Ocean Science
www.ocean-sci.net
1812-0784
1812-0792
6
1
2010
10.5194/os-6-41-2010
http://www.ocean-sci.net/6/41/2010/
http://www.ocean-sci.net/6/41/2010/os-6-41-2010.html
http://www.ocean-sci.net/6/41/2010/os-6-41-2010.pdf
41
50
2010-01-22
Indian Ocean Subtropical Mode Water: its water characteristics and spatial distribution
T. Tsubouchi
tt2r07@noc.soton.ac.uk
T. Suga
K. Hanawa
Department of Geophysics, Tohoku University, Sendai, Japan
We have improved a basic description (water characteristics and
spatial distribution) of the Indian Ocean Subtropical Mode Water
(IOSTMW) using an isopycnally averaged three-dimensional
hydrographic dataset. Two mode waters and corresponding wintertime
mixed layer depth maxima were observed north of the subtropical
front (STF) in the South Indian Ocean: IOSTMW (within
25.8–26.2 σ<sub>θ</sub>) in the region of 28–45° E
and another subtropical mode water in the subtropical gyre (within
26.4–26.7 σ<sub>θ</sub>) in the 60–80° E
longitudinal band. Through careful examination of the spatial
distribution and water characteristics of a core in the layer of
minimum vertical temperature gradient (LMVTG), we identified that a
mass of LMVTG corresponds to IOSTMW. The average water
characteristics of the IOSTMW during approximately 1960–2004 were
16.54 ± 0.49 °C, 35.51 ± 0.04 psu and
26.0 ± 0.1 σ<sub>θ</sub>. The IOSTMW distribution area
was estimated to be 25–50° E, 27–38° S. The
formation region and approximate water characteristics of the second
subtropical mode water were also estimated. Its probable formation
region was 37–42° S, 60–80° E and north of the
STF, with approximate water characteristics of
12.84 ± 0.57 °C, 35.17 ± 0.11 psu and
26.57 ± 0.04 σ<sub>θ</sub>.
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