SAMOC: South Atlantic Meridional Overturning Circulation

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SAMOC South Atlantic Meridional Overturning
Circulation

• International Programs and Plans
• http//www.aoml.noaa.gov/phod/research/moc/samoc/

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The South Atlantic link to the global MOC
Deep and abyssal circulation
Upper and Intermediate circulation
The South Atlantic is the gateway for NADW to the
rest of the world ocean and to the return of
thermocline and AAIW waters to the North Atlantic
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Meridional heat flux at 35S
XBT estimates from Garzoli Barringer 2007
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Water mass conversions in the South Atlantic

• Are concentrated in regions of intense mesoscale
  variability such as the southwestern Atlantic or
  the Cape Basin. The signs and magnitude of the
  conversions indicated by POCM are in agreement
  with those suggested by observations
• Surface and deep waters to intermediate waters
  in the SWA
• Intermediate to surface waters in the Cape Basin
• Intermediate to surface waters in the tropics

Potential Density
The SA is not a passive path for the MOC return
flows
From Garzoli and Matano, 2011
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S A Meridional Overturning Circulation (SAMOC)
SAMOC aims to resolve the mean and varying
components of the MOC, as well as the associated
heat and salt fluxes. SAMOC will observe and
model the changes in the relative contributions
of different water masses to the upper ocean
return flow of the MOC in the South Atlantic.
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XBT and CTD/LADCP lines
XBT line Dates Institution Status
AX18 35S Quarterly AOML/SHN Funded
AX97 22S Quarterly FURG/AOML Funded
AX25 GoodHope line Twice/ year UCT/AOML Funded
AX22 Drake Passage Bi-monthly SIO Funded

CTD line Dates Institution Status
CLIVAR repeat Hydro. 30S. 2011 AOML/PMEL Funded
Drake Passage Nov-11 Shirshov Funded
Drake Passage. cDrake Nov-11 URI/SIO Funded
Scotia Sea Transits - Malvinas, S. Georgia, S. Orkney, and Antarctic Peninsula SADCP, TSG. RV Vavilov March 2011 Shirshov Funded
GoodHope line. RV Vavilov   Shirshov/IFREMER Funds to be renewed every year
Vema Channel and SAM region. RV Akademik Ioffe     Funds to be renewed every year
Drake Passage RRS J.C.Ross   NOC Funds to be renewed every year
DIMES (west of Drake) RV James Cook   NOC/BAS Funds to be renewed every year
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Moored time-series observations
Moored Instruments Dates Institution POC
Western boundary pilot measurements (3 PIES/1 CPIES) Started in 2009 NOAA Meinen, Garzoli, Baringer, Goni
Eastern boundary pilot measurements (2 CPIES) Started in 2007 IFREMER Speich
Eastern boundary pilot measurement augmentation (2 CPIES) To be deployed 2011 ANR Speich
cDrake PIES/CPIES Started 2007 URI/SIO Chereskin/Donhue
GoodHope line. Tall moorings   AWI Boebel
GoodHope line PIES   AWI Boebel
OOI   WHOI/SIO Send
Schematic of the existing pilot measurement
systems as of November 2010 (eastern boundary
moorings will be redeployed in 2011) at 34.5S
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URI C-Pressure Inverted EchoSounders
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(No Transcript)
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cDrake Dynamics and Transport of the ACC in
Drake Passage

• Determine the time-varying ACC transport
• Describe the mesoscale eddy field
• Guide future monitoring
• Assess model skill

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Western boundary water masses
Continental shelf
? (C)
S
O2 (ml/l)
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South Atlantic MOC (SAM)
Deployed in March 2009 3 PIES 1
CPIES Recovery/turn-around early 2013
Preliminary estimate of the meridional absolute
velocity determined via geostrophy between sites
during the first year of deployment.
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SAM July 2011
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Proposed array
The proposed array along 35S consists of bottom
pressure gauges (cyan squares), upward-looking
ADCPs, mid-depth and deep moorings with full
water-column T, S, p and discrete current
measurements, PIES (black circles), PIES-with
datapods (green circles), and CPIES (black
squares). Color contours are of 27-year mean OFES
meridional velocity along 34.5S.
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Brazilian array
Brazilian proposal to study shelf-deep ocean
interactions The array off Rio Grande will serve
as the shelf boundary of the proposed SAMOC array
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Proposed array details
Moored Instruments Agency PIs Country Status
(1) Dynamic height moorings (8) NSF S. Dong, R. Perez, J. Sprintall, R. Fine, G. Flierl, S. Baker-Yeboah USA Proposed
(2) Deployment cruise and trans-basin hydrographic cruise NSF S. Dong, R. Perez, J. Sprintall, R. Fine, G. Flierl, S. Baker-Yeboah USA Proposed
Western boundary PIES (5)/CPIES (1), interior PIES-DP (4) NOAA R. Perez, S. Dong, C. Meinen, S. Garzoli, G. Goni, M. Baringer USA Proposed
(1) Eastern boundary CPIES(6), ADCP (1) and bottom pressure recorder (1) ANR S. Speich France Proposed
(2) Goodhope PIES (7) ANR S. Speich France Proposed
(3) Biogeochemical sampling during trans-basin hydrographic cruise ANR S. Speich France Proposed
Western boundary ADCP (1) and bottom pressure recorder (1) Ministry of Science and Technology E. Campos Brazil Proposed
Shallow morrings _at_35S FURG L. Niencheski Brazil Proposed
Ship time for western boundary turn-around and recovery cruise FAPESP E. Campos Brazil Proposed
Instrumentation to augment western boundary moorings and hydrography Argentina A. Piola Argentina To be proposed
Ship time for eastern boundary turn-around and recovery cruise SANAP I. Ansorge, C. Reason South Africa To be proposed
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GOODHOPE within SAMOC

• Plans for the future (i.e., within SAMOC)
• To continue the repeat GoodHope line (South
  Africa, Russia, France, Germany)
• To analyse the moorings data from the Pilot
  Project (2011)
• To implement the line with bottom mooring (CPIES,
  ADCPs) starting late 2011, increasing in mooring
  density by 2012
• To develop in collaboration with NOAA-AOML data
  pods for bottom moorings (ADCP and CPIES) and
  initiate an operational frequency of recovery of
  the data

Swart et al. 2008