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Sea ice thickness from CryoSat – A new data set for operational ice services?

Sea ice thickness from CryoSat – A new data set for operational ice services?. Christian Haas German CryoSat Office AWI. First Earth Opportunity Mission, to be launched in November 2004.

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Sea ice thickness from CryoSat – A new data set for operational ice services?

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  1. Sea ice thickness from CryoSat – A new data set for operational ice services? Christian Haas German CryoSat Office AWI

  2. First Earth Opportunity Mission, to be launched in November 2004 • Selected after 1999 proposal from European Scientists Group, lead by Prof. D. Wingham, University Collage London, UK • Goals: • Observe changes in Arctic multi-year ice thickness • Observe changes of Antarctic and Greenland ice sheet thickness • Radar altimetry mission with new technology: Synthetic Aperture, Interferometric Radar Altimeter: SIRAL

  3. Ice Sheets Sea Ice h? h?

  4. Freeboard to Thickness Conversion • Estimate Freeboard above Interpolated Ocean surface • Conversion assumes reflection from the ice/snow interface • Conversion to thickness using climatology of snow depth/densities [Warren, 1999]

  5. Comparison of satellite and submarine thickness measurements ‘93 to ‘97 Observed thickness trends (ERS-2) (Laxon et al., 2003)

  6. h Time = 2*h/v Pulse-Limited Radar Altimetry

  7. Ocean Ice Sheets Sea Ice

  8. SIRAL: Synthetic-Aperture Interferometric Radar Altimeter SAR 250 m along track resolution InSAR

  9. SAR / InSAR / LBR Modes

  10. Orbit (Science Orbit): • 717 km Mean Altitude • 92° Inclination • 369 Days Repeat Cycle • 30 Days Subcycle • 7.5 km Inter-Track Spacing at Equator

  11. Nominal Ground Track of one Sub-Cycle

  12. Cross-overs per 104 km2 per year

  13. CryoSat Data Products Spatially & Temporally Averaged Ice Thickness Along-track Ice Elevations Multi-looked Beams & Phases Coherent Synthetic Beams ~ 1 Mbit/day ~ 400 Gbit/day ~ 3 Gbit/day ~ 20 Mbit/day ~ 400 Gbit/day Level 1 - 1b Level 2 - 3 Level 0 - 1 Level 1b - 2 Level 3 - 4 Coherent, Pulse-limited Radar Echoes Secular trend in ice thickness ~20kbit/day

  14. L0 - L1b Beam Formation & Steering

  15. Level 1B Multi-looked Echoes L0 - L1b Stack & Multi-looking Doppler Beam Stack Over Spherical Surface

  16. Simulated ‘SAR’ L1b - L2 Product

  17. Major improvements over ice surfaces due to synthetic-aperture interferometric (InSAR) processing Data is orbit oriented (not imaging) Low point-to-point covariance due to speckle  Most reliable for 104 km2 spatial / 1 month temporal resolution Access to data through ESA Data-AOs Uncertainties will be addressed by extensive validation Conclusions See you at: http://www.cryosat.de

  18. Sea ice freeboard retrieval

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