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