Article
Geosciences, Multidisciplinary
K. Nakata, K. I. Ohshima, S. Nihashi
Summary: Recent in situ and high-resolution satellite observations have highlighted the importance of active frazil and associated high sea-ice production in Antarctic coastal polynyas. The spatial distribution of active-frazil area, predominantly found along East Antarctica, is influenced by offshore wind and air temperature, while ice production is mainly determined by offshore wind. This study presents the first mapping of active-frazil area for Antarctic coastal polynyas, with ice production rates exceeding 20 m/yr in some areas.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Environmental Sciences
Genta Mizuta, Yasushi Fukamachi, Daisuke Simizu, Yoshimasa Matsumura, Yujiro Kitade, Daisuke Hirano, Masakazu Fujii, Yoshifumi Nogi, Kay Ohshima
Summary: This study investigated the seasonal evolution of Cape Darnley Bottom Water (CDBW) using mooring and hydrographic measurements conducted in 2008-2009 and 2013-2014. The newly formed CDBW showed varying potential temperature and salinity properties as it spread from the western to eastern parts of the slope region off Cape Darnley. It is likely that the seasonal variations in CDBW properties are influenced by the accumulation of brine in the Cape Darnley polynya during the ice production season.
FRONTIERS IN MARINE SCIENCE
(2021)
Article
Engineering, Marine
Felix Paul, Tommy Mielke, Carina Schwarz, Joerg Schroeder, Tokoloho Rampai, Sebastian Skatulla, Riesna R. Audh, Ehlke Hepworth, Marcello Vichi, Doru C. Lupascu
Summary: Frazil ice, the first ice forming in the annual cycle in the Marginal Ice Zone (MIZ) of the Antarctic, consists of loose disc-shaped ice crystals and plays a fundamental role in the freezing processes by forming the surface grease ice layer. The rheological properties of frazil ice, including shear thinning flow behavior, have a crucial influence on the growth of sea ice in the MIZ, and real-data-founded measurements enable modeling of the annual ice cycle.
JOURNAL OF MARINE SCIENCE AND ENGINEERING
(2021)
Article
Oceanography
Libao Gao, Yongcan Zu, Guijun Guo, Saisai Hou
Summary: This study analyzes hydrographic CTD and float data collected from the southwest Indian Ocean sector of the Antarctic margin between 2003 and 2020 to investigate the distribution, pathway, and changes of newly-formed Cape Darnley Bottom Water (CDBW). The results show that CDBW appears primarily on the continental slope and abyssal ocean in the eastern Cooperation Sea, with high fractions in the bottom 300 m. The formation of CDBW is influenced by factors such as sea ice production and cascading Dense Shelf Water plumes.
DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY
(2022)
Article
Oceanography
K. Nakata, K. Ohshima
Summary: Frazil ice in coastal polynyas is important for sea ice production and biological production. This study presents the first mapping of active frazil in the Northern Hemisphere and improves estimates of sea ice production. It is found that the Antarctic coastal polynyas have higher ice production and active frazil occurrence compared to the Northern Hemisphere largely due to stronger wind events.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2022)
Article
Geosciences, Multidisciplinary
Wilton Aguiar, Sang-Ki Lee, Hosmay Lopez, Shenfu Dong, Helene Seroussi, Dani C. Jones, Adele K. Morrison
Summary: Melting of the ice sheet in the Southern Ocean has implications for the formation and properties of the Antarctic Bottom Water (AABW). Models have been used to examine the effects of different spatial distributions and magnitudes of meltwater fluxes on AABW. The study finds that a realistic and spatially varying meltwater flux can sustain AABW with higher salinities compared to uniform meltwater flux simulations. Furthermore, the increasing meltwater discharge from the Antarctic ice sheet can contribute to the observed freshening of AABW.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Engineering, Environmental
Zhikun Chen, Maria Elektorowicz, Chunjiang An, Xuelin Tian
Summary: Sea ice can act as a temporary sink and transport medium for microplastics, and the entrainment and enrichment of microplastics in ice are influenced by various properties and environmental characteristics. High rotation speed in freshwater enhances the entrainment of hydrophobic microplastics, while high turbulence in saline water inhibits the entrainment of all microplastic types. This study highlights the critical pathways of microplastics' fate in cold regions.
ENVIRONMENTAL SCIENCE & TECHNOLOGY
(2023)
Article
Oceanography
Joshua Coupe, Cheryl Harrison, Alan Robock, Alice DuVivier, Elizabeth Maroon, Nicole S. Lovenduski, Scott Bachman, Laura Landrum, Charles Bardeen
Summary: A large-scale nuclear war could lead to rapid global climate change due to the injection of soot into the stratosphere. In climate model simulations, global cooling causes expansion of sea ice in the Northern Hemisphere, but in the Southern Hemisphere, sea ice initially expands and then suddenly loses 30% of its volume in a single melting season in the largest nuclear war simulation.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2023)
Article
Geosciences, Multidisciplinary
Ruth Moorman, Andrew F. Thompson, Earle A. Wilson
Summary: The melt rates of West Antarctic ice shelves in the Amundsen Sea are influenced by decadal variations in the volume of warm water at their outlets, which are generally attributed to wind-driven variations in warm water transport. However, this study introduces a simple model that suggests interannual variations in coastal polynya buoyancy forcing can also generate large decadal-scale variations in thermocline depth, even with a fixed supply of warm water from the shelf-break. This model demonstrates feedbacks between basal melt rates and ice front stratification strength, capturing observed variations in near-coast thermocline depth and stratification strength, and proposing an alternative mechanism for warm water volume changes compared to wind-driven theories.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Environmental Sciences
Lucie Bourreau, Etienne Pauthenet, Loic Le Ster, Baptiste Picard, Esther Portela, Jean-Baptiste Sallee, Clive R. McMahon, Robert Harcourt, Mark Hindell, Christophe Guinet, Sophie Bestley, Jean-Benoit Charrassin, Alice DuVivier, Zephyr Sylvester, Kristen Krumhardt, Stephanie Jenouvrier, Sara Labrousse
Summary: This study investigates the in situ chlorophyll fluorescence signal in Antarctic coastal polynyas during winter and identifies its main oceanographic drivers. The results show a significant fluorescence signal from February to April, with an additional signal in certain locations in August. The fluorescence signal was found to be associated with changes in water depth, mixed layer depth, water temperature, and salinity.
FRONTIERS IN MARINE SCIENCE
(2023)
Article
Geosciences, Multidisciplinary
Ricarda Nielsen, Gabriele Uenzelmann-Neben
Summary: Studying the paleo-conditions of CDBW can provide insights into the formation of saline lakes and the transition between greenhouse and icehouse states during the middle to late Miocene.
Article
Meteorology & Atmospheric Sciences
Xiaoyi Shen, Chang-Qing Ke, Bin Cheng, Wentao Xia, Mengmeng Li, Xuening Yu, Haili Li
Summary: In August 2018, a remarkable polynya was observed off the north coast of Greenland, formed due to the thinnest sea ice cover and modest southerly wind caused by a positive North Atlantic Oscillation. The opening mechanism of this polynya differs from the one formed in the same area in February 2018, with sea ice drift patterns becoming more responsive to atmospheric forcing due to thinning of sea ice cover in this region.
ADVANCES IN ATMOSPHERIC SCIENCES
(2021)
Article
Geography, Physical
Siobhan Johnson, Riesna R. Audh, Wayne de Jager, Boitumelo Matlakala, Marcello Vichi, Ashleigh Womack, Tokoloho Rampai
Summary: This study presents the first dataset of physical and textural properties of sea ice collected in the Antarctic marginal ice zone (MIZ) in the South Atlantic and Indian Ocean sector. The observations of sea ice from this region were used to reconstruct synoptic conditions and study the stratigraphic properties of consolidated pack ice samples. The study found significant differences in the stratigraphy between the eastward and westward groups of samples, indicating the influence of atmospheric and sea-ice conditions on the stratigraphic properties of Antarctic sea-ice floes.
JOURNAL OF GLACIOLOGY
(2023)
Article
Oceanography
Stephanie M. Lim, Gert L. van Dijken, Kevin R. Arrigo
Summary: This study investigated the response of Antarctic ice algal habitat to variations in sea ice and other environmental forcings. The research found that the Antarctic has a larger extent and duration of potential ice algal habitat than the Arctic. The bottom ice melt date was identified as the most important factor in explaining the variation in ice algal habitat. The study suggests that Antarctic ice algal habitat may be highly sensitive to future climate changes.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2023)
Article
Environmental Sciences
Saisai Hou, Jiuxin Shi
Summary: This study identifies four recurrent polynyas in eastern Prydz Bay and shows that these polynyas are primarily wind-driven, requiring at least one stationary ice barrier to block the inflow of drifting sea ice.
Article
Oceanography
Kay Ohshima, Naoya Tamaru, Haruhiko Kashiwase, Sohey Nihashi, Kazuki Nakata, Katsushi Iwamoto
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2020)
Article
Oceanography
S. Aoki, K. Katsumata, M. Hamaguchi, A. Noda, Y. Kitade, K. Shimada, D. Hirano, D. Simizu, Y. Aoyama, K. Doi, Y. Nogi
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2020)
Article
Multidisciplinary Sciences
Daisuke Hirano, Takeshi Tamura, Kazuya Kusahara, Kay I. Ohshima, Keith W. Nicholls, Shuki Ushio, Daisuke Simizu, Kazuya Ono, Masakazu Fujii, Yoshifumi Nogi, Shigeru Aoki
NATURE COMMUNICATIONS
(2020)
Article
Geosciences, Multidisciplinary
K. Nakata, K. I. Ohshima, S. Nihashi
Summary: Recent in situ and high-resolution satellite observations have highlighted the importance of active frazil and associated high sea-ice production in Antarctic coastal polynyas. The spatial distribution of active-frazil area, predominantly found along East Antarctica, is influenced by offshore wind and air temperature, while ice production is mainly determined by offshore wind. This study presents the first mapping of active-frazil area for Antarctic coastal polynyas, with ice production rates exceeding 20 m/yr in some areas.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Environmental Sciences
Masaaki Kiuchi, Daiki Nomura, Daisuke Hirano, Takeshi Tamura, Gen Hashida, Shuki Ushio, Daisuke Simizu, Kazuya Ono, Shigeru Aoki
Summary: The study focused on the impact of basal melting of ice tongues/ice shelf on the CO2 system in the Antarctic continental margin by analyzing seawater samples collected at the ice front of the Shirase Glacier Tongue in East Antarctica. Results showed that the dilution effect of SGT basal melting and the inflow of modified Circumpolar Deep Water significantly influenced the CO2 system parameters in the area, reducing the partial pressure of CO2 in the modified Circumpolar Deep Water. Additionally, biological processes strongly affected DIC and TA at the sea surface, with a high concentration of chl.a observed.
JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES
(2021)
Article
Geosciences, Multidisciplinary
Yoshihiro Nakayama, Chad A. Greene, Fernando S. Paolo, Vigan Mensah, Hong Zhang, Haruhiko Kashiwase, Daisuke Simizu, Jamin S. Greenbaum, Donald D. Blankenship, Ayako Abe-Ouchi, Shigeru Aoki
Summary: Research suggests that the Antarctic Slope Current (ASC) plays a blocking role in intrusions of warm modified Circumpolar Deep Water (mCDW) towards the Totten ice shelf (TIS) region, with weakening of the ASC leading to enhanced on-shelf intrusions. Additionally, heat intrusions onto the TIS continental shelf are not influenced by off-shelf warming but rather by coastal freshening, indicating a positive feedback mechanism where ice melt and freshening upstream could trigger a chain reaction of increased melt and further coastal freshening.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Environmental Sciences
Genta Mizuta, Yasushi Fukamachi, Daisuke Simizu, Yoshimasa Matsumura, Yujiro Kitade, Daisuke Hirano, Masakazu Fujii, Yoshifumi Nogi, Kay Ohshima
Summary: This study investigated the seasonal evolution of Cape Darnley Bottom Water (CDBW) using mooring and hydrographic measurements conducted in 2008-2009 and 2013-2014. The newly formed CDBW showed varying potential temperature and salinity properties as it spread from the western to eastern parts of the slope region off Cape Darnley. It is likely that the seasonal variations in CDBW properties are influenced by the accumulation of brine in the Cape Darnley polynya during the ice production season.
FRONTIERS IN MARINE SCIENCE
(2021)
Review
Oceanography
Daisuke Hirano, Yasushi Fukamachi, Kay Ohshima, Masato Ito, Takeshi Tamura, Daisuke Simizu, Toru Takatsuka, Andrew R. Mahoney, Joshua Jones, Craig George, Billy Adams, Hajo Eicken
Summary: The study confirms that the Barrow Coastal Polynya (BCP) is a wind-driven polynya dominated by interannual variability. The presence of warm water delays freeze onset and influences heat transport in the Chukchi Shelf and Arctic basin.
PROGRESS IN OCEANOGRAPHY
(2022)
Article
Oceanography
Reishi Sahashi, Daiki Nomura, Takenobu Toyota, Manami Tozawa, Masato Ito, Pat Wongpan, Kazuya Ono, Daisuke Simizu, Kazuhiro Naoki, Yuichi Nosaka, Takeshi Tamura, Shigeru Aoki, Shuki Ushio
Summary: This study investigated the effects of snow and remineralization processes on nutrient distributions in multi-year landfast sea ice in Lutzow-Holm Bay, East Antarctica. It was found that the upward growth of the multi-year fast ice was attributed to the accumulation of snow over the years. Nutrient concentrations were lower in the shallow ice due to the replacement by clean and fresh snow, while remineralization dominated in the deeper ice from seawater origin. Additionally, the biological uptake was more dominant in relatively young ice, whereas older ice was more prone to remineralization under the physical process of brine drainage.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2022)
Article
Environmental Sciences
Shigeru Aoki, Tomoki Takahashi, Kaihe Yamazaki, Daisuke Hirano, Kazuya Ono, Kazuya Kusahara, Takeshi Tamura, Guy D. Williams
Summary: Melting ice shelves play a crucial role in the input of freshwater into the ocean and global heat redistribution. In summer 2016/17, the coastal ocean around Antarctica had almost no sea-ice, resulting in higher surface water temperatures. The glacial meltwater fraction in surface water reached a record high, likely due to abnormal ice shelf melting. The excess heat and freshwater delayed the seasonal formation of dense shelf water in early 2017.
COMMUNICATIONS EARTH & ENVIRONMENT
(2022)