SAMOC: South Atlantic Meridional
Overturning Circulation
International Programs and Plans
http://www.aoml.noaa.gov/phod/research/moc/samoc/
The South Atlantic: link to the global MOC
Deep and abyssal circulation
Upper and Intermediate circulation
Stramma, Encyc.Ocean.Sci.,, 2001
Adapted from Donners et al. JPO, 2004
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
Meridional heat flux at 35S
35ºS Meridional Heat Flux (PW)
1.2
Ecco monthly and 1 yr running mean
AX18
0.8
0.4
0
-0.4
1965
1970
XBT estimates from Garzoli & Barringer 2007
1975
1980
1985
1990
1995
2000
2005
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:
Potential Density
• 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
The SA is not a
passive path for
the MOC return
flows
From Garzoli and Matano, 2011
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.
Area of the existing and proposed
SAMOC observational program.
Color contours are time-mean SST from
World Ocean Atlas.
XBT and CTD/LADCP lines
XBT line
AX18 35°S
Dates
Institution
Quarterly AOML/SHN
Status
Funded
AX97 22°S
Quarterly FURG/AOML
Funded
AX25 GoodHope line
Twice/ UCT/AOML
year
BiSIO
monthly
Funded
Dates
2011
Institution
AOML/PMEL
Status
Funded
Nov-11
Nov-11
March
2011
Shirshov
URI/SIO
Shirshov
Funded
Funded
Funded
GoodHope line.
RV Vavilov
Vema Channel and SAM
region. RV Akademik Ioffe
Shirshov/IFREMER
Funds to be renewed
every year
Funds to be renewed
every year
Drake Passage
RRS J.C.Ross
DIMES (west of Drake)
RV James Cook
NOC
Funds to be renewed
every year
Funds to be renewed
every year
AX22 Drake Passage
CTD line
CLIVAR repeat Hydro.
30°S.
Drake Passage
Drake Passage. cDrake
Scotia Sea & Transits Malvinas, S. Georgia, S.
Orkney, and Antarctic
Peninsula SADCP, TSG.
RV Vavilov
NOC/BAS
Funded
Moored time-series observations
Moored Instruments
Western boundary pilot
measurements (3 PIES/1 CPIES)
Eastern boundary pilot
measurements (2 CPIES)
Eastern boundary pilot
measurement augmentation (2
CPIES)
cDrake PIES/CPIES
GoodHope line. Tall moorings
GoodHope line PIES
OOI
Dates
Institution
Started in 2009 NOAA
Started in 2007 IFREMER
ANR
To be deployed
2011
Started 2007 URI/SIO
AWI
AWI
WHOI/SIO
POC
Meinen, Garzoli,
Baringer, Goni
Speich
Speich
Chereskin/Donhue
Boebel
Boebel
Send
AX18
SAMOC-W
Schematic of the existing pilot measurement systems
as of November 2010 (eastern boundary moorings will
be redeployed in 2011) at 34.5°S
SAMOC-E
URI C-Pressure Inverted EchoSounders
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
Western boundary water masses
Continental shelf
0
Pressure (dbars)
50
100
150
TW
AAIW
200
0
20
40
60
80
100
120
140
160
180
Distance (km)
UCDW
NADW
LCDW
 (°C)
AABW
S
O2 (ml/l)
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.
SAM July 2011
Proposed array
The proposed array along 35°S 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 34.5°S.
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
Proposed array details
Moored Instruments
Agency
(1) Dynamic height moorings (8)
NSF
(2) Deployment cruise and trans-basin
hydrographic cruise
Western boundary PIES (5)/CPIES (1), NOAA
interior PIES-DP (4)
(1) Eastern boundary CPIES(6), ADCP ANR
(1) and bottom pressure recorder (1)
(2) Goodhope PIES (7)
(3) Biogeochemical sampling during
trans-basin hydrographic cruise
Western boundary ADCP (1) and
Ministry of
bottom pressure recorder (1)
Science and
Technology
Shallow morrings @~35°S
FURG
Ship time for western boundary turn- FAPESP
around and recovery cruise
Instrumentation to augment western
Argentina
boundary moorings and hydrography
Ship time for eastern boundary turnSANAP
around and recovery cruise
PIs
Country Status
S. Dong, R.
USA
Proposed
Perez, J. Sprintall,
R. Fine, G. Flierl,
S. Baker-Yeboah
R. Perez, S.
USA
Proposed
Dong, C. Meinen,
S. Garzoli, G.
Goni, M. Baringer
S. Speich
France Proposed
E. Campos
Brazil
Proposed
L. Niencheski
E. Campos
Brazil
Brazil
Proposed
Proposed
A. Piola
Argentina To be
proposed
South
To be
Africa
proposed
I. Ansorge, C.
Reason
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