Growth, properties and relation to radar backscatter coefficient of sea ice in Lützow-Holm Bay, Antarctica

Abstract Based on studies in the Antarctic Oceans, the contribution of the snow cover to sea-ice growth has become of major interest. Snow can result in upward ice growth in contrast with ordinary downward congelation growth at the bottom. A sea-ice study was conducted to verify the upward ice growth found in a previous study and to investigate the relation between sea-ice growth and radar backscattering signature. Sea-ice samples collected at four points in Lützow-Holm Bay, Antarctica, from 1998 to 2003 are analyzed. Analyses of snow-/ice-gauge measurements, snow depth and ice structure reveal an extremely large amount of upward ice growth of up to 1.0 m during one full year compared with a slight amount of downward growth. The upward growth was caused mostly by snow ice and to a lesser extent by superimposed ice. The salinity profile remained unchanged, although the ice survived the summer melt season. Characteristics of superimposed ice such as salinity, δ18O values and structure were obliterated during the summer, implying complete melting or dissolution of the superimposed layer. The ERS-2 backscatter showed a remarkable annual variation: It had a minimum value in midsummer and increased abruptly to a maximum value in late summer, then decreasing gradually in wintertime. The relation of the backscatter coefficient to the growth and properties of the snow cover and sea ice are discussed.

[1]  J. Tison,et al.  Superimposed-ice formation in summer on Ross Sea pack-ice floes , 2004, Annals of Glaciology.

[2]  C. Haas,et al.  Surface properties and processes of perennial Antarctic sea ice in summer , 2001, Journal of Glaciology.

[3]  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 .

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

[5]  A. S. Bennett,et al.  Conversion of in situ measurements of conductivity to salinity , 1976 .

[6]  Christian Haas,et al.  The seasonal cycle of ERS scatterometer signatures over perennial Antarctic sea ice and associated surface ice properties and processes , 2001, Annals of Glaciology.

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

[8]  Shuki Ushio,et al.  Factors affecting fast-ice break-up frequency in Lützow-Holm Bay, Antarctica , 2006, Annals of Glaciology.

[9]  R. M. Koerner,et al.  Some Observations on Superimposition of Ice on the Devon Island Ice Cap, N.W.T. Canada , 1970 .

[10]  A Oy,et al.  Synthetic Aperture Radar Calibration Using Reference Reflectors , 1990 .

[11]  H. Eicken,et al.  Spatial variability of sea‐ice properties in the northwestern Weddell Sea , 1991 .

[12]  D. Notz,et al.  Impact of underwater‐ice evolution on Arctic summer sea ice , 2003 .

[13]  D. Barber,et al.  An examination of the relation between the spring period evolution of the scattering coefficient (σ) and radiative fluxes over Jandfast sea-ice , 1995 .

[14]  Stephen F. Ackley,et al.  18O Concentrations In Sea Ice Of The Weddell Sea, Antarctica , 1990, Journal of Glaciology.

[15]  Stephen F. Ackley,et al.  The Growth, Structure, and Properties of Sea Ice , 1982 .

[16]  Seasonal variations in the properties and structural composition of sea ice and snow cover in the Bellingshausen and Amundsen Seas, Antarctica , 1997 .

[17]  Hajo Eicken,et al.  Development and properties of sea ice in the coastal regime of the southeastern Weddell Sea , 1989 .

[18]  H. Eicken,et al.  Textural characteristics of sea ice and the major mechanisms of ice growth in the Weddell Sea , 1991, Annals of Glaciology.

[19]  K. Ohshima,et al.  Physical, structural, and isotopic characteristics and growth processes of fast sea ice in Lützow‐Holm Bay, Antarctica , 1997 .