanning the years 1987 to 1997. They find that ice draft in the western Arctic Ocean has declined substantially over this time period. Because submarine cruises sample different regions of the Arctic Ocean during different times of year, it is possible that the trends in the observed data are contaminated by sampling variations. To address this, Rothrock et al compared the observed ice draft tracks to data simulated by an ice-ocean model. They find a “compelling agreement” between the models and observations for the ice thickness decline from the late 1980s through 1997.

Wadhams, P. and N.R. Davis, Further evidence of ice thinning in the Arctic Ocean, Geophys. Res., Lett., 27, 3973-3975, 2000.

Wadhams and Davis found a 43% decrease in ice draft for a transect between Fram Strait and the North Pole from 1976 to 1996. The study compared data from two submarine cruise tracks for September of the different years.