Antarctic Intermediate Water circulation in the tropical and subtropical South Atlantic

1995 ◽  
Vol 100 (C7) ◽  
pp. 13441 ◽  
Author(s):  
Toshio Suga ◽  
Lynne D. Talley
Keyword(s):  
South Atlantic ◽  
Water Circulation ◽  
Intermediate Water ◽  
Antarctic Intermediate Water

scholarly journals Antarctic intermediate water circulation in the South Atlantic over the past 25,000 years

2016 ◽  
Vol 31 (10) ◽  
pp. 1302-1314 ◽  
Author(s):  
Jacob N. W. Howe ◽  
Alexander M. Piotrowski ◽  
Delia W. Oppo ◽  
Kuo-Fang Huang ◽  
Stefan Mulitza ◽  
...  
Keyword(s):  
South Atlantic ◽  
Water Circulation ◽  
Intermediate Water ◽  
The South ◽  
Antarctic Intermediate Water ◽  
The Past

scholarly journals Freshening of Antarctic Intermediate Water in the South Atlantic Ocean in 2005–2014

2016 ◽  
Author(s):  
Wenjun Yao ◽  
Jiuxin Shi
Keyword(s):  
Atlantic Ocean ◽  
Ocean Circulation ◽  
Hydrological Cycle ◽  
World Ocean ◽  
South Atlantic ◽  
South Atlantic Ocean ◽  
Intermediate Water ◽  
Freshwater Input ◽  
The South ◽  
Antarctic Intermediate Water

Abstract. Basin-scaled freshening of Antarctic Intermediate Water (AAIW) is reported to have dominated South Atlantic Ocean during period from 2005 to 2014, as shown by the gridded monthly means Argo (Array for Real-time Geostrophic Oceanography) data. The relevant investigation was also revealed by two transatlantic occupations of repeated section along 30° S, from World Ocean Circulation Experiment Hydrographic Program. Freshening of the AAIW was compensated by the opposing salinity increase of thermocline water, indicating the contemporaneous hydrological cycle intensification. This was illustrated by the precipitation less evaporation change in the Southern Hemisphere from 2000 to 2014, with freshwater input from atmosphere to ocean surface increasing in the subpolar high-precipitation region and vice versa in the subtropical high-evaporation region. Against the background of hydrological cycle augment, the decreased transport of Agulhas Leakage (AL) was proposed to be one of the contributors for the associated freshening of AAIW. This indirectly estimated variability of AL, reflected by the weakening of wind stress over the South Indian Ocean since the beginning of 2000s, facilitates the freshwater input from source region and partly contributes to the observed freshened AAIW. Both of our mechanical analysis is qualitative, but this work would be helpful to validate and test predictably coupled sea-air model simulations.

scholarly journals The Adjustment of the Coupled Climate Model HadGEM1 toward Equilibrium and the Impact on Global Climate

2007 ◽  
Vol 20 (23) ◽  
pp. 5815-5826 ◽  
Author(s):  
Helene T. Banks ◽  
Sheila Stark ◽  
Ann B. Keen
Keyword(s):  
Surface Temperature ◽  
Climate Models ◽  
Climate Model ◽  
South Atlantic ◽  
Shortwave Radiation ◽  
Intermediate Water ◽  
Antarctic Intermediate Water ◽  
Adjustment Time ◽  
Coupled Climate Models ◽  
The Impact

Abstract Coupled climate models generally have a small residual radiative flux at the top of the atmosphere. In the Met Office climate model, Hadley Centre Global Environmental Model version 1 (HadGEM1), it is incoming (heating the planet) and reduces over a 350-yr period from 0.4 to 0.1 W m−2. The process of the adjustment in HadGEM1 is examined and is shown to be linked to excessive heat gain. In the tropical and South Atlantic, cold, fresh Antarctic Intermediate Water is replaced by anomalously warm, salty intermediate water. The loss of Antarctic Intermediate Water in the South Atlantic is related to a weak Agulhas retroflection. The erosion is enhanced in the tropical Atlantic by strong upwelling. The warm, salty anomalies are advected northward outcropping in the North Atlantic subpolar gyre. In the outcrop zone, sea surface temperature and salinity are increased, which lead to an increase in global mean surface temperature and a reduction in the sea ice area. This adjusts the top of the atmosphere balance via increased outgoing longwave radiation and is partly offset by a decrease in outgoing shortwave radiation. The increased surface salinity triggers convection in the Labrador Sea and leads to a strong flushing of the thermohaline circulation. These results demonstrate that adjustment time scales for coupled climate models can be in excess of 350 yr. The potential implications of the adjustment time scale of climate models need to be considered when planning scenario and sensitivity experiments, as model drifts can be nonlinear.

scholarly journals Freshening of Antarctic Intermediate Water in the South Atlantic Ocean in 2005–2014

Ocean Science ◽  
2017 ◽  
Vol 13 (4) ◽  
pp. 521-530 ◽  
Author(s):  
Wenjun Yao ◽  
Jiuxin Shi ◽  
Xiaolong Zhao
Keyword(s):  
Atlantic Ocean ◽  
Hydrological Cycle ◽  
World Ocean ◽  
South Atlantic ◽  
South Atlantic Ocean ◽  
Intermediate Water ◽  
Freshwater Input ◽  
The South ◽  
Antarctic Intermediate Water ◽  
Basin Scale

Abstract. Basin-scale freshening of Antarctic Intermediate Water (AAIW) is reported to have occurred in the South Atlantic Ocean during the period from 2005 to 2014, as shown by the gridded monthly means of the Array for Real-time Geostrophic Oceanography (Argo) data. This phenomenon was also revealed by two repeated transects along a section at 30° S, performed during the World Ocean Circulation Experiment Hydrographic Program. Freshening of the AAIW was compensated for by a salinity increase of thermocline water, indicating a hydrological cycle intensification. This was supported by the precipitation-minus-evaporation change in the Southern Hemisphere from 2000 to 2014. Freshwater input from atmosphere to ocean surface increased in the subpolar high-precipitation region and vice versa in the subtropical high-evaporation region. Against the background of hydrological cycle changes, a decrease in the transport of Agulhas Leakage (AL), which was revealed by the simulated velocity field, was proposed to be a contributor to the associated freshening of AAIW. Further calculation showed that such a decrease could account for approximately 53 % of the observed freshening (mean salinity reduction of about 0.012 over the AAIW layer). The estimated variability of AL was inferred from a weakening of wind stress over the South Indian Ocean since the beginning of the 2000s, which would facilitate freshwater input from the source region. The mechanical analysis of wind data here was qualitative, but it is contended that this study would be helpful to validate and test predictably coupled sea–air model simulations.

Sign in / Sign up

Export Citation Format

Share Document