Manfredi Manizza Scripps Institution of Oceanography University of California - San Diego Understanding the Role of Sea-Ice in the Southern Ocean CO 2 sink
Outline 2) Sea-Ice & Ocean physics C-Cycle 5) Questions for future work 1) Intro – SO C-Cycle : BGC Processes & Sea-ice 3) Sea-Ice & Iron C-Cycle 4) Sea-Ice & Air-sea gas exchange C-Cycle
Modified from Vancoppenolle et al. (2013) Life in a (fizzy) freezer N2ON2O Southern Ocean Food Web 1)Open Water 2)Marginal Ice Zone 3)Ice-covered zone CO 2
Southern Ocean Carbon Cycle Ito et al. (2010) (PgC yr -1 ) (From Princeton U.)
Different trajectories of Polar Carbon Sinks - SO Le Quéré et al.( 2007) Toggweiler & Russell (2008) Wind dominant driver for CO 2 uptake
Different trajectories of Polar Carbon Sinks - SO RECCAP, Lenton et al., 2013 OBSERVATIONS Air-sea CO 2 fluxes out in Le Quéré et al.( 2007)
Antarctic Sea-ice : Current State King (2014) Less Sea-Ice More Sea-Ice Fractional Ice cover decade -1
Two Poles, Two Stories… AR5, WG4, CRYOSPHERE
Sea-Ice control on SO C-Cycle DIRECT CONTROL : 1)Air-sea gas exchange Areas of CO 2 Uptake 2)Irradiance & PP C-Biological Pump INDIRECT CONTROL : 1)Deep-water formation CO 2 sequestration 2)Freshwater/Salt Stratification & Mixing
Sea- Ice & Ocean Physics
Antarctic Sea-ice & AABW Formation
Antarctic Sea-ice : Current State King (2014) Less Sea-Ice More Sea-Ice Fractional Ice cover decade -1
Sea- Ice & Iron
From bigshouth.be Iron Cycle & Sea ice in the Southern Ocean
Iron & sea ice in the Southern Ocean Fe included in the sea-ice model in an OCC model Fe release from sea-ice into seawater Fe uptake by sea-ice from seawater Wang et al. (2014)
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 ΔC = air-sea gas gradient α = solubility factor K = gas transfer velocity Loose et al., 2014
Moving forward K = gas transfer velocity MODEL INPUT PARAMETERS : 1)Wind Speed 2)Air-temperature 3)Sea-Ice velocity 4)Sea-Ice concentration MECHANSIMS TO MODEL OGCM + C-CYLE MODEL OF POLAR OCEANS 1)Buoyancy/Stratification 2)Sea-Ice/Water Shear 3)Gravity Waves/ice floes (Loose et al., 2014)
Still a long way to go… Rysgaard et al. (2011) 1)Brine & CO 2 rejection: Deep water formation process and CO 2 uptake. Two Missing Processes : 2) Sea-ice Decay & ALK release : Enhances CO 2 uptake at sea-ice margin during summer melting
CONCLUSIONS & FUTURE DIRECTIONS Sea-Ice can controls Southern Ocean CO 2 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 CO 2 uptake in the SO ?