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Rathwell, K.J. 'She is Transforming ...': Inuit Artworks Reflect a Cultural Response to Arctic Sea Ice and Climate Change. Melnikov, V.V. Observations of Annual Walrus (Odobenus rosmarus divergens) Migrations in [...]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2009.06.009 Byline: Xavier Crosta Keywords: Diatoms; Cell cycle; Productivity; Sea ice; Southern Ocean Abstract: I here present a biometric investigation on two diatom species, Fragilariopsis kerguelensis (O'Meara) Hustedt and Fragilariopsis curta (Van Heurck) Hustedt, in Holocene samples from sediment core MD03-2601 from the Antarctic Continental Shelf off Adelie Land, East Antarctica. Apical valve length measurements of the two species are compared to their respective absolute and relative abundances as a proxy for the species productivity. Fragilariopsis kerguelensis valves were longer and more abundant during the warmer Mid-Holocene period and smaller and less abundant during the colder Late-Holocene period. Conversely, F. curta valves were smaller and less abundant during the warmer Mid-Holocene period and longer and more abundant during the colder Late-Holocene period. Mean apical valve length variations even follow centennial-to-millennial oscillations in the species abundances. Maximal valve length and minimal valve length were also larger during the warmer Mid-Holocene period and during the colder Late-Holocene period for F. keguelensis and F. curta, respectively. The observed positive size-abundance relationships are linked to the environmental conditions at the core location that stands today at the lower ecological limit for F. kerguelensis and upper ecological limit for F. curta. More favourable environmental conditions (warmer, less icy for F. kerguelensis and colder, icier for F. curta) allowed for sexual reproduction at the upper range of the sexually inducible size window and subsequent restoration of larger initial cells which, in turn, resulted in overall bigger size of the species populations, though vegetative multiplication was more frequent. Author Affiliation: UMR-CNRS 5805 EPOC, Universite Bordeaux 1, Avenue des facultes, 33405 Talence Cedex, France Article History: Received 24 March 2009; Revised 16 June 2009; Accepted 21 June 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2005.11.002 Byline: Jun Ono (a)(b), Kay I. Ohshima (b), Genta Mizuta (a), Yasushi Fukamachi (b), Masaaki Wakatsuchi (b) Abstract: To clarify the characteristics of tidal currents and heights over Kashevarov Bank (KB) in the Sea of Okhotsk, continuous mooring observation with ADCP and CT sensors was carried out near the summit of KB from 20 September 1999 to 20 June 2000. The velocity, sea-surface height, and bottom-water temperature were dominated by the diurnal signal with fortnightly modulation. The velocity amplitude reached [approximately equal to]1.4ms.sup.-1 during the spring tide. The K.sub.1 and O.sub.1 tidal current ellipses are clockwise with a nearly circular shape and nearly barotropic. To interpret the physical mechanism of the amplified diurnal currents over KB, a seamount-trapped wave (SMTW) model was applied to KB. The frequency of SMTW approximated to KB is close to the diurnal tidal frequencies for the first-gravest mode of first azimuthal wavenumber. The structure and properties of the SMTW mode are consistent with the observations. It is proposed that the amplified diurnal currents over KB are caused by the resonance with SMTW. The observed fortnightly variability in tidal currents and bottom- and surface-temperatures suggests that both the cold spot in summer and the low sea-ice concentration in winter over KB are due to the horizontal and vertical mixing with the surrounding subsurface water, caused by strong tidal currents. Author Affiliation: (a) Graduate School of Environmental Earth Science, Hokkaido University, Sapporo, Japan (b) Institute of Low Temperature Science, Hokkaido University, Sapporo, Japan Article History: Received 13 December 2004; Revised 20 September 2005; Accepted 14 November 2005

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2005.06.008 Byline: Dongseon Kim, Dong-Yup Kim, Ji-Soo Park, Young-June Kim Keywords: Time-series sediment trap; Organic carbon; Biogenic silica; Lithogenic material; Si:C ratio Abstract: Time-series sediment traps were deployed to investigate the temporal evolution of particle fluxes in the eastern Bransfield Strait over a 3-year period, from December 1998 to December 2001. Particle fluxes showed large seasonal and interannual variations. In 1999 and 2000, a seasonal trend of mass fluxes was characterized by highly elevated mass fluxes in the summer season, greater than 300mgm.sup.-2 d.sup.-1, two orders of magnitude greater than winter mass fluxes. Such high summer fluxes were not observed in 2001, however, and seasonality was also significantly reduced. The absence of a high summer flux in 2001 might have been due to an abnormal expansion of sea ice to the trap mooring site during the 2001 summer season. The large interannual variation in particle flux is closely related to annual changes in sea ice cover in the eastern Bransfield Strait, which limits phytoplankton productivity in the surface waters. There is a lag of about 1 month between the surface water productivity and the export production in the eastern Bransfield Strait. The delay in the export production might have been due to the favorable environmental conditions for phytoplankton growth in the early summer when most primary production is stored in phytoplankton biomass, and few organic particles sink into the deep ocean. An average biogenic silica:organic carbon (Si:C) ratio of 1.5 was obtained from trap material collected at a depth of 678-1034m, lower than the ratio obtained from the marginal winter sea ice zone of the Atlantic section and the Antarctic zone of the Pacific section. To produce a Si:C ratio of 1.5 at a depth of 678-1034m from the surface water ratio of 0.52, at least 65% of the surface organic carbon must be remineralized during the descent to 678-1034m. The 3-year mean of annual organic carbon fluxes measured in the eastern Bransfield Strait was 4.21[+ or -]3.16gCm.sup.-2, about two times higher than that of the central Bransfield Strait (2.84[+ or -]3.33gCm.sup.-2) and an order of magnitude higher than that of the western Bransfield Strait (0.35gCm.sup.-2). Author Affiliation: Korea Ocean Research & Development Institute, Ansan P.O. Box 29, Seoul 425-600, Republic of Korea Article History: Received 22 November 2004; Revised 9 March 2005; Accepted 14 June 2005

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2005.12.010 Byline: Lars H. Smedsrud Abstract: Vertically integrated heat content from the Weddell Sea along 69[degrees]S in vicinity of the Greenwich meridian from the 1977-2001 period is presented. This demonstrates that the east-west variability in the area is lower than the natural variability. The sensitivity on the choice of lower boundary for the heat content integral is discussed in relation to upwelling from the deeper water masses. The cooling around Maud Rise during the 1990's on the order of 20W/m.sup.2 remains significant, and may be explained by increased surface heat fluxes during winter months with lower than normal sea ice concentration. Author Affiliation: Bjerknes Centre for Climate Research, c/o Geophysical Institute, Allegaten 70, 5007 Bergen, Norway Article History: Received 25 November 2005; Accepted 16 December 2005

This paper discusses the state of the Arctic cryosphere during the second half of the twentieth century and describes major findings of observational evidence since the 1950s. Although glaciers have been retreating steadily from their Little Ice Age maximum positions for decades, Arctic sea ice extent and thickness began to decline and loss of mass from the Greenland ice sheet accelerated only in the 1990s. Rapid changes in cryospheric components have occurred in this century, affecting snow cover, Arctic sea ice extent, the mass balance of the Greenland ice sheet, and frozen ground temperatures. Projections for this century, based on model results from the Intergovernmental Panel on Climate Change, involve dramatic changes by 2100. Keywords: Arctic cryosphere, Arctic climate change, future climate., The Arctic cryosphere is undergoing unprecedented change: sea ice is shrinking and thinning, mountain glaciers and ice caps are retreating rapidly, the Greenland ice sheet is experiencing more extensive summer [...]

Meltwater from the Antarctic Ice Sheet is projected to cause up to one metre of sea-level rise by 2100 under the highest greenhouse gas concentration trajectory (RCP8.5) considered by the Intergovernmental Panel on Climate Change (IPCC). However, the effects of meltwater from the ice sheets and ice shelves of Antarctica are not included in the widely used CMIP5 climate models, which introduces bias into IPCC climate projections. Here we assess a large ensemble simulation of the CMIP5 model 'GFDL ESM2M' that accounts for RCP8.5-projected Antarctic Ice Sheet meltwater. We find that, relative to the standard RCP8.5 scenario, accounting for meltwater delays the exceedance of the maximum global-mean atmospheric warming targets of 1.5 and 2 degrees Celsius by more than a decade, enhances drying of the Southern Hemisphere and reduces drying of the Northern Hemisphere, increases the formation of Antarctic sea ice (consistent with recent observations of increasing Antarctic sea-ice area) and warms the subsurface ocean around the Antarctic coast. Moreover, the meltwater-induced subsurface ocean warming could lead to further ice-sheet and ice-shelf melting through a positive feedback mechanism, highlighting the importance of including meltwater effects in simulations of future climate.Accounting for meltwater from the Antarctic Ice Sheet in simulations of global climate leads to substantial changes in future climate projections and identifies a potential feedback mechanism that exacerbates melting., Author(s): Ben Bronselaer [sup.1] [sup.2] [sup.3] , Michael Winton [sup.2] , Stephen M. Griffies [sup.2] [sup.3] , William J. Hurlin [sup.2] , Keith B. Rodgers [sup.3] , Olga V. Sergienko [...]

Seasonally ice-covered marginal seas are among the most difficult regions in the Arctic to study. Physical constraints imposed by the variable presence of sea ice in all stages of growth [...]

The accurate design of ship routing plans in arctic areas is not easy, considering that navigation conditions (e.g., weather, visibility, and ice thickness) may change frequently. A ship's crew identifies sea ice in arctic channels with the help of radar echoes, and ship maneuvering decisions are made to avoid navigation interference. Ship officials must manually and consistently change the ship's route of travel, which is time-consuming and tedious. To address this issue, we propose a near-field route optimization model for the purpose of automatically selecting an optimal route with the help of radar echo images. The ship near-field route optimization model uses a multiobjective optimal strategy considering factors of minimum navigation risk and steaming distance. We verified the model's performance with the support of the Xuelong voyage dataset. This research finding can help a ship's crew to design more reasonable navigation routes in polar channels., Author(s): Xinwei Lin [1,2]; Shengzheng Wang (corresponding author) [2]; Xuesheng Zhang [2]; Tsung-Hsuan Hsieh [2]; Zhen Sun [2]; Tingliu Xu [2,3] 1. Introduction The thawing of ice in polar regions [...]

ABSTRACT. Ridges in sea ice and the convergent forces that form them are a serious hazard to ships traveling in the Arctic, but few studies have examined ridge distribution at [...]