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Sea Ice

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

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Sea Ice

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  1. 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

  2. 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 1979-1983 Sep 2002-2006 SSM/I, Passive Microwave

  3. 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

  4. Current CapabilitiesSatellites • 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?

  5. Current CapabilitiesSurface/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

  6. 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

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

  8. Sea Ice Extent Climate Records Passive Microwave

  9. Lead 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?

  10. 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

  11. 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

  12. 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]

  13. 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

  14. Thanks!

  15. Iceberg Capabilities and Requirements

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