Description: In the Amundsen Sea, warm Circumpolar Deep Water (CDW) intrudes onto the continental shelf and flows into the ice shelf cavities of the West Antarctic Ice Sheet, resulting in high basal melt rates. However, none of the high resolution global models resolving all the small ice shelves around Antarctica can reproduce a realistic CDW flow onto the Amundsen Sea continental shelf, and previous studies show simulated bottom potential temperature at the Pine Island Ice Shelf front of about −1.8 °C. In this study, using the Finite-Element Sea ice–ice shelf-Ocean Model (FESOM), we reproduce warm CDW intrusions onto the Amundsen Sea continental shelf and realistic melt rates of the ice shelves in West Antarctica. To investigate the importance of horizontal resolution, forcing, horizontal diffusivity, and the effect of grounded icebergs, eight sensitivity experiments are conducted. To simulate the CDW intrusion realistically, a horizontal resolution of about 5 km or smaller is required. The choice of forcing is also important and the cold bias in the NCEP/NCAR reanalysis over the eastern Amundsen Sea prevents warm CDW from intruding onto the continental shelf. On the other hand, the CDW intrusion is not highly sensitive to the strength of horizontal diffusion. The effect of grounded icebergs located off Bear Peninsula is minor, but may act as a buffer to an anomalously cold year.

Description: Previous studies show accelerations of West Antarctic glaciers, implying that basal melt rates of these glaciers were previously small and increased in the middle of the 20th century. This enhanced melting is a likely source of the observed Ross Sea (RS) freshening, but its long-term impact on the Southern Ocean hydrography has never been investigated. Here, we conduct coupled sea-ice/ice-shelf/ocean simulations with different levels of ice shelf melting from West Antarctic glaciers. Freshening of RS shelf and bottom water is simulated with enhanced West Antarctic ice shelf melting, while no significant changes in shelf water properties are simulated when West Antarctic ice shelf melting is small. We further show that the freshening caused by glacial meltwater from ice shelves in the Amundsen and Bellingshausen Seas propagates further downstream along the East Antarctic coast into the Weddell Sea. Our experiments also show the timescales for the freshening signal to reach other regions around the Antarctic continent. The freshening signal propagates onto the RS continental shelf within a year of model simulation, while it takes roughly 5–10 years and 10–15 years to propagate into the region off Cape Darnley and into the Weddell Sea, respectively. This advection of freshening signal} possibly modulates the properties of dense shelf water and impacts the production of Antarctic Bottom Water.

Description: In the Amundsen Sea, warm Circumpolar Deep Water (CDW) intrudes onto the continental shelf and flows into the ice shelf cavities of the West Antarctic Ice Sheet (WAIS), resulting in high basal melt rates. This affects the world ocean in two ways: First, melting of the ice sheets contributes to changes in the global sea level. Given that most of the Antarctic ice sheet drains into ice shelves, which serve as buttresses to the ice flow, variations of ice shelf basal melting are an important component in the southern hemisphere’s contribution to sea level rise. Second, ice-shelf meltwater is a freshwater source which may cause freshening of the shelf water locally in the Amundsen Sea as well as remotely in the Ross Sea. This may lead to a change in the characteristics of the Antarctic Bottom Water (AABW) formed in the Ross Sea and thus may influence the global thermohaline circulation as suggested by previous studies. Thus, investigations on possible connections between the melting of small ice shelves in West Antarctica and the large-scale ocean circulation are crucial for understanding climate change in the Southern Ocean. We study these regions using the Finite-Element Sea ice-ice shelf-Ocean Model (FESOM). Like other global models resolving all the ice shelves around Antarctica, FESOM has been unable to reproduce a realistic CDW flow onto the Amundsen Sea continental shelf. This caused large uncertainties for FESOM's present-day simulations and future projections of ice shelf basal melting. Based on an extensive suite of sensitivity studies, we have now identified the most important ingredients to a faithful representation of Amundsen Sea hydrography in ocean general circulation models. To simulate the CDW intrusion through submarine glacial troughs in a way that closely matches the observations and to obtain realistic basal melt rates for the ice shelves in West Antarctica, a horizontal resolution of about 5 km or smaller is required. The choice of atmospheric forcing data is shown to be important; a cold bias in the NCEP/NCAR reanalysis prevents warm CDW from intruding onto the continental shelf. The effect of grounded icebergs located off Bear Peninsula is minor but they may act as buffers in anomalously cold years. It has been suggested that an increased melting of continental ice in the Amundsen and Bellinghausen Seas is a likely source of the observed freshening of Ross Sea water. To test this hypothesis, we simulate the spreading of glacial melt water. Based on the spatial distribution of simulated passive meltwater tracers, most of the basal melt water from Amundsen Sea ice shelves flows towards the Ross Sea, with more than half of the meltwater originating from the Getz Ice Shelf. Sensitivity studies show that already a slight increase of the ice shelf basal mass loss can substantially intensify the transport of melt water into the Ross Sea due to a strengthening of the melt-driven shelf circulation and the westward flowing coastal current. This supports the idea that the basal melting of Amundsen/Bellingshausen Sea ice shelves contributes substantially to the observed Ross Sea freshening.

Description: It has been suggested that an increased melting of continental ice in the Amundsen Sea (AS) and Bellingshausen Sea (BS) is a likely source of the observed freshening of Ross Sea (RS) water. To test this hypothesis, we simulate the spreading of glacial meltwater using the Finite Element Sea Ice/Ice Shelf/Ocean Model. Based on the spatial distribution of simulated passive tracers, most of the basal meltwater from AS ice shelves flows toward the RS with more than half of the melt originating from the Getz Ice Shelf. Further, the model results show that a slight increase of the basal mass loss can substantially intensify the transport of meltwater into the RS due to a strengthening of the melt-driven shelf circulation and the westward flowing coastal current. This supports the idea that the basal melting of AS and BS ice shelves is one of the main sources for the RS freshening.

Description: The melting of Pine Island Ice Shelf (PIIS) has increased since the 1990 s, which may have a large impact on ice sheet dynamics, sea-level rise, and changes in water mass properties of surrounding oceans. The reason for the PIIS melting is the relatively warm (~ ∼1.2°C) Circumpolar Deep Water (CDW) that penetrates into the PIIS cavity through two submarine glacial troughs located on the Amundsen Sea continental shelf. In this study, we mainly analyze the hydrographic data obtained during ANTXXVI/3 in 2010 with the focus on pathways of the intruding CDW, PIIS melt rates, and the fate of glacial meltwater. We analyze the data by dividing CTD profiles into 6 groups according to intruding CDW properties and meltwater content. From this analysis, it is seen that CDW warmer than 1.23 °C (colder than 1.23 °C) intrudes via the eastern (central) trough. The temperature is controlled by the thickness of the intruding CDW layer. The eastern trough supports a denser CDW layer than the water mass in Pine Island Trough (PIT). The eastern intrusion is modified on the way into PIT through mixing with the lighter and colder CDW from the central trough. Using ocean transport and tracer transport calculations from the ice shelf front CTD section, the estimated melt rate in 2010 is ~ ∼30myr−1, which is comparable to published values. From spatial distributions of meltwater content, meltwater flows along the bathymetry towards the west. When compared with earlier (2000) observations, a warmer and thicker CDW layer is observed in Pine Island Trough for the period 2007–2010, indicating a recent thickening of the CDW intrusion.

Description: Previous studies show accelerations of West Antarctic glaciers, implying that basal melt rates of these glaciers were previously small and increased in the middle of the 20th century. This enhanced melting is a likely source of the observed Ross Sea (RS) freshening, but its long-term impact on the Southern Ocean hydrography has not been well investigated. Here, we conduct coupled sea ice-ice shelf-ocean simulations with different levels of ice shelf melting from West Antarctic glaciers. Freshening of RS shelf and bottom water is simulated with enhanced West Antarctic ice shelf melting, while no significant changes in shelf water properties are simulated when West Antarctic ice shelf melting is small. We further show that the freshening caused by glacial meltwater from ice shelves in the Amundsen and Bellingshausen seas can propagate further downstream along the East Antarctic coast into the Weddell Sea. The freshening signal propagates onto the RS continental shelf within a year of model simulation, while it takes roughly 5-10 and 10-15 years to propagate into the region off Cape Darnley and into the Weddell Sea, respectively. This advection of freshening modulates the shelf water properties and possibly impacts the production of Antarctic Bottom Water if the enhanced melting of West Antarctic ice shelves continues for a longer period.

Description: IFN-γ is required for cytotoxic T cell-dependent cancer genome immunoediting Nature Communications, Published online: 24 February 2017; doi:10.1038/ncomms14607 T cell mediated anti-tumour immune responses result in the emergence of an immune-resistant population in a process called immunoediting. Here, the authors show that immunoediting is associated with an increase in genomic rearrangements of tumour cells that requires both cytotoxic T cells and IFNγ exposure.

Description: The Great East Japan Earthquake: Blood Pressure Control in Patients With Chronic Kidney Disease American Journal of Hypertension 25, 951 (September 2012). doi:10.1038/ajh.2012.71 Authors: Kenichi Tanaka, Masaaki Nakayama, Yoshihiro Tani, Kimio Watanabe, Jun Asai, Yoshimitsu Hayashi, Koichi Asahi & Tsuyoshi Watanabe

Description: Journal of the American Chemical Society DOI: 10.1021/ja410696j