1
Antarctic Circumpolar Current
NADW AABW
2
Circulation of Deep Waters in Southern Ocean
50ºS ACC 65ºS
Antarctic Circumpolar Current (ACC) flows eastward and extends from surface into the Deep Sea
3
N-S Cross Sections Atlantic Ocean
3
4
Zonal (E-W) Cross Sections (at 7ºS) in Atlantic Ocean
4
5
N-S Cross Sections in the Pacific Ocean
5
6
6
Zonal (E-W) Cross Sections (30ºS) in Pacific Ocean
7
North-South Cross Sections in Indian Ocean
7
8
T and S in Atlantic versus Pacific Oceans
0
1000
2000
3000
4000
5000
6000
0 2 4 6 8 10 12 14 16
Pot Temp (deg C)
Dep
th (m
)
N. Atl (40N)
S Atl (40S)
S. Pac (37S)
N Pac (49N)
0
1000
2000
3000
4000
5000
6000
34.0 34.5 35.0 35.5 36.0
Salinity
Dep
th (
m)
N. Atl (40N)
S Atl (40S)
S. Pac (37S)
N Pac (49N)
0
1
2
3
4
5
6
34.0 34.2 34.4 34.6 34.8 35.0 35.2
Salinity
Po
t T
em
p (
º C
)
N. Atl (40N)
S Atl (40S)
S. Pac (37S)
N Pac (49N)
9
Nitrate Trends in Deep SeaAtlantic Ocean Southern Ocean Pacific Ocean
(umol/kg)
10
Atlantic Ocean Southern Ocean Pacific Ocean
Oxygen Trends in Deep Sea
(umol/kg)
11
CFC History in the Atmosphere
11
12
CFCs in the N. Atlantic Ocean
E-W Cross Section at 10ºN (1993)
N-S Cross Section (1988)
12
13
Theoretical Circulation for Deep Waters
14
CFC Ages of Water Parcels in Deep Atlantic
Yea
rs
(~3000m)
15
CFCs in Pacific Ocean
16
Aging Deep Water using Radiocarbon (14C)
12C = 99% 13C= 1% 14C = 10-10 %
Radioactive Decay Equation
Nt = No * e-λt , where t = time and λ = 0.69/t½
t½ (half-life) = 5700 years for 14C
Nt/No = e-λt or ln (Nt/No) = - λt
Time (t) = -5700 yrs/0.69 * ln(Nt/No)
17
14C Distribution in Deep Sea
(per mil)
1000
2000
3000
4000
5000
6000
0
1000
18
Interbasin Trends in 14C in Deep Sea
19
Ocean’s Uptake of Fossil-fuel
Combustion CO2
Ocean adsorbs about one-third of the CO2 produced by fossil fuel combustion