arne körtzinger ifm-geomar leibniz institute of marine sciences marine biogeochemistry kiel,...
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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
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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
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800
1000
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1400
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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
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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
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