32 years of sea ice physics and biogeochemistry
DESCRIPTION
32 Years of Sea Ice Physics and Biogeochemistry. S.F. Ackley. Sea Ice Scales. Antarctic Sea Ice Profile. Antarctic Sea Ice Freeboards. Conclusions through Halftime ~1994. Algal incorporation in Frazil Ice exceeded incorporation in Columnar Ice - PowerPoint PPT PresentationTRANSCRIPT
32 Years of Sea Ice Physics and Biogeochemistry
S.F. Ackley
Sea Ice Scales
Antarctic Sea Ice Profile
Antarctic Sea Ice Freeboards
Conclusions through Halftime ~1994
• Algal incorporation in Frazil Ice exceeded incorporation in Columnar Ice
• Nearly all Antarctic sea ice contains measurable Chl content but low concentrations
• Primary mechanism of incorporation is wave pumping in frazil-pancake ice
• Concentrations in ice exceeded that in underlying water column by 10x to 100x
Conclusions through Halftime (~1994)
• Algal growth led to nutrient drawdown, so high algal concentrations required renewal of nutrients from surface sea water
• Top surface freezing in autumn led to convective overturning and fueled a fall bloom of algae (Fritsen et al 1994 from ISW)
• Warming leads to porous sea ice, while cooling can cause brine rejection and upwelling (Golden et al 1997)
Krill under Sea Ice
Credit: Klaus Meiners
Krill swarms
First evidence of extensive krill swarms under ice
Krill under sea ice
2nd Half (2007 to Present)
• SIPEX-E.Antarctic Ice—A Seasonal Progression
• SIMBA-Bellingshausen Sea Ice—Temperature Cycling
• DMS and DMSP Production
• A Sea Ice CO2 Pump
ICESat 0166
ICESat 0055
ICESat 1305
ICESat 1297
ICESat 1290
ICESat 0025
Background: AMSR-E ice conc. 10 Oct. 2007; courtesy of G. Spreen
SIPEX Ice temperature and salinity (iron site)
Photo: Mats Granskog
SIPEX Fe biogeochem stations
ice temperature (°C)
-16 -14 -12 -10 -8 -6 -4 -2 0
mea
n i
ce d
epth
(cm
)
-20
0
20
40
60
80
100
120
station 1 station 3station 5station 6station 8station 10station 11station 13station 14
SIPEX Fe biogeochem stations
ice salinity
0 5 10 15 20m
ea
n i
ce
de
pth
(c
m)
-20
0
20
40
60
80
100
120
station 1 station 5station 6station 8station 10station 11station 13station 14
Figure: Delphine Lannuzel
SIPEX - Ice algal biomass
Time →
Chl
orop
hyll a
(mg
m-2)
Rel
ativ
e ic
e co
re d
epth
(%
)
Most of the algal biomass was at the bottom of the cores,except towards the end of the experiment
Time Series Sampling, How does the sea ice at one site change with time? Occupied one floe for 27 days.
Mixture of Ice Types at Ice Station Belgica
Brussels Site - level first year ice- no flooding
Deformed thick ice with snow cover- Fabra Site (60 to 80% neg. freeboard)
open water lead
Liege Site(off photo)
Icebergs
Brussels site- level ice, thin snow Liege site- mod. roughness, thicker snow
Fabra sitehighly deformed, thick snow cover
Brussels site-smooth, thin snow
C. Fritsen C. Fritsen
M. Lewis
SIMBA Brussels SiteTextureG = granularC = columnarFS = froz. snowf = finem = mediumc = coarses = smalll = large
M. Lewis
SIMBA Liège SiteTextureG = granularC = columnarFS = froz. snowf = finem = mediumc = coarses = smalll = large
Brussels Site IMB
Thinner snow cover allows cold pulseto penetrate sea ice
No flooding at snow/ice interface
Radiometer Buoy (Brussels 1)
Ice thickness loss
Ice Temperature (°C)
-7 -6 -5 -4 -3 -2 -1 0
De
pth
(c
m)
-80
-60
-40
-20
0
Brussels 1
Ice Salinity (-)
0 2 4 6 8 10 12 14
De
pth
(c
m)
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-60
-40
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0
Brussels 1
Brine Salinity (-)
0 20 40 60 80 100 120
De
pth
(c
m)
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0
Brussels 1
Ice Temperature (°C)
-7 -6 -5 -4 -3 -2 -1 0
De
pth
(c
m)
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0
Brussels 1Brussels 2
Ice Temperature (°C)
-7 -6 -5 -4 -3 -2 -1 0
De
pth
(c
m)
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-60
-40
-20
0
Brussels 1Brussels 2Brussels 3
Ice Temperature (°C)
-7 -6 -5 -4 -3 -2 -1 0
De
pth
(c
m)
-80
-60
-40
-20
0
Brussels 1Brussels 2Brussels 3Brussels 4
Ice Temperature (°C)
-7 -6 -5 -4 -3 -2 -1 0
De
pth
(c
m)
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-60
-40
-20
0
Brussels 1Brussels 2Brussels 3Brussels 4Brussels 5
Ice Salinity (-)
0 2 4 6 8 10 12 14
De
pth
(c
m)
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-60
-40
-20
0
Brussels 1Brussels 2
Ice Salinity (-)
0 2 4 6 8 10 12 14
De
pth
(c
m)
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-60
-40
-20
0
Brussels 1Brussels 2Brussels 3
Ice Salinity (-)
0 2 4 6 8 10 12 14
De
pth
(c
m)
-80
-60
-40
-20
0
Brussels 1Brussels 2Brussels 3Brussels 4
Ice Salinity (-)
0 2 4 6 8 10 12 14
De
pth
(c
m)
-80
-60
-40
-20
0
Brussels 1Brussels 2Brussels 3Brussels 4Brussels 5
Brine Salinity (-)
0 20 40 60 80 100 120
De
pth
(c
m)
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-60
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0
Brussels 1Brussels 2
Brine Salinity (-)
0 20 40 60 80 100 120
De
pth
(c
m)
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0
Brussels 1Brussels 2Brussels 3
Brine Salinity (-)
0 20 40 60 80 100 120
De
pth
(c
m)
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0
Brussels 1Brussels 2Brussels 3Brussels 4
Brine Salinity (-)
0 20 40 60 80 100 120
De
pth
(c
m)
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-60
-40
-20
0
Brussels 1Brussels 2Brussels 3Brussels 4Brussels 5
Relative brine volume (%)
0 10 20 30 40
De
pth
(c
m)
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-60
-40
-20
0
Brussels 1
Relative brine volume (%)
0 10 20 30 40
De
pth
(c
m)
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0
Brussels 1Brussels 2
Relative brine volume (%)
0 10 20 30 40
De
pth
(c
m)
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0
Brussels 1Brussels 2Brussels 3
Relative brine volume (%)
0 10 20 30 40
De
pth
(c
m)
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-60
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0
Brussels 1Brussels 2Brussels 3Brussels 4
Relative brine volume (%)
0 10 20 30 40
De
pth
(c
m)
-80
-60
-40
-20
0
Brussels 1Brussels 2Brussels 3Brussels 4Brussels 5
Thermodynamics at Brussels Site (unflooded)Thermodynamics at Brussels Site (unflooded)
Ice Temperature (°C)
-7 -6 -5 -4 -3 -2 -1 0
Dep
th (
cm
)-80
-60
-40
-20
0
Brussels 1
[ Chlorophyll a ] (µg / l)
0 5 10 15 20 25
Dep
th (
cm)
-80
-60
-40
-20
0
[ DMS ] (nmol / kg ice )
0 500 1000 1500 2000 2500 3000 3500
[Chla] - Brussels 1[DMS] - Brussels 1
[ Chlorophyll a ] (µg / l)
0 5 10 15 20 25
Dep
th (
cm)
-80
-60
-40
-20
0
[ DMSP ] (nmol / kg ice )
0 1000 2000 3000 4000 5000 6000
[Chla] - Brussels 1[DMSP] - Brussels 1
Ice Temperature (°C)
-7 -6 -5 -4 -3 -2 -1 0
Dep
th (
cm
)-80
-60
-40
-20
0
Brussels 1Brussels 2
[ Chlorophyll a ] (µg / l)
0 5 10 15 20 25
Dep
th (
cm)
-80
-60
-40
-20
0
[ DMSP ] (nmol / kg ice )
0 1000 2000 3000 4000 5000 6000
[Chla] - Brussels 2[DMSP] - Brussels 2
[ Chlorophyll a ] (µg / l)
0 5 10 15 20 25
Dep
th (
cm)
-80
-60
-40
-20
0
[ DMS ] (nmol / kg ice )
0 500 1000 1500 2000 2500 3000 3500
[Chla] - Brussels 2[DMS] - Brussels 2
Ice Temperature (°C)
-7 -6 -5 -4 -3 -2 -1 0
Dep
th (
cm
)-80
-60
-40
-20
0
Brussels 1Brussels 2Brussels 3
[ Chlorophyll a ] (µg / l)
0 5 10 15 20 25
Dep
th (
cm)
-80
-60
-40
-20
0
[ DMSP ] (nmol / kg ice )
0 1000 2000 3000 4000 5000 6000
[Chla] - Brussels 3[DMSP] - Brussels 3
[ Chlorophyll a ] (µg / l)
0 5 10 15 20 25
Dep
th (
cm)
-80
-60
-40
-20
0
[ DMS ] (nmol / kg ice )
0 500 1000 1500 2000 2500 3000 3500
[Chla] - Brussels 3[DMS] - Brussels 3
Ice Temperature (°C)
-7 -6 -5 -4 -3 -2 -1 0
Dep
th (
cm
)-80
-60
-40
-20
0
Brussels 1Brussels 2Brussels 3Brussels 4
[ Chlorophyll a ] (µg / l)
0 5 10 15 20 25
Dep
th (
cm)
-80
-60
-40
-20
0
[ DMSP ] (nmol / kg ice )
0 1000 2000 3000 4000 5000 6000
[Chla] - Brussels 4[DMSP] - Brussels 4
[ Chlorophyll a ] (µg / l)
0 5 10 15 20 25
Dep
th (
cm)
-80
-60
-40
-20
0
[ DMS ] (nmol / kg ice )
0 500 1000 1500 2000 2500 3000 3500
[Chla] - Brussels 4[DMS] - Brussels 4
Ice Temperature (°C)
-7 -6 -5 -4 -3 -2 -1 0
Dep
th (
cm
)-80
-60
-40
-20
0
Brussels 1Brussels 2Brussels 3Brussels 4Brussels 5
[ Chlorophyll a ] (µg / l)
0 5 10 15 20 25
Dep
th (
cm)
-80
-60
-40
-20
0
[ DMSP ] (nmol / kg ice )
0 1000 2000 3000 4000 5000 6000
[Chla] - Brussels 5[DMSP] - Brussels 5
[ Chlorophyll a ] (µg / l)
0 5 10 15 20 25
Dep
th (
cm)
-80
-60
-40
-20
0
[ DMS ] (nmol / kg ice )
0 500 1000 1500 2000 2500 3000 3500
[Chla] - Brussels 5[DMS] - Brussels 5
DMS(P) and Chla evolution at Brussels SiteDMS(P) and Chla evolution at Brussels Site
[Chla] measurements by I. Dumont, [Chla] measurements by I. Dumont, C. Fritsen, B. SaundersC. Fritsen, B. Saunders
Liège Site IMB
Colder Air Temperatures don’t penetrate thick snow cover
Snow/Ice Interface continuouslyflooded with sea water
Sea Ice relatively isothermal
Irregular ice bottom affects sonarreturns. Bottom pinger reset whenCTD removed for repairs.
Ice Temperature (°C)
-7 -6 -5 -4 -3 -2 -1 0
De
pth
(c
m)
-120
-100
-80
-60
-40
-20
0
Liège 1
[ Chlorophyll a ] (µg / l)
0 5 10 15 20
Dep
th (
cm)
-120
-100
-80
-60
-40
-20
0
[ DMSP ] (nmol / kg ice )
0 1000 2000 3000 4000
[Chla] - Liège 1[DMSP] - Liège 1
[ Chlorophyll a ] (µg / l)
0 5 10 15 20
Dep
th (
cm)
-120
-100
-80
-60
-40
-20
0
[ DMS ] (nmol / kg ice )
0 500 1000 1500 2000
[Chla] - Liège 1[DMS] - Liège 1
Ice Temperature (°C)
-7 -6 -5 -4 -3 -2 -1 0
De
pth
(c
m)
-120
-100
-80
-60
-40
-20
0
Liège 1Liège 2
[ Chlorophyll a ] (µg / l)
0 5 10 15 20
Dep
th (
cm)
-120
-100
-80
-60
-40
-20
0
[ DMSP ] (nmol / kg ice )
0 1000 2000 3000 4000
[Chla] - Liège 2[DMSP] - Liège 2
[ Chlorophyll a ] (µg / l)
0 5 10 15 20
Dep
th (
cm)
-120
-100
-80
-60
-40
-20
0
[ DMS ] (nmol / kg ice )
0 500 1000 1500 2000
[Chla] - Liège 2[DMS] - Liège 2
Ice Temperature (°C)
-7 -6 -5 -4 -3 -2 -1 0
De
pth
(c
m)
-120
-100
-80
-60
-40
-20
0
Liège 1Liège 2Liège 3
[ Chlorophyll a ] (µg / l)
0 5 10 15 20
Dep
th (
cm)
-120
-100
-80
-60
-40
-20
0
[ DMSP ] (nmol / kg ice )
0 1000 2000 3000 4000
[Chla] - Liège 3[DMSP] - Liège 3
[ Chlorophyll a ] (µg / l)
0 5 10 15 20
Dep
th (
cm)
-120
-100
-80
-60
-40
-20
0
[ DMS ] (nmol / kg ice )
0 500 1000 1500 2000
[Chla] - Liège 3[DMS] - Liège 3
Ice Temperature (°C)
-7 -6 -5 -4 -3 -2 -1 0
De
pth
(c
m)
-120
-100
-80
-60
-40
-20
0
Liège 1Liège 2Liège 3Liège 4
[ Chlorophyll a ] (µg / l)
0 5 10 15 20
Dep
th (
cm)
-120
-100
-80
-60
-40
-20
0
[ DMSP ] (nmol / kg ice )
0 1000 2000 3000 4000
[Chla] - Liège 4[DMSP] - Liège 4
[ Chlorophyll a ] (µg / l)
0 5 10 15 20
Dep
th (
cm)
-120
-100
-80
-60
-40
-20
0
[ DMS ] (nmol / kg ice )
0 500 1000 1500 2000
[Chla] - Liège 4[DMS] - Liège 4
Ice Temperature (°C)
-7 -6 -5 -4 -3 -2 -1 0
De
pth
(c
m)
-120
-100
-80
-60
-40
-20
0
Liège 1Liège 2Liège 3Liège 4Liège 5
[ Chlorophyll a ] (µg / l)
0 5 10 15 20
Dep
th (
cm)
-120
-100
-80
-60
-40
-20
0
[ DMSP ] (nmol / kg ice )
0 1000 2000 3000 4000
[Chla] - Liège 5[DMSP] - Liège 5
[ Chlorophyll a ] (µg / l)
0 5 10 15 20
Dep
th (
cm)
-120
-100
-80
-60
-40
-20
0
[ DMS ] (nmol / kg ice )
0 500 1000 1500 2000
[Chla] - Liège 5[DMS] - Liège 5
DMS(P) and Chla evolution at Liège SiteDMS(P) and Chla evolution at Liège Site
[Chla] measurements by I. Dumont, [Chla] measurements by I. Dumont, C. Fritsen, B. SaundersC. Fritsen, B. Saunders
Radiometer indicateschanges in irradiance,snow cover thickness, biological growth
Opening and closing ofLeads in the ice
Breakup of the ice floe where IMBsseparate and driftindependently
SIMBA Accomplishments
Antarctic sea ice is a springtime “Biogeochemical Reactor” Driven by Physical Feedback, where thermal changes drive porosity and convection, leading to:
• Nutrient Flux =>Enhanced Biological Productivity• Biological Degradation=>DMSP+DMS Flux • Porosity Changes=>CO2 Exchanges• Shelf Sediments and Iceberg Melting as Iron
sources
The Sea Ice CO2 Pump
A long lived dogma…
Weiss et al 1979, Gordon et al 1984, Poisson
and Chen 1987
« Weddell Sea pack ice effectively
blocks the air-sea exchange of gases »
No evidence of marked ventilation is
found in deep waters of the Weddel Sea.
Thus sea ice appears to prevent air-sea
exchange.
A long lived dogma challenged?…
Golden et al., 1998
Theoretical and experimental
evidence that sea ice permeability
increases considerably above -
5°C, the so-called “law of fives”
(Golden et al., 1998. Science 282:
2238)
Science 282: 2238
Kelley & Gosink 1970s-80s« unlike ices from pure freshwater, sea ice is a highly permeable
medium for gases »They found rate of CO2 penetration about 60 cm h-1 at -7°C
« gas migration through sea ice is an important factor in ocean-atmosphere winter communication particularly when the surface temperature is > -10° » (Gosink et al., 1976. Nature 263: 41)
Sea Ice Phase Diagram
CaCO3 dissolution/precipitation
Thompson and Nelson 1956 showed that at a temperature just below the freezing point calcium carbonate begins to precipate from the entrained brines in sea ice and remains in the ice.
Weiss et al 1979 observed alkalinity anomalies in the surface water of the Weddell Sea
Jones et al. 1983 observed a transfer of CaCO3 from the ice to surface waters in the Arctic Ocean
Papadimitriou et al. 2004 and Dieckmann et al. observed CaCO3 precipitation in artificial and natural sea ice and identified it as Ikaite
Rysgaard et al. 2007 suggested that CaCO3 precipitation in sea ice might act as a sink for CO2.
2HCO3- + Ca2+ CaCO3 + CO2
2HCO3- + Ca2+
CaCO3 + CO2
CO2
In winter, precipitation of In winter, precipitation of CaCOCaCO33 occurs within sea occurs within sea ice. ice. Produced COProduced CO22 is expelled is expelled with brine, while CaCOwith brine, while CaCO33 is is trapped within brine trapped within brine channelschannels
Brine sink rapidly carrying Brine sink rapidly carrying COCO2 2 (see Brine Drainage (see Brine Drainage Slide)Slide)
Part of COPart of CO22 which passes which passes below the pycnocline is below the pycnocline is « removed » from the « removed » from the system.system.
fall/winterfall/winter
SEA ICE PUMPSEA ICE PUMPA potential abiotic CaCOA potential abiotic CaCO33 Carbon source Carbon source
Is COIs CO22 released to the released to the atmosphere anytime atmosphere anytime new ice forms?new ice forms?(Answer on Next Slide)(Answer on Next Slide)
D. Nomura, 2006D. Nomura, 2006
4545
Rysgaard et al., 2007, Delille et al., in prep.Rysgaard et al., 2007, Delille et al., in prep.
Upward CO2 Flux over New Ice at the SIMBA site
A B C D E-2.5
0.0
2.5
5.0over iceover snow
Air
-ic
e C
O2 f
lux
es
(mm
ol m
-2d
-1)
-9
-8
-7
-6
-5
-4
Inte
rfa
ce t
emp
era
ture
(°C
)
Figure 17:Temperature at the ice interface and CO2 fluxes over ice and snow (positive fluxes correspond to efflux to the atmosphere) at 5 sites of the second "frost flowers" station.
Brine Drainage at SIMBA
2HCO3- + Ca2+
CaCO3 + CO2
CaCO3 + CO2
2HCO3- + Ca2+
CO2
CO2
In spring, CaCOIn spring, CaCO33 trapped within sea ice trapped within sea ice dissolves. This dissolves. This process consumes process consumes COCO2.2.
Budget of winter Budget of winter and spring processes and spring processes is a net sink of COis a net sink of CO2.2. It It depends on:depends on:
ratio of CaCOratio of CaCO33 trapped vs COtrapped vs CO22 expelled (?)expelled (?)
quantity of COquantity of CO22 which pass below the which pass below the pycnocline during the pycnocline during the autumn-winter (?)autumn-winter (?)
fall/winterfall/winter springspring
GAS COMPOSITION IN SEA ICEGAS COMPOSITION IN SEA ICEA potential abiotic CaCOA potential abiotic CaCO33 Carbon pump Carbon pump
4646
Rysgaard et al., 2007, Delille et al., in prep.Rysgaard et al., 2007, Delille et al., in prep.
Sea ice exhibits marked CO2 dynamics controlled by (i) salinity (ii) precipitation/dissolution of CaCO3 and (iii) primary production
CaCO3 precipitation occurs within sea ice and can be a very efficient pathway for atmsopheric CO2 uptake
Sea ice in spring exchanges CO2 with the atmosphere. Sea ice acts first as a source of CO2 to the atmosphere then as a sink.
This spring sink of the antarctic sea ice is about -0.025 PgC yr. It would represent an additional sink of 50% to the CO2 sink of the Southern Ocean
Taking into account CaCO3 precipitation and particular sea-ice processes especially discrepency in salt:gas rejection (loose et al. 2009) and possible artefacts in the transcient hallogen tracers, it might deserve to revisite C anthropogenic computation in sea ice covered waters
Conclusions
Where are we?
• Strong Coupling between the biogeochemistry and physics of the ice, related to growth, thermal driving, snow
• Climatically active gases, DMS and CO2, are important new developments
• Time series from IMBs with additional sensors like radiometers, oxygen, pCO2 look important
• Modeling of fluid flow looks critical• Subtle differences in conditions can lead to big
differences in the biogeochemistry
It’s been fun
Thanks to Elizabeth for the invite.
GAS COMPOSITION IN SEA ICEGAS COMPOSITION IN SEA ICECOCO22 : the ”trouble maker” : the ”trouble maker”
SummarySummary
• pCOpCO22 is a is a difficult variable to measuredifficult variable to measure in the sea ice environment in the sea ice environment• a suite of a suite of measurement techniques are still in developmentmeasurement techniques are still in development and and
in the need of proper validationin the need of proper validation• pCOpCO22 is generally is generally supersaturatedsupersaturated in most of the sea ice cover in most of the sea ice cover
during the during the winterwinter• pCOpCO22 is highly is highly undersaturatedundersaturated in the whole sea ice cover during in the whole sea ice cover during
spring and spring and summersummer• Potential and concurrent mechanismsPotential and concurrent mechanisms for the pCO for the pCO22 drawdown drawdown
during the summer are:during the summer are:Dilution of brinesDilution of brinesDissolution of calcium carbonateDissolution of calcium carbonatePrimary ProductionPrimary Production
• There is a potential There is a potential inorganic CaCOinorganic CaCO33 CO CO22 pump pump associated to sea associated to sea
ice growth and decayice growth and decay
4848
From land fast sea ice to multiyear pack ice
Ispol drift experimentR.V. PolarsternNov-Dec 2004First and multi-year pack ice
AA03-V1 cruiseR.V. Aurora AustralisSep-Oct 2003First year pack ice
Simba drift experimentR.V. N.B. PalmerOct 2007First year pack ice
66°3
9' S
66°3
8‘30
S66
°38’
S
Delille al. , 2007
GAS COMPOSITION IN SEA ICEGAS COMPOSITION IN SEA ICECOCO22 : the ”trouble maker” : the ”trouble maker” Balancing the effects…Balancing the effects…
Dumont d’Urville, 1999Dumont d’Urville, 1999It works!...and all three processes contribute!It works!...and all three processes contribute!
(from Solubility equations)(from Solubility equations)
(from Oxygen production)(from Oxygen production)
(from Total alcalinity anomaly)(from Total alcalinity anomaly)
4747
Key processes ? (Sal brine > sal seawater)
-8 -7 -6 -5 -4 -3 -2 -10
250
500
750
1000 AA 2003/V1 Ispol
atmospheric
concentration
sea ice temperature (°C)
pC
O2 (
pp
m)
-8 -7 -6 -5 -4 -3 -2 -10
250
500
750
1000 AA2003 Ispol
atmospheric
concentration
sea ice temperature (°C)
pC
O2 (
pp
m)
-8 -7 -6 -5 -4 -3 -2 -10
250
500
750
1000 spring summer
dilution effect
sea ice temperature (°C)
pC
O2 (
pp
m)
Key processes ? (Sal brine > sal seawater)
-8 -7 -6 -5 -4 -3 -2 -10
25
50
75
100
125
sea ice temperature (°C)
Sa
linit
y
-8 -7 -6 -5 -4 -3 -2 -10
500
1000
1500
2000
2500
3000
3500
sea ice temperature (°C)
TA
35
(µm
ol k
g-1
)
-8 -7 -6 -5 -4 -3 -2 -175
100
125
150
saturation
sea ice temperature (°C)
O2 (
% s
atu
rati
on
)
Air-ice gas transfer
PermeableImpermermeable
Scaled using sea ice temperature derived from the NEMO-LIM model
Spring air-ice fluxes of COSpring air-ice fluxes of CO22 for the Antarctic sea ice cover is assessed to - for the Antarctic sea ice cover is assessed to -
0.025 PgC from October to December0.025 PgC from October to December
mmol m² d-1
CO2 fluxes
Spring antarctic sea ice cover would represent an additional sink of about Spring antarctic sea ice cover would represent an additional sink of about 50% of the overall CO50% of the overall CO22 sink of the Southern Ocean sink of the Southern Ocean
Air-ice fluxes:Air-ice fluxes:-0.025 Pg-0.025 Pg
Air-sea fluxes south of 50°S:Air-sea fluxes south of 50°S:-0.05 Pg yr-1-0.05 Pg yr-1
Independent assessment
related CO2 transfer
from the atmosphere
(mmol m-2)
temperature increase and related dilution
-60
Primary production -25
CaCO3 dissolution -57
Estimates of potential air-ice CO2 fluxes related to spring and summer physical and biogeochemical processes observed during the 2003/V1 and ISPOL cruises. Flux representative of a 4 months period.The overall CO2 fluxes reach 142 mmol m-2.
Taking into account a mean value for the Antarctic sea ice edge surface area of 16×106 km2, the corresponding overall CO2 fluxes account for 0.029 PgC.
This compares favourably with our previous estimate of an additional sink of 0.025 PgC.
Sea ice exchanges CO2 with the atmosphere
Semiletov et al. 2004
Semiletov et al. 2007
Zemelink et al. 2006
Zemelink et al. 2006
Semiletov et al. 2004
Semiletov et al. 2007
Nomura et al. T2-017
Nomura et al. T2-017
Heineschet al.
Heinesch et al. This study
This study
Back of the envelope computation
Semiletov et al. 2004
Semiletov et al. 2007
Zemelink et al. 2006
Zemelink et al. 2006
Semiletov et al. 2004
Semiletov et al. 2007
Nomura et al. T2-017
Nomura et al. T2-017
Heineschet al.
Heinesch et al. This study
This study
-1 gC m-2 month-1
Back of the envelope computation
-1 gC m-2 month-1Raw mean of spring air-ice CO2 fluxesSpring surface of antarctic sea ice cover
20* 106 km²
Time length of fluxes 2 months
Overall spring antarcticair-ice CO2 fluxes - 0.04 PgC yr-1
Overall S.O. open water fluxes (Takahashi et al. 2009)
- 0.05 PgC yr-1