The shallow meridional overturning circulation in the northern Indian Ocean and its interannual variability

2005 ◽  
Vol 22 (2) ◽  
pp. 220-229 ◽  
Author(s):  
Hu Ruijin ◽  
Liu Qinyu ◽  
Wang Qi ◽  
J. Stuart Godfrey ◽  
Meng Xiangfeng
Keyword(s):  
Indian Ocean ◽  
Interannual Variability ◽  
Meridional Overturning Circulation ◽  
Northern Indian Ocean ◽  
Overturning Circulation ◽  
Meridional Overturning

scholarly journals The Interannual Variability of Shallow Meridional Overturning Circulation and its association with the South-West Indian Ocean Heat Content variability

2021 ◽  
Author(s):  
Rahul U Pai ◽  
Anant Parekh ◽  
Jasti S. Chowdary ◽  
C. Gnanaseelan
Keyword(s):  
Indian Ocean ◽  
Interannual Variability ◽  
Sea Level ◽  
Southern Oscillation ◽  
Heat Content ◽  
Meridional Overturning Circulation ◽  
Ocean Heat Content ◽  
The South ◽  
Overturning Circulation ◽  
Meridional Overturning

Abstract The present study examines interannual variability of Shallow Meridional Overturning Circulation (SMOC) using century long reanalysis data. The strength of the transport associated with SMOC is calculated by meridional overturning streamfunction. The interannual variability in SMOC is found maximum between the 5oS and 15oS and displaying strong signals after 1940s. A year for which the meridional overturning streamfunction detrended anomaly is greater (lesser) its standard deviation is identified as strong (weak) SMOC year. For strong (weak) SMOC year composite displayed more (less) southward transport (~2.5 Sv) and shown excess (less) subduction over the South Indian Ocean. During strong (weak) years, the excess (less) southward heat transport (~0.25PW) leads to reduction (increase) in the upper 200m Ocean Heat Content (OHC) and sea level over the Southwest Indian Ocean (SWIO). The results obtained are well supported by tide gauge and satellite measured sea level data for the available period. Further analysis reveals that the SMOC variability is primarily driven by change in zonal wind stress south of the equator and displayed association with the Southern Oscillation Index. The Ocean model-based sensitivity experiments confirms that the OHC variability over SWIO is closely associated with the SMOC variability and is primarily driven by local wind forcing as a response to El Niño Southern Oscillation. However, the role of remote forcing from Pacific through Oceanic pathway over SWIO is absent. Study attempts to provide a comprehensive view on the interannual variability of SMOC and its linkage to OHC variability over SWIO during last century.

scholarly journals Atmosphere drives recent interannual variability of the Atlantic meridional overturning circulation at 26.5°N

2013 ◽  
Vol 40 (19) ◽  
pp. 5164-5170 ◽  
Author(s):  
C. D. Roberts ◽  
J. Waters ◽  
K. A. Peterson ◽  
M. D. Palmer ◽  
G. D. McCarthy ◽  
...  
Keyword(s):  
Interannual Variability ◽  
Atlantic Meridional Overturning Circulation ◽  
Meridional Overturning Circulation ◽  
Overturning Circulation ◽  
Meridional Overturning

Impact of the Equatorial Wind Stress on the Indian Ocean Shallow Meridional Overturning Circulation During the IOD Mature Phase

2020 ◽  
Author(s):  
Linfang Zhang ◽  
Yaokun Li ◽  
Jianping Li
Keyword(s):  
Indian Ocean ◽  
Wind Stress ◽  
Meridional Overturning Circulation ◽  
Ekman Transport ◽  
Overturning Circulation ◽  
Mature Phase ◽  
Meridional Overturning ◽  
The Indian Ocean ◽  
Upper Level ◽  
The Impact

<p>            This paper investigates the impact of the equatorial wind stress on the Indian Ocean Shallow Meridional Overturning Circulation (SMOC) during the India Ocean Dipole (IOD) mature phase. The results show that the equatorial zonal wind stress directly drives the meridional motion of seawater at the upper level. In normal years, the wind stress in the Indian Ocean is easterly between 30°S-0°and the westerly wind is between 0°and 30°N, which contributes to a southward Ekman transport at the upper level to form the climatological SMOC. During the years of positive IOD events, abnormal easterly wind near the equator, accompanying with the cold sea surface temperature anomaly (SSTA) along the coast of Sumatra and Java and the warm SSTA along the coast of East Africa, brings southward Ekman transport south of the equator while northward Ekman transport north of the equator. This leads the seawaters moving away from the equator and hence upwelling near the equator as a consequence, to form a pair of small circulation cell symmetric about the equator.</p>

scholarly journals Recent Wind-Driven Variability in Atlantic Water Mass Distribution and Meridional Overturning Circulation

2017 ◽  
Vol 47 (3) ◽  
pp. 633-647 ◽  
Author(s):  
Dafydd Gwyn Evans ◽  
John Toole ◽  
Gael Forget ◽  
Jan D. Zika ◽  
Alberto C. Naveira Garabato ◽  
...  
Keyword(s):  
Interannual Variability ◽  
Mass Distribution ◽  
Water Mass ◽  
Heat Content ◽  
Atlantic Meridional Overturning Circulation ◽  
Meridional Overturning Circulation ◽  
Subtropical Gyre ◽  
Thermocline Depth ◽  
Overturning Circulation ◽  
Meridional Overturning

AbstractInterannual variability in the volumetric water mass distribution within the North Atlantic Subtropical Gyre is described in relation to variability in the Atlantic meridional overturning circulation. The relative roles of diabatic and adiabatic processes in the volume and heat budgets of the subtropical gyre are investigated by projecting data into temperature coordinates as volumes of water using an Argo-based climatology and an ocean state estimate (ECCO version 4). This highlights that variations in the subtropical gyre volume budget are predominantly set by transport divergence in the gyre. A strong correlation between the volume anomaly due to transport divergence and the variability of both thermocline depth and Ekman pumping over the gyre suggests that wind-driven heave drives transport anomalies at the gyre boundaries. This wind-driven heaving contributes significantly to variations in the heat content of the gyre, as do anomalies in the air–sea fluxes. The analysis presented suggests that wind forcing plays an important role in driving interannual variability in the Atlantic meridional overturning circulation and that this variability can be unraveled from spatially distributed hydrographic observations using the framework presented here.

scholarly journals Interannual Variability of the Global Meridional Overturning Circulation Dominated by Pacific Variability

2020 ◽  
Vol 50 (3) ◽  
pp. 559-574
Author(s):  
Neil F. Tandon ◽  
Oleg A. Saenko ◽  
Mark A. Cane ◽  
Paul J. Kushner
Keyword(s):  
Interannual Variability ◽  
Large Scale ◽  
Southern Oscillation ◽  
Meridional Overturning Circulation ◽  
Ekman Transport ◽  
Prominent Feature ◽  
Overturning Circulation ◽  
Near Surface ◽  
The Pacific ◽  
Meridional Overturning

AbstractThe most prominent feature of the time-mean global meridional overturning circulation (MOC) is the Atlantic MOC (AMOC). However, interannual variability of the global MOC is shown here to be dominated by Pacific MOC (PMOC) variability over the full depth of the ocean at most latitudes. This dominance of interannual PMOC variability is robust across modern climate models and an observational state estimate. PMOC interannual variability has large-scale organization, its most prominent feature being a cross-equatorial cell spanning the tropics. Idealized experiments show that this variability is almost entirely wind driven. Interannual anomalies of zonal mean zonal wind stress produce zonally integrated Ekman transport anomalies that are larger in the Pacific Ocean than in the Atlantic Ocean, simply because the Pacific is wider than the Atlantic at most latitudes. This contrast in Ekman transport variability implies greater variability in the near-surface branch of the PMOC when compared with the near-surface branch of the AMOC. These near-surface variations in turn drive compensating flow anomalies below the Ekman layer. Because the baroclinic adjustment time is longer than a year at most latitudes, these compensating flow anomalies have baroclinic structure spanning the full depth of the ocean. Additional analysis reveals that interannual PMOC variations are the dominant contribution to interannual variations of the global meridional heat transport. There is also evidence of interaction between interannual PMOC variability and El Niño–Southern Oscillation.

scholarly journals Observed interannual variability of the Atlantic meridional overturning circulation at 26.5°N

2012 ◽  
Vol 39 (19) ◽  
pp. n/a-n/a ◽  
Author(s):  
G. McCarthy ◽  
E. Frajka-Williams ◽  
W. E. Johns ◽  
M. O. Baringer ◽  
C. S. Meinen ◽  
...  
Keyword(s):  
Interannual Variability ◽  
Atlantic Meridional Overturning Circulation ◽  
Meridional Overturning Circulation ◽  
Overturning Circulation ◽  
Meridional Overturning
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