Transcript Wednesday_6_Manizza_ICESOCCS.pptx

Understanding the Role of Sea-Ice
in the
Southern Ocean CO2 sink
Manfredi Manizza
[email protected]
Scripps Institution of Oceanography
University of California - San Diego
Outline
1) Intro – SO C-Cycle : BGC Processes & Sea-ice
2) Sea-Ice & Ocean physics  C-Cycle
3) Sea-Ice & Iron  C-Cycle
4) Sea-Ice & Air-sea gas exchange  C-Cycle
5) Questions for future work
Life in a (fizzy) freezer
Southern Ocean Food Web
N2O
3
2
CO2
1
Modified from Vancoppenolle et al. (2013)
1) Open Water
2) Marginal Ice Zone
3) Ice-covered zone
Southern Ocean Carbon Cycle
(From Princeton U.)
Ito et al. (2010)
(PgC yr-1)
Different trajectories of Polar Carbon Sinks - SO
Le Quéré et al.( 2007)
Wind dominant driver for CO2 uptake
Toggweiler & Russell (2008)
Different trajectories of Polar Carbon Sinks - SO
OBSERVATIONS
out
in
Air-sea CO2 fluxes
RECCAP, Lenton et al., 2013
Le Quéré et al.( 2007)
Antarctic Sea-ice : Current State
1979 - 2012
More Sea-Ice
Fractional Ice cover decade-1
Less Sea-Ice
King (2014)
Two Poles, Two Stories…
AR5, WG4, CRYOSPHERE
Sea-Ice control on SO C-Cycle
DIRECT CONTROL :
1) Air-sea gas exchange  Areas of CO2 Uptake
2) Irradiance & PP  C-Biological Pump
INDIRECT CONTROL :
1) Deep-water formation  CO2 sequestration
2) Freshwater/Salt  Stratification & Mixing
Sea- Ice
&
Ocean Physics
Antarctic Sea-ice & AABW Formation
Antarctic Sea-ice : Current State
1979 - 2012
More Sea-Ice
Fractional Ice cover decade-1
Less Sea-Ice
King (2014)
Sea- Ice
&
Iron
Iron Cycle & Sea ice in the Southern Ocean
From bigshouth.be
Iron & sea ice in the Southern Ocean
Fe release from sea-ice
into seawater
Fe included in the sea-ice model in an OCC model
Wang et al. (2014)
Fe uptake by sea-ice
from seawater
Iron & sea ice in the Southern Ocean
Diatoms
Small Phytoplankton
Wang et al. (2014)
Sea- Ice
&
Air-Sea Gas exchange
Just a Simple Lid ?
Flux = α K (ΔC) (1- γ)
γ
α = solubility factor
K = gas transfer velocity
ΔC = air-sea gas gradient
Loose et al., 2014
Moving forward
MECHANSIMS TO MODEL
1) Buoyancy/Stratification
2) Sea-Ice/Water Shear
3) Gravity Waves/ice floes
K = gas transfer velocity
(Loose et al., 2014)
MODEL INPUT PARAMETERS :
1)
2)
3)
4)
Wind Speed
Air-temperature
Sea-Ice velocity
Sea-Ice concentration
OGCM + C-CYLE MODEL
OF POLAR OCEANS
Still a long way to go…
Two Missing Processes :
1) Brine & CO2 rejection:
Deep water formation
process and CO2 uptake.
2) Sea-ice Decay & ALK release :
Enhances CO2 uptake at sea-ice
margin during summer melting
Rysgaard et al. (2011)
CONCLUSIONS & FUTURE DIRECTIONS
Sea-Ice can controls Southern Ocean CO2 uptake
with multiple processes (physics, chemistry, and biology)
Where/when/how do we measure in the ocean bgc
properties that help to understand processes and variabilty
based on the use of multiple tools (in-situ, argo floats,
satellites, elephant seals, etc.) ?
Best way to integrate Obs. and Models to understand how
changes in sea-ice will affect CO2 uptake in the SO ?