Sea Ice Walt Meier Contributors to Sea Ice Section: J. Comiso, F. Nishio, T. Agnew, J. Yackel, M. Tschudi, R. Kwok, R. DeAbreu, J. Falkingham 3rd IGOS Cryosphere Theme Workshop, Noordwijk, 16 – 18 October 2006

Importance of Sea Ice Observations Climate –Albedo feedback –Heat/moisture transfer between ocean and atmosphere –Salt flux between ice and ocean –Key indicator of current climate change in the Arctic Modeling – GCM, regional, forecasting Operations – navigational safety Indigenous populations Wildlife Sep Sep SSM/I, Passive Microwave

Sea Ice Parameters Extent/Edge Concentration Motion, Mass/Volume Transport Melt Onset, Length of Melt Season Age/Stage of Development Thickness, thickness distribution Snow Depth on Sea Ice Leads and Polynyas New Ice Formation (Brine Formation) Meltponds Deformation Ridges, Density/Height Floe Size and Distribution Brine Volume/Frost Flowers/Snow Grain size Chemistry and nutrient parameters (?) Icebergs Large-Scale Small-Scale Radarsat, SAR

Current Capabilities Satellites Passive Microwave and Scatterometer, 10 – 50 km, daily –Large-scale extent, concentration, motion –Some info on ice age, edge –Snow depth (unvalidated) –Melt onset and freeze-up –Large iceberg tracking Visible/Infrared, 0.25 – 5 km, daily (limited by clouds) –Albedo, temperature –Thickness of thin ice –Some meltpond info (from high res.) –Medium to large iceberg tracking SAR, 0.1 – 0.5 km, 1-3 days –Motion, deformation, ridging, leads, new ice –Inference of FYI thickness –Can be difficult to interpret imagery –Surface roughness –Medium to large iceberg tracking Altimeter, 0.1 km, monthly composite, once per season –Sea ice and snow freeboard (laser), uncertainty converting to total thickness –Surface roughness – ridging, snow properties (?) –Medium to large iceberg height?

Current Capabilities Surface/Near-Surface Buoys, IABP and IBAP –Large-scale motion, met. conditions –30-40 in Arctic, fewer in Antarctic –Mass balance buoys in Arctic (<10) – snow depth, internal/bottom temperatures, fluxes Surface ships –Ice observations (ASPeCT standard, only applied in SH so far) Submarine –Historical thickness, no recent data –AUVs show promise for thickness Aircraft –Reconnaissance for ice edge/concentration –Iceberg tracking –UAVs for temperature, meltponds, leads, possibly thickness with altimeters Operational ice charts – integrate a variety of data sources for ice edge, concentration, age, thickness –Weekly or bi-weekly –Effective spatial resolution and quality varies depends on quality/quantity of data available

Operational vs. Climate Operational needs best possible information – new technologies can immediately be taken advantage of –Timeliness is key for products For climate records, consistency is more important than accuracy – tracking interannual variability and trends –Consistent algorithms, sensor frequencies –Inter-sensor calibration is key –New technologies could be used for improved reanalyses

Sea Ice Extent Climate Records PM Only Fused/ Operational (NIC charts, HadleyISST)

Sea Ice Extent Climate Records Passive Microwave

Sea Ice Thickness Altimeters providing first dense basin-scale thickness coverage New technology, not proven for sea ice Uncertainties converting from freeboard to thickness (e.g., snow cover) Combining with SAR yields enhanced results (R. Kwok) Still limited temporal coverage (seasonal to annual), but enough? CryoSat-2 in 2009 ICESat-2? Recovery of historical records? Lead

Parameter CTOCTO Measurement Range Measurement AccuracyResolution Comment / Principal Driver SpatialTemporal LHUVUVUVU Extent/Edge Ccl Cop NA km km km 1313 dayAMSR TNA km10km10km1dayCMIS Ocl Oop NA km km km 1111 day CMIS SAR Concentration Ccl Cop 0100%5-20%15km1day AMSR, high summer errors T0100%<10%15km1day O0100%<5%10km1day Motion Ccl Cop 0100km day km day km 1313 day AMSR SAR T0100km day km1day Ocl Oop 0100km day km day km 1111 day More frequent SAR coverage Thickness Ccl Cop 050m m%m% 0.5 km year week ICESat ops ice charts T050m Ocl Oop 050m m%m% km 1111 mnth day sat. altimeter Snow Depth on Ice Ccl0100cm10-20cm15km1dayAMSR T0100cm5 10km1day Ocl0100cm2 5km1day

Parameter CTOCTO Measurement Range Measurement AccuracyResolution Comment / Principal Driver SpatialTemporal LHUVUVUVU Melt Onset, Duration of Melt Ccl1365jday4days15km1dayAMSR T1365jday2days15km1day Ocl1365jday1day10km1day Surface Albedo Ccl0100%10%1km1day MODIS, but not currently produced T0100%10%1km1day Ocl0100%1-5%0.5km1day Meltpond Coverage Ccl0100%10%1km1day MODIS, but not fully developed T0100%5%0.5km1day Ocl0100%5%0.1km1day Leads/polynyas Ccl Cop indet. % km % km km 1111 day week AMSR SAR T Ocl Oop indet. % km % km km 1111 dayMODIS, PM Volume/Mass Flux Ccl Currently no regular needed thickness est. T Ocl0indet.km 3 day- 1 1 km 3 day -1 25km1day

Priority Observations 1 Continued passive microwave sensor [snow] –Consistent with current sensors for trends –Algorithm evaluation and development, fusion (of algorithms and with other sensor – e.g., scatterometer) –Reanalysis to create CDR quality record, error estimates –Biases in summer and thin ice regions Further development of altimeters for thickness [ice sheets] Continued SAR for operations, small-scale motion and deformation [ice sheets] Arctic Sea Ice Extent

Priority Observations 2 Continued support of buoys, including more mass balance buoys –Calibration/validation of satellite/models Further development of autonomous surface and near-surface observations for calibration, validation, and small-scale variability –UAVs and AUVs –Buoys, esp. mass balance Visible/IR continuity – albedo, etc. MODIS, Visible

Priority Activities Passive microwave analysis/reanalysis [snow] Resolve different algorithms, better intersensor calibration, ground truthing for different surface types and spatial scales –Especially concentration, also motion, melt Solidify error estimates and error covariance [all] Integration with models [all] –Produce fields most useful to models, data assimilation Data Fusion [all] –e.g., active/passive microwave + vis/IR + SAR + altimeter + buoys + ??? Develop reliable thickness/roughness products from satellite altimeters [ice sheets] Recover historical records and integrate with more recent records (e.g., observations from field expeditions, etc.) [all] Data documentation (metadata) and distribution, IPY-DIS to start? [all]

Outstanding Issues Values in requirements table need to be nailed down Iceberg table very rough, unsure of many values What’s missing in text? What in text is too much? –Operational vs. climate –Large-scale vs. small-scale (how small?) Cross-over with other chapters Integration with other documents (GCOS) Need images and image suggestions Where do ice shelves belong? SSM/I, Passive Microwave

Thanks!

Iceberg Capabilities and Requirements ParameterHorizontal resolution Vertical resolution Temporal resolution AccuracyLatencyComments Limit of Iceberg Area 10 km-12 hours10%2 hoursMost important parameter to avoid icebergs Concentration of Icebergs 1 degree of latitude and longitude -12 hours10%2 hoursNumber of icebergs in a given area – ship route Planning Position1 km-1 hour10%0.5 hourCollision avoidance Size1-10 m 24 hours30%2 hoursInput to iceberg deterioration model; Iceberg towing (highest resolution) Draft-1-10 m24 hours30%2 hoursInput to iceberg drift model; Iceberg towing (highest res.) Mass--24 hours30%2 hoursCalculated Drift Velocity1 km/day-24 hours10%2 hoursCalculated