Arne Körtzinger

IFM-GEOMARLeibniz Institute of Marine SciencesMarine BiogeochemistryKiel, Germany

Oceanic oxygen — the oceanographer’s canary bird of climate change

WP 10

Joos et al., 2003

Joos, F., G.-K. Plattner, T.F. Stocker, A. Körtzinger, and D.W.R. Wallace (2003). EOS 84(21), 197-204.

Time series of AOU on isopycnals 26.7, 26.8, 26.9, 27.0, and 27.2 (bottom to top) in the western subarctic Pacific (1968-1998).

Annual averaged increase rate of AOU (µmol kg-1 yr-1) during the period 1985 to 1999 along 165°E (left) and 47°N (right) lines in the North Pacific.

AOU increase: ~0.9 ± 0.5 µmol kg-1 yr-1

AOU increase: up to +5 µmol kg-1 yr-1

Oxygen Trends: What the observations tell...

Ono et al., GRL 28, 2001.Watanabe et al., GRL 28, 2001.

Kim et al., MTS Journal, 33, 2001.

~25 µmol L-1

Oxygen Trends: What the observations tell...

Courtesy of Nicolas Gruber

Oxygen Trends: What the models tell...

Oxygen – the oceanographer’s canary bird of climate change

Oxygen Trends: What the models tell...

Zonally averaged O2 changes 2000-2100 in the Atlantic Ocean from a transient simulation with the NCAR coupled biogeochemical-climate model (SRES A2 scenario).

Joos et al., University of Bern, Physics Institute, Climate and Environmental Physics

“Mirror Image Approach“ – a flawless method to track anthropogenic CO2?

Separation of terrestrial and oceanic sinks for anthropogenic CO2

Oceanic oxygen can improve atmospheric O2/N2 constraint

on ocean/land partitioning of anthropogenic CO2

Complications:• O2 outgassing• Local APO signals

O2 and CO2 fluxes in upwelling regions – imprint on APO

CO2 flux [mmol m-2 d-1]

O2 f

lux

[m

mo

l m-2 d

-1]

O2 and CO2 fluxes in upwelling regions – imprint on APO

(y = -0.97 • x + 29.6)

slope for pure gas exchange

slope for Redfieldian net production

observed slope

O2 and CO2 fluxes in upwelling regions – imprint on APO

The Kiel oxygen float project (since 2002)

The luminophore (organic Pt complex) is immobilized in a sensing foil which is excited with blue light (505 nm) and produces a red luminescence. The intensity and lifetime of the emission depend on the oxygen concentration in the foil and hence the ambient seawater. The dynamic quenching effect can be used to measure oxygen.

1

1O 0

2

svK = Luminescence lifetime without O2

= Luminescence lifetime with O2

The oxygen optode – a major step forward

432

434

436

438

440

442

444

446

448

450

452

454

250270290310330350370390410430450470490510530550

Julian day

Oxygen in

ventory (0-1400 m

) [m

ol O

2 m-

2 ]

0

200

400

600

800

1000

1200

1400

1600

M

ixe

d la

ye

r d

ep

th

(m

)

Oxygen inventory

Mixed layer depth

2003 2004

250 270 290 310 330 350 5 25 45 65 85 105 125 145 165 185

Oxyg

en

in

ve

nto

ry 0

-1

40

0 m

(m

ol O

2 m-

2 )

0

200

400

600

800

1000

1200

1400

1600

1800

2000

290 295 300 305 310 315 320 325

Oxygen (mmol m-3)

Pressure (dbar)

Oct. 5, 2003 (profile 4)Oct. 26, 2003 (profile 7)Nov. 2, 2003 (profile 8)Dec. 7, 2003 (profile 13)Dec. 28, 2003 (profile 16)Feb. 8, 2004 (profile 22)Feb. 22, 2004 (profile 24)Mar. 21, 2004 (profile 28)Apr. 4, 2004 (profile 30)Apr. 11, 2004 (profile 31)

A

C

B

Körtzinger et al. (2004). The ocean takes a deep breath. Science 306, 1337.

The Labrador Sea showcase: The ocean‘s breathing

quasi-stationary float

The Labrador Sea showcase: The ocean‘s breathing

quasi-stationary float

Peakconvection

O2 inventory builds up with progressing convection

Deep O2 inventory sealed off by low-salinity cap

Decay of O2 inventory through lateral export and respiration

0

200

400

600

800

1000

1200

1400

1600

1800

2000

55 60 65 70 75 80 85 90 95 100 105

Oxygen saturation [%]

Pre

ssur

e [d

bar]

Profile 1

Profile 2

Profile 3

Profile 4

Profile 5

Profile 6

Profile 7

Profile 8

Profile 9

Profile 10

Float 7900076

0

200

400

600

800

1000

1200

1400

1600

1800

2000

-2 -1.5 -1 -0.5 0 0.5 1

Temperature [°C]

Pre

ssur

e [d

bar]

Profile 1

Profile 2

Profile 3

Profile 4

Profile 5

Profile 6

Profile 7

Profile 8

Profile 9

Profile 10

Float 7900076

An example from our Weddell Sea oxygen float study68°S, 0°W

APEX float with ice detection alogorithm, O2 option (optode), and RAFOS option

Progressive cooling freezing

O2 disequilibrium

An example from our Weddell Sea oxygen float study62°S, 40°W

0

200

400

600

800

1000

1200

1400

1600

1800

2000

55 60 65 70 75 80 85 90 95 100 105 110

Oxygen saturation [%]

Pre

ssur

e [d

bar]

Profile 26

Profile 27

Profile 29

Profile 31

Profile 32

Profile 33

Profile 35

Profile 36

Float 7900095

Float touching down onSouth Orkney Islands Slope

Increasing O2 saturation

0

200

400

600

800

1000

1200

1400

1600

1800

2000

-2 -1.5 -1 -0.5 0 0.5 1

Temperature [°C]

Pre

ssur

e [d

bar]

Profile 26

Profile 27

Profile 29

Profile 31

Profile 32

Profile 33

Profile 35

Profile 36

Float 7900095

Progressive warming

APEX float with ice detection alogorithm, O2 option (optode), and RAFOS option

Why is there little anthropogenic CO2 in the Antarctic Bottom Water?Poisson, A; Chen, C.-T. A.

Deep-Sea Research, 34, 1255-1275. 1987.

0

200

400

600

800

1000

1200

1400

1600

1800

2000

270 275 280 285 290 295

Oxygen [µM]

Pre

ssu

re [d

ba

r] Float #1, 1st profile

Float #2, 1st profile

0

200

400

600

800

1000

1200

1400

1600

1800

2000

285 290 295 300 305 310 315

Pre

ssur

e [d

bar]

Float #1, profiles 1-3

Float #2, profiles 1-3

Winkler titrations

Both sensors in good agreementO2 = 1.6 µmol/L

(p > 800 dbar)

Körtzinger et al. (2005). J. Atm. Ocean. Techn. 22, 302-308.

Accuracy:Both sensors off by17.5 ± 2.5 µmol/L

0

200

400

600

800

1000

1200

1400

1600

1800

2000

270 275 280 285 290 295

Oxygen [µM]

Sensor-to-sensor agreement / Accuracy of sensor batch (optode)

Körtzinger et al. (2005). High-quality oxygen measurements from profiling floats: A promising new technique.J. Atm. Ocean. Techn. 22, 302-308.

340

350

360

370

380

390

400

410

420

430

440

1 21 41 61 81 101 121 141 161 181

Number of datapoint

Oxy

gen

[µM

]

2

3

4

5

6

7

8

9

10

Tem

pera

ture

[°C

]

Oxygen, measuredOxygen, calculatedTemperature

Sensor in air

292.5

293.0

293.5

294.0

294.5

295.0

295.5

296.0

296.5

0 100 200 300 400 500 600

Day

Oxy

gen

conc

entr

atio

n (µ

mol

L-1

)

35.99

36.00

36.01

36.02

36.03

36.04

36.05

36.06

36.07

36.08

S,T

,p (

kg m

-3)

OxygenIn-situ density

p = 1799.2 ± 0.2 dbar

Tengberg et al. (2006). Evaluation of a life time based optode to measure oxygen in aquatic systems. Limnol. Oceanogr. Methods 4, 7-17.

Drift check possible through air measurements

High long-term stability

O2 = 295.0 ± 0.7 µmol/L

Drift check / Long-term stability

CarboOcean WP10

PROVOR-DO PROVOR-CarboOcean

Oxygen sensor Oxygen sensor

PIC sensor

• March 2007: Delivery of prototype 2 floats from MARTEC company

• Spring 2007: Testing of floats (vibration, tank, basin) at IFREMER

• Spring/summer 2007: Sea trials of floats

• November 2006: Delivery of 2 prototype floats from MARTEC company

• Nov./Dec. 2006: Testing of floats (vibration, tank, basin) at IFREMER

• February 2007: Deployment during R/V Poseidon Cruise 348 by IFM-GEOMAR north of the Cape Verde archipelago

Active floats with DO sensor: 65(measuring profiles from 25 Aug. to Sep. 24)

Oxygen floats that are out there …

WHY adding oxygen to ARGO?Objective:

To determine seasonal to decadal-time changes in sub-surface

oceanic oxygen storage and transport

In order to

• Detect changes in ocean biogeochemistry (Miner's canary bird of

climate change)

• Improve atmospheric O2/N2 constraint on ocean/land partitioning

of anthropogenic CO2

• Determine seasonal to interannual net remineralization rates as a

proxy for export production

• Help interpretation of variations in water mass ventilation rates

• Provide data (initial conditions, evaluation) for ocean bgc models

• Help interpretation of sparse data from repeat hydrographic

surveys