Hobart

Seminar Abstract

Tuesday 23 June, 11.30am (Tas time)
Freycinet Room, Hobart

Katsuro Katsumata
Research Institute for Global Change
JAMSTEC, Japan

Changes in Circumpolar Deep Water in the South Pacific from 1992 to 2003

Based on repeated hydrography data along Lat 32.5 deg S, we discuss changes in the Circumpolar Deep Water (CDW) from 1992 to 2003 in the South Pacific. Salinity is found decreased by 0.0018 psu on neutral surfaces, suggesting that the freshening first reported between 1968/69 and 1990/1991 is continuing at a similar rate. The freshening might be a result of the freshening of the bottom water produced off the Adelie Coast and in the Ross Sea.

A box inverse model around the Antarctica shows a reduction of the northward transport of CDW in the South Pacific. The model uses the velocity at 1000 dbar estimated from the drift data of the WOCE subsurface floats and the Argo floats as the reference. The reduced CDW transport explains the near-bottom warming during the last decade observed in this and other Pacific hydrography lines. The CDW reduction is also found in three different ocean general circulation models, one of which, being a four dimensional variational assimilation model, is capable of attributing the near-bottom warming observed in the North Pacific to the bottom water reduction around the Adelie coast.

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Location:
CSIRO = Marine Laboratories Auditorium, Castray Esplanade, Hobart

For further information, or to schedule a seminar, contact:
To schedule a seminar, contact:
Clothilde Langlais, (Oceanographic seminars) CSIRO Marine and Atmospheric Research (03) 6232 5399
Natalie Kelly, (Biology/Modelling seminars) CSIRO Marine and Atmospheric Research 0438 452 483
Jillian Enraght-Moony, (seminar administrator) CSIRO Marine and Atmospheric Research (03) 6232 5320
Communications Manager, Antarctic Climate and Ecosystems CRC (03) 6226 2265
Margaret Hazelwood, Institute of Antarctic and Southern Ocean Studies (IASOS) University of Tasmania (03) 6226 2971

Last updated 8/12/09