Investigating the Sources of Decadal-Scale Property Changes in Antarctic Bottom Water in the Southeast Indian Ocean (80-90°E)

2017 ◽  
Author(s):  
Kimberly Gottschalk
Keyword(s):  
Indian Ocean ◽  
Bottom Water ◽  
Antarctic Bottom Water ◽  
Decadal Scale ◽  
Property Changes

Recent sedimentation in the southeast Indian Ocean with special reference to the effects of Antarctic Bottom Water circulation

1978 ◽  
Vol 27 (1-2) ◽  
pp. 1-17 ◽  
Author(s):  
Venkatarathnam Kolla ◽  
Lawrence Henderson ◽  
Lawrence Sullivan ◽  
Pierre E. Biscaye
Keyword(s):  
Indian Ocean ◽  
Special Reference ◽  
Bottom Water ◽  
Water Circulation ◽  
Antarctic Bottom Water

Quaternary Antarctic Bottom-Water History: Deep-Sea Benthonic Foraminiferal Evidence from the Southeast Indian Ocean

1979 ◽  
Vol 12 (2) ◽  
pp. 271-289 ◽  
Author(s):  
Bruce H. Corliss
Keyword(s):  
Indian Ocean ◽  
Deep Sea ◽  
Bottom Water ◽  
Water Circulation ◽  
Western Boundary ◽  
Simple Relationship ◽  
Antarctic Bottom Water ◽  
Boundary Contour ◽  
Southeast Indian Ridge ◽  
Indian Ridge

Distinct assemblages of Recent deep-sea benthonic foraminifera from the southeast Indian Ocean have been shown to be associated with Antarctic Bottom Water (AABW) and Indian Bottom Water (IBW). The AABW assemblage is divided into two groups. One is dominated by Epistominella umbonifera and is associated with AABW having temperatures between −0.2° and 0.4°C. The second group is dominated by Globocassidulina subglobosa and is associated with AABW having temperatures between 0.6° and 0.8°C. The IBW assemblage is marked by the strong dominance of Uvigerina spp. and Epistominella exigua. The faunal-water-mass relationships have been used to infer the history of bottom-water circulation over the last 500,000 yr in this region using faunal data from four Eltanin cores. One core was taken from the Southeast Indian Ridge in association with IBW, and three were taken from the flank of the ridge associated with AABW flowing within a western boundary contour current in the South Australian Basin. Little faunal variation exists in the core beneath IBW (E48-22), indicating that IBW was present on the Southeast Indian Ridge during the last 300,000 yr. A record of the intensity of AABW circulation during the last 500,000 yr is inferred from the benthonic foraminiferal data in the three cores located within the western boundary contour current. Marked oscillations in the relative proportions of AABW and IBW faunal assemblages are found in one core, E48-03. The faunal variations are inferred to have resulted from variation in intensity of AABW circulation between 500,000 and 195,000 yr B.P. In E48-03, the AABW assemblage was present most of the time between 500,000 and 195,000 yr B.P., with low intensity of AABW circulation occurring primarily during the equivalent of stages 8 and 7 (t = 305,000 to 195,000 yr B.P.). The intensity of AABW circulation varied, with a maximum occurring during the equivalent of stage 11 (t = 420,000 yr B.P.). Two additional cores, E45-27 and E45–74, show relatively constant intensity of AABW circulation from 195,000 yr B.P. to the present. The intensity of AABW circulation at the present appears to be intermediate between a maximum during the equivalent of stage 11 (t = 420,000 yr B.P.) and the minimum during the equivalent of stage 8 (t = 275,000 yr B.P.). AABW production has occurred during both glacial and interglacial episodes. Bottom-water productivity has been suggested to play an important role in glacial/interglacial oscillations during the late Quaternary (Weyl, 1968; Newell, 1974). In this study, the relationship between bottom-water circulation and climatic fluctuations appears to be more complex than had been previously suggested, since a simple relationship between Quaternary bottom-water circulation and paleoclimatic fluctuations is not shown.

The flow of Antarctic bottom water to the southwest Indian Ocean estimated using CFCs

1998 ◽  
Vol 103 (C12) ◽  
pp. 27637-27653 ◽  
Author(s):  
Thomas W. N. Haine ◽  
Andrew J. Watson ◽  
Malcolm I. Liddicoat ◽  
Robert R. Dickson
Keyword(s):  
Indian Ocean ◽  
Bottom Water ◽  
Antarctic Bottom Water ◽  
Southwest Indian Ocean

scholarly journals Sensitivity of Antarctic Bottom Water to Changes in Surface Buoyancy Fluxes

2015 ◽  
Vol 29 (1) ◽  
pp. 313-330 ◽  
Author(s):  
Kate Snow ◽  
Andrew McC. Hogg ◽  
Bernadette M. Sloyan ◽  
Stephanie M. Downes
Keyword(s):  
Heat Flux ◽  
Bottom Water ◽  
Climate Models ◽  
Deep Ocean ◽  
Exchange Flow ◽  
Antarctic Bottom Water ◽  
Sector Model ◽  
Climate Change Responses ◽  
Decadal Scale ◽  
Surface Buoyancy

Abstract The influence of freshwater and heat flux changes on Antarctic Bottom Water (AABW) properties are investigated within a realistic bathymetry coupled ocean–ice sector model of the Atlantic Ocean. The model simulations are conducted at eddy-permitting resolution where dense shelf water production dominates over open ocean convection in forming AABW. Freshwater and heat flux perturbations are applied independently and have contradictory surface responses, with increased upper-ocean temperature and reduced ice formation under heating and the opposite under increased freshwater fluxes. AABW transport into the abyssal ocean reduces under both flux changes, with the reduction in transport being proportional to the net buoyancy flux anomaly south of 60°S. Through inclusion of shelf-sourced AABW, a process absent from most current generation climate models, cooling and freshening of dense source water is facilitated via reduced on-shelf/off-shelf exchange flow. Such cooling is propagated to the abyssal ocean, while compensating warming in the deep ocean under heating introduces a decadal-scale variability of the abyssal water masses. This study emphasizes the fundamental role buoyancy plays in controlling AABW, as well as the importance of the inclusion of shelf-sourced AABW within climate models in order to attain the complete spectrum of possible climate change responses.

An east-west contrasting changes of Antarctic Bottom Water properties in the Southern Indian Ocean over the last three decades

2021 ◽  
Author(s):  
Yeon Choi ◽  
SungHyun Nam
Keyword(s):  
Indian Ocean ◽  
Deep Water ◽  
Bottom Water ◽  
Ross Sea ◽  
Weddell Sea ◽  
Southern Indian Ocean ◽  
Antarctic Bottom Water ◽  
Sea Bottom ◽  
East West ◽  
Source Waters

<p>Physical properties of Antarctic Bottom Water (AABW) derived from mixture of multiple source waters of different properties, are significantly affected by and contribute to the climate change. This study reveals a contrasting east-west pattern of changes in AABW temperature and salinity in the Southern Indian Ocean (SIO), which continues to become warmer (0.04 ± 0.01<sup></sup>°C/decade) and more saline (0.002 ± 0.001 kg/g/decade) in the western SIO whereas warmer (0.03 ± 0.01<sup></sup>°C/decade) and fresher (-0.004 ± 0.001 kg/g/decade) in the eastern SIO over the past three decades, based on repeat hydrographic observations along meridional lines (1993, 1996, 2008, and 2019 in the western SIO and 1995, 2004, and 2012 in the eastern SIO). Warming and salinification of AABW consisting of the Cape Darnley Bottom Water (CDBW), Weddell Sea Deep Water (WSDW), and Lower Circumpolar Deep Water (LCDW) in the western SIO, are explained by changing proportion of source waters during the period, e.g., decreasing portion of relatively fresh CDBW (from 68% to 59%), and increasing portions of saline WSDW (from 30% to 34%) and warm and saline LCDW (from 2% to 7%). In contrast, in the eastern SIO, warming and freshening of the AABW consisting of the Ross Sea Bottom Water (RSBW), Adélie Land Bottom Water (ALBW), and LCDW are not explained by the changing proportion but properties of the source waters during the period, e.g., warming and freshening of RSBW (0.08°C/decade and -0.013 kg/g/decade) and ALBW (0.01°C/decade and -0.008 kg/g/decade). The east-west contrasting changes of AABW properties (eastern freshening and western salinification) over the last three decades have important consequences within and beyond the SIO.</p>

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