Joos, Plattner, Stocker, Körtzinger, and Wallace (2003). EOS 84, 197-204.

WP10The motivation

Electrochemical sensor(Seabird SBE 43/IDO)

Optode sensor (Aanderaa 3830)

Measurement range:120% of surface saturation

Initial accuracy:2% of saturation

Response time:6 s (e-folding time)

Measurement range:0-120% of surface saturation(0-500 µM)

Precision:<1 µM (0.4%)

Initial accuracy:8 µM or 5% (whichever is greater)

Response time:25 s (e-folding time)

Principle: Life time based dynamic fluorescence quenching

Principle: Clark-type polarographic membrane sensor

UW floats(S. Riser)

WP10The technological situation

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, Körtzinger 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

WP10The technological situation

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.

quasi-stationary float

WP10The science showcase

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

• February 2009: field study with deployment of 2 floats (77 and 90 profiles, resp.)

• 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

• February 2008: field study with deployment of 4 floats (all still active in Oct. 2009)

WP10The technological development

PROVOR CTS3 DO PROVCARBON

Final proof-of-concept field experiment using 6 newly developed oxygen floats is successfully running since Feb. 2008

All four PROVOR CTS3 DO float still active after 73-83 profiles PROVCARBON float stopped after 77 and 90 profiles, resp. Evaluation of field experiment data ongoing

WP10The field experiment

Oxygen time-series

Example: 90 profiles by float WMO #6900632 showing upwelling dynamics off Mauritania

active coastalupwelling of low-oxygen waters

Sub-surface respiration of organic matter

produced in upwelled waters

WP10The scientific potential of an ARGO O2 observatory

Estimation of the wind speed dependence of the gas transfer coefficient (k660) from three years of data in the Labrador Sea convection region

Kihm and Körtzinger, in prep.

WP10The scientific potential of an ARGO O2 observatory

Estimation of sub-surface oxygen utilization rates from three years of data in the Labrador Sea convection region

Kihm and Körtzinger, in prep.

2003 20042005

WP10The scientific potential of an ARGO O2 observatory

Keeling, Körtzinger, and Gruber (2010). Ocean deoxygenation in a warming World. Annual Review of Marine Science. 2, in press.

WP10The emerging global picture of O2 trends

The latest OMZ trends ...

Model vs. observations: A16N

Simulated and observed decadal variability are of similar order

Internal variability of a specific year is up to 20 μmol/kg

Observed O2-decrease from 1993 and 2003 is 30 μmol/kg

Simulated internal varia-bility is up to 45 μmol/kg

Impact of the Mt. Pinatubo eruption is negligible

Johnson et al. (2007)

IntroductionMethodsResultsCaveats/closing thoughts

The present oceanThe future oceanLong-term changes

Frölicher et al. (2009, GBC)

Large local O2-decrease in thermocline of the North Pacific and the Southern Ocean (due to reduced air-sea gas exchange and reduced ventilation, partly

compensated by biological processes)

O2-decrease in deep North Atlantic (more efficient PO4 utilization due to lower ventilation)

O2-increase in tropical thermocline (large decrea-se in export production, possibly reduction in water mass ages)

Regional maximum O2 decrease/increase

Depth Depth

Frölicher et al. (2009, GBC)

IntroductionMethodsResultsCaveats/closing thoughts

The present oceanThe future oceanLong-term changes

Global decrease in dissolved oxygen

Total O2 content is projected to decrease by 5.9 Pmol (2.6%) by year 2100.

Solubility-driven changes are responsible for at least 50% of the total decrease.

Additional O2 loss resulting from change in ocean circulation and biology

Frölicher et al. (2009, GBC)

solubility-driven

stratficiation

IntroductionMethodsResultsCaveats/closing thoughts

The present oceanThe future oceanLong-term changes

Johnson, K.S., W.M. Berelson, E.S. Boss, Z. Chase, H. Claustre, S.R. Emerson, N. Gruber, A. Körtzinger, M.J. Perry, and S.C. Riser (2009). Observing biogeochemical cycles at global scales with profiling floats and gliders: prospects for a global array, Oceanography, 22, 217-225.

WP10The BGC community is starting to embrace ARGO