The Atlantic Ocean: from Meteor through WOCE

1
The Atlantic Ocean from Meteor through WOCE

• R Allyn Clarke
• Bedford Institute of Oceanography

2
Challenger Expedition 1873-1875
3
Meteor Expedition 1925-1927
1926
1927
1925
4

• Meridional Sections
• Georg Wüst (1935)
• Meteor plus other data
• other data spans decades

5
Western Section
1000 m
2000 m
3000 m
4000 m
Salinity
5000 m
Oxygen
Equator
Labrador Sea
Antarctica
6
Central Section
1000 m
2000 m
3000 m
4000 m
Temperature
5000 m
Sigma T
Equator
Irminger Sea
Antarctica
7
Eastern Section
1000 m
2000 m
3000 m
4000 m
Salinity
5000 m
Oxygen
Equator
Rockall Trough
Antarctica
8
Wüst (1935)
30

• Subantarctic Intermediate Water
• SAAIW
• defined by the intermediate salinity minimum
• also seen in temperature and oxygen
• figure shows subantarctic component

50
70
SAAIW
9
Wüst (1935)

• Upper North Atlantic Deep Water
• uNADW
• intermediate salinity Maximum
• also in temperature
• Mediterranean

SAAIW
30
20
15
uNADW
10
Wüst (1935)

• Middle North Atlantic Deep Water
• mNADW
• intermediate oxygen maximum
• salinity maximum
• North Atlantic component

SAAIW
90
60
40
mNADW
uNADW
11
Wüst (1935)
Antarctic Bottom Water AABW
SAAIW
30
AABW
10
90
uNADW
mNADW
12
International Geophysical Year
1958
1957
12 zonal IGY trans Atlantic sections winter and
summer surveys of the northern sub polar gyre
ICES Polar Front Survey
13
The 70s and the 80s
Fukumori, Martel Wunsch, 1991
GEOSECS Atlantic 1972-73
TTO, Long Lines SAVE
14
We believed we knew a lot about the North
Atlantic when planning WOCE
15
WOCE planning for the Atlantic
One time hydrography
Repeat hydrography
Moorings
16
How did we do?
Moorings
One time Hydrography
17
Surface Drifters Annual Trajectories 1990 to
1999 (Fratantoni, JGR 106 (C10), 2001)
18
Surface Drifters No of Observations per degree
square (Fratantoni, JGR 106 (C10), 2001)
19
Fastest and Slowest surface currents (Fratantoni,
JGR 106 (C10), 2001)
Surface Drifters
20
Surface Drifters Eddy Kinetic Energy (Fratantoni,
JGR 106 (C10), 2001)
21
Surface Drifters Sub Tropical Sub Polar
Exchange (Cuny, Rhines, Niiler Bacon, JPO
32(2), 2002)
22
Western Atlantic WOCE Section Salinity
23
Western Atlantic WOCE Section Silicate
24
Atlantic WOCE A16 Section Salinity Oxygen
25
New Climatology North Atlantic Mean Properties on
?? 26.50 Lozier, Owens Curry Prog. Ocean.
36(1), 1995
Pressure
Theta
Salinity
Oxygen
Std Dev ?
26
Properties on the AAIW (Oxygen Maximum) Talley,
1996
Salinity
Oxygen
27
CFCs in the Atlantic Overturning
Circulation Rhein, Fischer, Smethie,
Smythe-Wright, Weiss, Mertens, Min, Fleischmann
Putzka, JPO, 2002 Andrie, Rhein, Freudfenthal
Plahn, DSR I, 49(2), 2002 Andrie, The South
Atlantic, 1996
CFC-11 inventory in the subpolar gyre
Increase over the 90s of
1983 1993
CFC-11 in DWBC at the Equator
28
Intermediate Circulation Labrador Irminger
Seas Lavender, Davis, Owens, Nature
407(6800), 2000
V lt .05 m/s displacements over 30 days V gt .05
m/s displacements over 8 days
750 m streamfunction

• Mixed Layer Depth
• lt 400 m 400 lt ? lt 800 ? gt 800 m

29
Intermediate Circulation subpolar North
Atlantic Bower, Le Cann, Rossby, Zenk, Gould,
Speer, Richardson, Prater Zhang, Nature
419(6907), 2002
Upper level ?? 27.5
?? 27.5 LSW layer
LSW layer
30
Intermediate Circulation Equatorial
Atlantic Molinari, Garzolli Schmidt, GRL 26(3),
1999 Stramma Schott, DSR II 46, 2000
31
Float Trajectories Black - RAFOS Gray - ALACE
Intermediate Circulation Subtropical South
Atlantic (750 m.) Schmid, Siedler Zenk, JMR
30(12), 2000
Potential Vorticity
AAIW Circulation
32
Western Boundary Transports at 42 N Hendry,
Clarke Yashayaev
33
Western Boundary Transports at 26.5 N Fillenbaum,
Lee, Johns Zantopp, JPO 27(1), 1997
Volume Transport
Heat Transport
34
Deep Western Boundary Current in the Equatorial
Atlantic Fischer Schott, JGR
102(C13), 1997
35
Deep Western Boundary Current at 18ºS 18 month
record mean currents Weatherly, Kim Kontar JPO
30(5) 2000
uNADW
AAIW
LNADW
AABW
36
AABW Transport at 30ºS Hogg, Seidler Zenk,
JPO 29(2), 1999 Zenk, Seidler, Lenz Hogg
JPO 29(11), 1999
Hunter Channel
37
Brazil Malvinas Current Confluence at
38ºS Maamaatuaiahutapu, Garçon, Provost
Mercier, JMR 56(2), 1998
41
29
Rel. 3000 m
12.6
Rel. 1500 m
3.4
3
3.4
1.2
3
30
56
23
19.8
6.8
3.8
2.2
1.4
30
1.8
20
44
1.7
46
37
35
6
7.6
1.5
2.1
1.4
0.4
38
Volume Transport of the Malvinas Current at
41ºS Vivier Provost, JGR 104(C9), 1999
Mean Velocity
T/P Moorings CTDs
Transports
? T/P - mooring
39
Circulation of the South Atlantic Stramma
England, JGR 104, 1999
100 m.
AAIW
SACW
NADW solid AABW dash
40
Changes in the Water Masses of the North
Atlantic Yashayaev, Clarke Lazier
Salinity above Theta to the left dashed contours
are potential density
41
Changes in the Labrador Sea Water Yashayaev
42
Changes in the Water Masses of the North
Atlantic Yashayaev
43
Changes in the Water Masses of the
Atlantic Joyce Zenk Hogg, 1996
0.2
0.0
-0.2
1920 1960 1990
Temperature Anomaly 500 to 2500 dbars Bermuda
Station S
44

• WOCE has provided
• new data and data tools
• New models
• New insights
• New instruments

45
Future Atlantic Work

• Need strategy to improve estimates of air-sea
  fluxes particularly fresh water
• Integration with the Nordic Seas and Arctic
• Continuation of repeat sections associated with
  MOC (augment in the South Atlantic)
• Resurvey for tracers on 5-10 year time scale
• Integration with carbon and biological
  observations and modelling.

46
(No Transcript)