scholarly journals Variability of the South Pacific Western Subtropical Mode Water and Its Relationship With ENSO During the Argo Period

2020 ◽  
Vol 125 (8) ◽  
Author(s):  
Jifeng Qi ◽  
Tangdong Qu ◽  
Baoshu Yin ◽  
Jianwei Chi
Keyword(s):  
South Pacific ◽  
The South ◽  
Mode Water ◽  
Subtropical Mode Water

scholarly journals Structure and Modification of the South Pacific Eastern Subtropical Mode Water

2009 ◽  
Vol 39 (7) ◽  
pp. 1700-1714 ◽  
Author(s):  
Kanako Sato ◽  
Toshio Suga
Keyword(s):  
Potential Vorticity ◽  
South Pacific ◽  
The South ◽  
Mode Water ◽  
Argo Data ◽  
Formation Region ◽  
Subtropical Mode Water ◽  
Vertical Changes ◽  
Salt Fingering ◽  
Vertical Gradients

Abstract Using all available temperature and salinity profiles obtained by Argo floats from July 2004 to June 2007, this study investigated the structure and modification of the South Pacific Eastern Subtropical Mode Water (SPESTMW). Based on the observed characteristics of the vertical minima of potential vorticity over the subtropical South Pacific, SPESTMW is defined as water with potential vorticity magnitude less than 2.5 × 10−10 m−1 s−1 and thickness exceeding 40 m. It is found between 35°–5°S and 160°–70°W and has a temperature of 13°–26°C, salinity greater than 34.0, and density of 24.5–25.8 kg m−3 at its core. This study confirmed that vertical changes in temperature and salinity tend to compensate for each other in terms of density changes, resulting in favorable salt fingering conditions, as previously reported. By analyzing many profiles of Argo data in spring immediately after the SPESTMW formation period, its temperature and salinity are vertically uniform in the formation region, but large vertical gradients of temperature and salinity are found downstream from that region, even in the SPESTMW core. Consequently, the low potential vorticity signature of SPESTMW spread much wider than its signature as a thermostad. The Argo data also captured the seasonal changes of the vertical gradients of temperature and salinity at the SPESTMW core; these gradients increased as the seasons progressed, even in the formation region. Therefore, SPESTMW is truly vertically uniform water (i.e., thermostad, halostad, and pycnostad simultaneously) only immediately after the formation period. Afterward, it is only pycnostad. This seasonal evolution is related to temperature and salinity diffusion due to salt fingering in a manner similar to the rapid modification of interannual anomalies as shown by previous research. The temperature and salinity near the SPESTMW core and lower region decreased soon after its formation.

The South Pacific Subtropical Mode Water in the Tasman Sea

2007 ◽  
Vol 6 (2) ◽  
pp. 107-116 ◽  
Author(s):  
Haibo Hu ◽  
Qinyu Liu ◽  
Xiaopei Lin ◽  
Wei Liu
Keyword(s):  
South Pacific ◽  
The South ◽  
Mode Water ◽  
Subtropical Mode Water ◽  
Tasman Sea

On the influence of Subtropical Mode Water on the South Atlantic Ocean

2018 ◽  
Vol 185 ◽  
pp. 13-24 ◽  
Author(s):  
Arthur Gerard Quadros de Souza ◽  
Rodrigo Kerr ◽  
José Luiz Lima de Azevedo
Keyword(s):  
Atlantic Ocean ◽  
South Atlantic ◽  
South Atlantic Ocean ◽  
The South ◽  
Mode Water ◽  
Subtropical Mode Water

scholarly journals Origin and Pathway of Equatorial 13°C Water in the Pacific Identified by a Simulated Passive Tracer and Its Adjoint*

2009 ◽  
Vol 39 (8) ◽  
pp. 1836-1853 ◽  
Author(s):  
Tangdong Qu ◽  
Shan Gao ◽  
Ichiro Fukumori ◽  
Rana A. Fine ◽  
Eric J. Lindstrom
Keyword(s):  
General Circulation ◽  
Circulation Model ◽  
South Pacific ◽  
Equatorial Region ◽  
Equatorial Pacific ◽  
Western Boundary ◽  
Passive Tracer ◽  
The South ◽  
Mode Water ◽  
Eastern Equatorial Pacific

Abstract The origin and pathway of the thermostad water in the eastern equatorial Pacific Ocean, often referred to as the equatorial 13°C Water, are investigated using a simulated passive tracer and its adjoint, based on circulation estimates of a global general circulation model. Results demonstrate that the source region of the 13°C Water lies well outside the tropics. In the South Pacific, some 13°C Water is formed northeast of New Zealand, confirming an earlier hypothesis on the water’s origin. The South Pacific origin of the 13°C Water is also related to the formation of the Eastern Subtropical Mode Water (ESTMW) and the Sub-Antarctic Mode Water (SAMW). The portion of the ESTMW and SAMW that eventually enters the density range of the 13°C Water (25.8 < σθ < 26.6 kg m−3) does so largely by mixing. Water formed in the subtropics enters the equatorial region predominantly through the western boundary, while its interior transport is relatively small. The fresher North Pacific ESTMW and Central Mode Water (CMW) are also important sources of the 13°C Water. The ratio of the southern versus the northern origins of the water mass is about 2 to 1 and tends to increase with time elapsed from its origin. Of the total volume of initially tracer-tagged water in the eastern equatorial Pacific, approximately 47.5% originates from depths above σθ = 25.8 kg m−3 and 34.6% from depths below σθ = 26.6 kg m−3, indicative of a dramatic impact of mixing on the route of subtropical water to becoming the 13°C Water. Still only a small portion of the water formed in the subtropics reaches the equatorial region, because most of the water is trapped and recirculates in the subtropical gyre.

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