EGU 2012, Kristine S. Madsen, High resolution modelling of the decreasing Arctic sea ice Kristine S. Madsen, T.A.S. Rasmussen, J. Blüthgen and M.H. Ribergaard Polar Oceanography, Danish Meteorological Institute Sea ice volume, m 3 Oil drift 17 days after initial spill

EGU 2012, Kristine S. Madsen, Overview Model introduction Sea ice changes –Extend –Volume –Ocean surface temperature Oil drift modelling –Surface spill –Deep spill –Importance of sea ice

EGU 2012, Kristine S. Madsen, HYCOM/CICE ocean and sea ice model North Atlantic and Arctic oceans ~10 km horizontal resolution Sea ice: dynamic and thermodynamic Ocean: hydrodynamic, 29 vertical levels (hybrid) ERA Interim atm. forcing, 2000–2009 Assimilate sea ice concentration and SST from satellite once a day, nudge towards climatological SSS

EGU 2012, Kristine S. Madsen, The CICE model Hibler-type elastic-viscous- plastic ice model Each grid cell has 5 ice thickness categories with 4 vertical layers for each, plus surface snow Horizontal resolution and time step same as ocean model (~10 km, 5 minutes)

EGU 2012, Kristine S. Madsen, Sea ice concentration Sea ice area (concentration ≥ 30%), m 2 ModelObservations Source: ocean.dmi.dk/arctic

EGU 2012, Kristine S. Madsen, Sea ice concentration Units: %

EGU 2012, Kristine S. Madsen, Sea ice concentrations – September 1 Observations Model Source (observations): U. of Illinois The Cryosphere Today Units: %

EGU 2012, Kristine S. Madsen, Sea ice thickness – September Units: m

EGU 2012, Kristine S. Madsen, Sea ice volume Units: m 3 Model

EGU 2012, Kristine S. Madsen, Ocean surface layer temperature Average for all ocean points north of 80°N, units °C

EGU 2012, Kristine S. Madsen, Ocean surface layer temperature Average for ocean points w. at least 30% ice, north of 80°N, units °C

EGU 2012, Kristine S. Madsen, Summary – sea ice The model reproduces concentration (within 10%) and timing of min and max sea ice concentration, but builds up ice too fast in the fall. The interannual variability is well represented. Sea ice volume shows continuous build-up from October to May and strong decrease in June shows large volume decrease and export along Greenland’s east coast and 2009 has lower ice volume than Summer polar ocean surface layer temperature is increased in summer 2007, also underneath the sea ice.

EGU 2012, Kristine S. Madsen, Oil drift modeling Existing hydrocarbon exploration & exploitation licences Applications for new licences 2012/13

EGU 2012, Kristine S. Madsen, DMI oil drift module Purposes: oil combating, “find the sinner”, drifting vessel, man overboard Particle model Passive advection with ocean current … and additional surface wind drift (3%) Wind speed is scaled inverse linear with sea ice concentration. Future work: Ocean speed is scaled inverse linear with sea ice concentration towards ice velocity. Buoyant rising (or sinking) Downward mixing by wind waves (scaled by wind speed + random distribution) Turbulent spreading (random walk scaled by current speed) Oil weathering 8 pre-defined oil-types - based on fractions of 8 hydrocarbons Instantaneous or continuous oil spill at any depth Runs operationally, 15 minutes response

EGU 2012, Kristine S. Madsen, Example of oil drift Imaginary surface spill on August south-east of Greenland 2 deg ~200 km

EGU 2012, Kristine S. Madsen, Ensemble oil drift setup – surface spill 5 spill positions. Continuous oil spill of 10 days duration and tracking extra 20 days giving 30 days simulation. 2 study periods: Aug/Sep and Oct/Nov 4 initial dates: 1, 11, 21, years: 2003–2009. … giving 28 ensemble members. … and a total of 280 simulations (10 types of oil).

EGU 2012, Kristine S. Madsen, Ensemble oil concentrations – surface spill Ribergaard et al., 2010 color scale 0-10 %

EGU 2012, Kristine S. Madsen, Ensemble oil concentrations – spill at 3000 m (bottom) Ribergaard et al., 2011 color scale 0-20 % color scale 0-10 %

EGU 2012, Kristine S. Madsen, Oil drift in sea ice affected areas Wind drag limited (already included in model) Oil will partly drift with the ice Oil will be trapped in pockets under the ice or freeze into the ice – reducing weathering

EGU 2012, Kristine S. Madsen, Summary – oil drift The simulated oil spill influenced the whole SW Greenland coast up to around Nuuk, while almost no oil ended up in SE Greenland.The simulated oil spill influenced the whole SW Greenland coast up to around Nuuk, while almost no oil ended up in SE Greenland. Larger spreading during Oct/Nov compared to Aug/Sep due to more windy conditions.Larger spreading during Oct/Nov compared to Aug/Sep due to more windy conditions. For deep spills, light oil types ascent to the surface within few days, while heavy oil types have about 20% settlement at the bottom and persistent occurrence of subsurface particles for months.For deep spills, light oil types ascent to the surface within few days, while heavy oil types have about 20% settlement at the bottom and persistent occurrence of subsurface particles for months. Sea ice will slow down the oil drift and limit the weathering.Sea ice will slow down the oil drift and limit the weathering.

EGU 2012, Kristine S. Madsen, Thank you! Sea ice volume, m 3 Oil drift 17 days after initial spill