Japan Geoscience Union Meeting 2023

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[J] Oral

M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS08] Global climate change driven by the Southern Ocean and the Antarctic Ice Sheet

Fri. May 26, 2023 1:45 PM - 3:00 PM 103 (International Conference Hall, Makuhari Messe)

convener:Kazuya Kusahara(Japan Agency for Marine-Earth Science and Technology), Masahiro Minowa(Institute of Low Temperature Science, Hokkaido University), Yoshifumi Nogi(National Institute of Polar Research), Osamu Seki(Institute of Low Temperature Science, Hokkaido University), Chairperson:Kazuya Kusahara(Japan Agency for Marine-Earth Science and Technology)

2:15 PM - 2:30 PM

[MIS08-14] Age of bottom water in the Weddell-Enderby Basin

*Katsuro Katsumata1 (1.JAMSTEC)

Keywords:bottom water

R/V Mirai occupied a GO-SHIP meridional section I07S along 55°E in 2019/20 austral summer. The hydrograhpic section crosses eastern part of the Weddell Enderby Basin, where bottom waters from four possible sources meet, namely Adelie Land and Ross Sea Bottom Waters from the east through the Princess Elizabeth Trough, Ross Sea Deep Water advected from the west, and Cape Darnley Bottom Water from the south. The mixing ratio of these sources were estimated by the non-negative least squares fit with temperature, salinity, nutrients combined with dissolved oxygen, and planetary potential vorticity conservation. Given the mixing ratio, it was possible to estimate the age of these source waters by fitting the observed tracer concentration (CFC-11, CFC-12, CFC-113, and SF6) with assumed advection time. The estimated apparent source ages are in a range of 40 to 60 years with younger water toward the bottom and on the slope. The result is somewhat sensitive to the choice of unknown saturation rate.