Antarctic CRyosphere-Ocean System (ACROS)

The Antarctic climate system, consisting of atmosphere, ocean, and cryosphere, plays important roles in shaping the global environments such as sea level and deep ocean circulation. Observations have revealed that Ice Sheet of the West Antarctica discharges huge amount of ice mass and the speed of mass loss is accelerating. Japan has an Antarctic research base, Syowa, in the East Antarctica, whose ice mass had been believed to be stable in contrast to the West Antarctica. However, recent studies show a potential fingerprint of huge mass loss in the past and present from some regions of the East Antarctica. One of the keys of the behavior of the Ice Sheet is the supply of excess heat from the ocean and subsequent ice-ocean interaction.

The East Antarctic coast is the showcase of important and typical dynamics of the Antarctic climate system. Some continental shelf regions produce large amounts of sea ice. The active formation of sea ice leads to the production of saline and dense sea water, and recent studies have shown that the dense water here plays more important role in the global deep ocean circulation than previously considered. In Lutzow-holm Bay where Syowa Station is located, in contrast, sea ice does not generally drift away and stays for many years but the reasons for this contrast is not fully resolved. The thickened ice acts as a huge obstacle for the Shirase's approach to Syowa in recent years and hence the understating of the difference is important from logistic needs. In the past, however, the thick land-fast sea ice suddenly drifted away from the bay and open water emerged just in front of Syowa. The growth and collapse of the land-fast sea ice are said to have a periodicity of decade or two, but the mechanism of such behavior is not adequately understood.

Institute of Low Temperature Science (ILTS) has led the researches of the above mentioned behaviors and mechanisms of the ocean, sea ice, and ice sheet/glaciers. As the knowledge of each climate subsystem increases, growing attention has been paid on the interaction among these subsystems. The ILTS program Antarctic CRyosphere-Ocean System (ACROS) hence promotes and organizes the cooperation among researchers from multi-disciplinary fields and aims to contribute to ROBOTICA (Research of Ocean-ice BOundary InTeraction and Change around Antarctica) - the core program of the prioritized studies of the 9th six-year plan (2016-2022) of the Japanese Antarctic Research Expedition. With developing and implementing unmanned/automated multi-disciplinary research techniques including remotely-operated vehicles (ROVs), we explore the fields which have not been observed ever. With utilization and analysis of the satellite observation and numerical modellings, we aims at understandings of phenomena and underlying dynamics. Through organizing various workshops and researcher exchanges and promoting participation of students to the field research, we contribute to the cyrospheric science research. ACROS aims to be the program which is open to wide varieties of communities.

Schematics of ROBOTICA
Schematics of ROBOTICA


Shigeru AokiJoint Research Division
Shin SugiyamaJoint Research Division
Kay I. OhshimaJoint Research Division
Yasushi FukamachiWater and Material Cycles Division
Takenobu ToyotaWater and Material Cycles Division
Daisuke HiranoWater and Material Cycles Division
Yoshimasa MatsumuraAtmosphere and Ocean Research Institute, The University of Tokyo
Takeshi TamuraNational Institute of Polar Research


Japanese Antarctic Research Expedition

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