Sea ice and snow thickness and physical properties of an ice floe in the western Weddell Sea and their changes during spring warming

Abstract

Helicopter-borne and ground-based electromagnetic (EM) ice thickness and ruler-stick snow thickness measurements as well as icecore analyses of ice temperature, salinity and texture were performed over a 5-week observation period between November 27, 2004, and January 2, 2005, on an ice floe in the western Weddell Sea at approximately 671S, 551W. The study was part of the Ice Station Polarstern (ISPOL) expedition of German research icebreaker R.V. Polarstern, investigating changes of physical, biological, and biogeochemical properties during the spring warming as a function of atmospheric and oceanic boundary conditions. The ice floe was composed of fragments of thin and thick first-year ice and thick second-year ice, with modal total thicknesses of 1.2-1.3, 2.1, and 2.4-2.9 m, respectively. This included modal snow thicknesses of 0.2-0.5 m on first-year ice and 0.75 m on second-year ice. During the observation period, snow thickness decreased by less than 0.2 m. There was hardly any ice thinning. Warming of snow and ice between 0.1 and 1.9 1C resulted in decreased ice salinity and increased brine volume. Direct current (DC) geoelectric and electromagnetic (EM) induction depth sounding were performed to study changes of electrical ice conductivity as a result of the observed ice warming. Bulk ice conductivity increased from to 37 to 97 mS/m. Analysis of conductivity anisotropy showed that the horizontal ice conductivity changed from 9 to 70 mS/m. These conductivity changes have only negligible effects on the thickness retrieval from EM measurements. Crown

Distribution and composition of dissolved extracellular polymeric substances (EPS) in Antarctic sea ice

“…The ISPOL floe was located at approximately 67 to 68°S and 55°W in the western Weddell Sea, where it was drifting in a northerly direction. This initial part of the current study represents first-and second-year ice from the structurally heterogeneous ISPOL floe (Papadimitriou et al 2007, Haas et al 2008. Details of the physical and chemical features of the floe have been reported elsewhere (Papadimitriou et al 2007, 2009, Haas et al 2008, Lannuzel et al 2008.…”

“…This initial part of the current study represents first-and second-year ice from the structurally heterogeneous ISPOL floe (Papadimitriou et al 2007, Haas et al 2008. Details of the physical and chemical features of the floe have been reported elsewhere (Papadimitriou et al 2007, 2009, Haas et al 2008, Lannuzel et al 2008. Briefly, the floe consisted of allochthonous second-year ice (200 to 250 cm thick, 80 cm snow cover) and first-year ice (150 to 180 cm thick, 30 cm snow cover), as well as autochthonous first-year ice (80 cm thick).…”

Dynamics versus Thermodynamics: The Sea Ice Thickness Distribution

“…Only then could the thermodynamic ice-albedo feedback become effi cient. Haas et al (2008c) have studied the seasonal development of surface melting in the Weddell Sea. During a 5-week drift phase as part of the Ice Station Polarstern (ISPOL) project of the German icebreaker RV Polarstern in December 2004 (Hellmer et al, 2006), snow and ice thickness changes were measured to obtain similar data as was previously available from the Arctic.…”

Antarctic sympagic meiofauna in winter: Comparing diversity, abundance and biomass between perennially and seasonally ice-covered regions

“…The Weddell Sea, in contrast, is one of the few Antarctic regions where geographic, oceanographic and meteorological conditions cause convergent sea-ice drift patterns, resulting in a perennial sea-ice cover (Brierley and Thomas, 2002). Ice concentrations in the Weddell Sea are high, large proportions of thick multi-year ice and deformed ice are found (Gordon, 1993;Haas et al, 2008Haas et al, , 2009, and the snow cover is comparatively thick (Massom et al, 2001;Haas et al, 2008;Nicolaus et al, 2009), particularly in the western regions (Willmes et al, in press). We hypothesise that these different sea-ice regimes-seasonal ice cover with young and firstyear ice on one hand, perennial ice cover with multi-year ice on the other-host different communities of sympagic (sea-ice associated) organisms.…”