Snow depth of the Weddell and Bellingshausen sea ice covers from IceBridge surveys in 2010 and 2011: An examination

We examine the snow radar data from the Weddell and Bellingshausen Seas acquired by eight IceBridge (OIB) flightlines in October of 2010 and 2011. In snow depth retrieval, the sidelobes from the stronger scattering snow-ice (s-i) interfaces could be misidentified as returns from the weaker air-snow (a-s) interfaces. In this paper, we first introduce a retrieval procedure that accounts for the structure of the radar system impulse response followed by a survey of the snow depths in the Weddell and Bellingshausen Seas. Limitations and potential biases in our approach are discussed. Differences between snow depth estimates from a repeat survey of one Weddell Sea track separated by 12 days, without accounting for variability due to ice motion, is −0.7 ± 13.6 cm. Average snow depth is thicker in coastal northwestern Weddell and thins toward Cape Norvegia, a decrease of >30 cm. In the Bellingshausen, the thickest snow is found nearshore in both Octobers and is thickest next to the Abbot Ice Shelf. Snow depth is linearly related to freeboard when freeboards are low but diverge as the freeboard increases especially in the thicker/rougher ice of the western Weddell. We find correlations of 0.71–0.84 between snow depth and surface roughness suggesting preferential accumulation over deformed ice. Retrievals also seem to be related to radar backscatter through surface roughness. Snow depths reported here, generally higher than those from in situ records, suggest dissimilarities in sample populations. Implications of these differences on Antarctic sea ice thickness are discussed.

[1]  Seymour W. Laxon,et al.  Antarctic sea ice elevation from satellite radar altimetry , 2008 .

[2]  Aqsa Patel,et al.  Signal Generation for FMCW Ultra-Wideband Radar , 2009 .

[3]  Martin O. Jeffries,et al.  Sea Ice Characteristics and Seasonal Variability of Ers‐1 Sar Backscatter in the Bellingshausen Sea , 2013 .

[4]  Stephen F. Ackley,et al.  Antarctic sea ice—A polar opposite? , 2012 .

[5]  Peter Jansen,et al.  Ultrawideband Radar Measurements of Thickness of Snow Over Sea Ice , 2007, IEEE Transactions on Geoscience and Remote Sensing.

[6]  C. Haas,et al.  Sea ice and snow thickness and physical properties of an ice floe in the western Weddell Sea and their changes during spring warming , 2008 .

[7]  K. Assmann,et al.  Amundsen Sea ice production and transport , 2005 .

[8]  Ian Allison,et al.  Snow on Antarctic sea ice , 2001 .

[9]  Chris Murphy,et al.  Beyond Point Measurements: Sea Ice Floes Characterized in 3‐D , 2013 .

[10]  S. Li,et al.  Late Winter First-Year Ice Floe Thickness Variability, Seawater Flooding and Snow Ice Formation in the Amundsen and Ross Seas , 2013 .

[11]  Prasad Gogineni,et al.  An ultra-wideband, microwave radar for measuring snow thickness on sea ice and mapping near-surface internal layers in polar firn , 2013, Journal of Glaciology.

[12]  Thomas Lavergne,et al.  A model reconstruction of the Antarctic sea ice thickness and volume changes over 1980–2008 using data assimilation , 2013 .

[13]  Stephen F. Ackley,et al.  Thickness distribution of Antarctic sea ice , 2008 .

[14]  Marcel Nicolaus,et al.  Evolution of first‐year and second‐year snow properties on sea ice in the Weddell Sea during spring‐summer transition , 2009 .

[15]  H. Jay Zwally,et al.  ICESat observations of seasonal and interannual variations of sea-ice freeboard and estimated thickness in the Weddell Sea, Antarctica (2003–2009) , 2011, Annals of Glaciology.

[16]  Christian Haas,et al.  Winter Snowcover on Sea Ice in the Weddell Sea , 1997 .

[17]  R. Colony,et al.  Observation of melt onset on multiyear Arctic sea ice using the ERS 1 synthetic aperture radar , 1994 .

[18]  Natalia Galin,et al.  Sea ice thickness, freeboard, and snow depth products from Operation IceBridge airborne data , 2013 .

[19]  Raymond A. Shaw,et al.  Crystal structure, stable isotopes (δ18O), and development of sea ice in the Ross, Amundsen, and Bellingshausen seas, Antarctica , 1994 .

[20]  Mark R. Drinkwater,et al.  ERS 1 radar and field‐observed characteristics of autumn freeze‐up in the Weddell Sea , 1997 .

[21]  M. Jeffries,et al.  The thickness distribution of sea ice and snow cover during late winter in the Bellingshausen and Amundsen Seas, Antarctica , 1996 .

[22]  Stephen F. Ackley,et al.  Sea ice and snow cover characteristics during the winter-spring transition in the Bellingshausen Sea: An overview of SIMBA 2007 , 2011 .

[23]  S. Gogineni,et al.  Airborne Radar for Measuring Snow Thickness over Sea Ice , 2006 .

[24]  Thorsten Markus,et al.  Evaluation of AMSR‐E snow depth product over East Antarctic sea ice using in situ measurements and aerial photography , 2008 .

[25]  Matthew Sturm,et al.  The Winter Snow Cover of the West Antarctic Pack Ice: Its Spatial and Temporal Variability , 2013 .

[26]  J. Turner,et al.  An Initial Assessment of Antarctic Sea Ice Extent in the CMIP5 Models , 2013 .

[27]  Stephen F. Ackley,et al.  Sea ice thickness retrieval algorithms based on in situ surface elevation and thickness values for application to altimetry , 2013 .

[28]  S. Stammerjohn,et al.  West Antarctic Peninsula sea ice in 2005: Extreme ice compaction and ice edge retreat due to strong anomaly with respect to climate , 2008 .

[29]  Thorsten Markus,et al.  A First Assessment of IceBridge Snow and Ice Thickness Data Over Arctic Sea Ice , 2012, IEEE Transactions on Geoscience and Remote Sensing.

[30]  Ted Maksym,et al.  Freeboard, snow depth and sea-ice roughness in East Antarctica from in situ and multiple satellite data , 2011, Annals of Glaciology.

[31]  Ron Kwok,et al.  Arctic sea ice freeboard from IceBridge acquisitions in 2009: Estimates and comparisons with ICESat , 2012 .

[32]  R. Kwok,et al.  Airborne surveys of snow depth over Arctic sea ice , 2011 .

[33]  Michael Studinger,et al.  Polar Airborne Observations Fill Gap in Satellite Data , 2010 .

[34]  P. Wadhams,et al.  Characteristics and distribution patterns of snow and meteoric ice in the Weddell Sea and their contribution to the mass balance of sea ice , 1994 .

[35]  Jinlun Zhang,et al.  Modeling the Impact of Wind Intensification on Antarctic Sea Ice Volume , 2014 .

[36]  Robert N. Swift,et al.  Aircraft laser altimetry measurement of elevation changes of the greenland ice sheet: technique and accuracy assessment , 2002 .

[37]  Nathan T. Kurtz,et al.  Large‐scale surveys of snow depth on Arctic sea ice from Operation IceBridge , 2011 .

[38]  W. R. Fraser,et al.  Extreme Anomalous Atmospheric Circulation in the West Antarctic Peninsula Region in Austral Spring and Summer 2001/02, and Its Profound Impact on Sea Ice and Biota* , 2006 .

[39]  Ross M. McConnell,et al.  An ice-motion tracking system at the Alaska SAR facility , 1990 .

[40]  T. Maksym,et al.  The importance of wind-blown snow redistribution to snow accumulation on Bellingshausen Sea ice , 2011, Annals of Glaciology.

[41]  Thorsten Markus,et al.  Satellite Observations of Antarctic Sea Ice Thickness and Volume , 2012 .

[42]  T. Maksym,et al.  A one‐dimensional percolation model of flooding and snow ice formation on Antarctic sea ice , 2000 .

[43]  Stephen F. Ackley,et al.  Sea ice thickness estimations from ICESat Altimetry over the Bellingshausen and Amundsen Seas, 2003–2009 , 2012 .

[44]  Ted Maksym,et al.  Antarctic Sea Ice Thickness and Snow-to-Ice Conversion from Atmospheric Reanalysis and Passive Microwave Snow Depth , 2008 .

[45]  Robert Cullen,et al.  Ku-band radar penetration into snow cover on Arctic sea ice using airborne data , 2011, Annals of Glaciology.