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Roger De Abreu, Matt Arkett, Dean Flett Canadian Ice Service

Evaluation of ALOS PALSAR for Operational Ice Monitoring Preliminary Observations. Roger De Abreu, Matt Arkett, Dean Flett Canadian Ice Service Pablo Clemente-Colón, Sean Helfrich, Brian Melchior U.S. National Ice Center. Outline. Overview of PALSAR L-Band Expectations

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Roger De Abreu, Matt Arkett, Dean Flett Canadian Ice Service

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  1. Evaluation of ALOS PALSAR for Operational Ice Monitoring • Preliminary Observations Roger De Abreu, Matt Arkett, Dean Flett Canadian Ice Service Pablo Clemente-Colón, Sean Helfrich, Brian Melchior U.S. National Ice Center

  2. Outline • Overview of PALSAR • L-Band Expectations • Motivation, Obectives • Data Collection • Preliminary Observations • Final Words

  3. PALSAR Overview ScanSAR Modes Only • Launched October 2006 • L-Band SAR PALSAR • Primary difference is wavelength • Strong basis for comparison of ScanSAR modes

  4. Expectations for L-Band • Dierking and Busche (TGARS, 2006) -- Sea Ice Monitoring by L-Band SAR: An Assessment Based on Literature and Comparisons of JERS-1 and ERS-1 Imagery • L-Band and C-Band SAR Scattering Signature of Sea Ice for Operational Applications -- Son Nghiem, JPL, 2007. • Very good at mapping ice deformation, e.g. ridges, rubble fields • Better penetration into sea ice could yield unique and complementary information to C-band information • L-band signatures are significantly less sensitive to wet snow than C-band • However, less capable of identifying thin ice and separating FYI and MYI, especially at high incidence angles.

  5. Study Objectives • Identify what unique and complementary sea ice information PALSAR can provide compared to C-band SARs (focus on RADARSAT-1) • Identify the role(s) PALSAR data could play in NAIS operational programs • Complementary role to RADARSAT? • Contingency role to C-band SARs? • Better understand the potential for future multi-frequency SAR platforms/missions

  6. Data Collection • Collect concurrent RADARSAT-1/2 and PALSAR ScanSAR image pairs • Collect seasonally over major operational ice regimes • Collect under range of wind conditions • Collect over various incidence angles and polarizations • Where possible, collect in situ data to support analysis

  7. Case Study Locations • 4 case studies from two PALSAR and R-1 pairs • All HH polarization • Collected June 10 (spring) and July 15/16 (smmer) • ASF Convert tool used to ingest and geoproject data

  8. R-1 Beaufort Sea 20070610 15:00:21 SWB HH

  9. PALSAR Beaufort Sea 20070610 20:41:12 WB1 HH

  10. June 10th 2007 Spring Thick FYI Regime (9+ Thick FYI w/ traces of old ice; Vast floes) ALOS-PALSAR RADARSAT-1 • Rough interfloe areas more apparent in wet conditions in L-band • Thick FYI floes more easily identifiable in L-Band

  11. R-1 Beaufort Sea 20070610 15:00:21 SWB HH R-1 Baffin Bay 20070715 22:14:27 SWA HH

  12. PALSAR Baffin Bay 20070716 2:13:57 WB1 HH

  13. July 15/16 2007 Summer FYI - MYI ALOS-PALSAR 2:13:57 UTC RADARSAT-1 22:14:27 UTC • Floes appear much more homogeneous in R-1 • PALSAR appears to provide considerable more contrast within and between floes • Aids in identifying FYI and MYI concentrations

  14. R-1 Beaufort Sea 20070610 15:00:21 SWB HH

  15. PALSAR Beaufort Sea 20070610 20:41:12 WB1 HH

  16. June 10th 2007 – Mackenzie Delta RADARSAT-1: 15:00:21 UTC ALOS-PALSAR: 20:41:12 UTC • Wet ice lost in clutter at C- band – Better at L-band • Need to understand the ocean clutter better

  17. R-1 July 15, 2007 22:14:27 SWA HH R-1 Feb. 25, 2007 21:56 SWB

  18. PALSAR July 16, 2007 2:13:57 WB1 HH R-1 July 15, 2007 22:14:27 SWA HH

  19. PALSAR July 16, 2007 2:13:57 WB1 HH R-1 July 15, 2007 22:14:27 SWA HH • L-band has better penetration in melt conditions • Improved separation of second year ice from FYI

  20. Summary • Preliminary examination of summer scenes indicates that PALSAR does appear to be “seeing” more of the ice surface under wet snow • In melt conditions, when C-band monitoring is challenged, PALSAR appears to do a better job typing and characterizing ice. • Better floe definition in FYI and MYI regimes • Better separation of FYI and MYI floes

  21. Next Steps • Quantitatively characterize these differences • Involve ice analysts to further/validate visual assessment • Extend to PALSAR VV data • Incorporate R-2 data (HH/HV) and possibly TerraSAR X. • Collect field-validated datasets – e.g. Southern Beaufort Sea – IPY CFL. • Focus on winter freeze-up and PALSAR’s ability to type thin ice types • Collect and analyze Great Lakes dataset • Icebergs in ice

  22. Acknowledgements • CIS JAXA AO --- Evaluation of L-Band ScanSAR Data for Regional Ice Monitoring in Support of Navigation • NESDIS/NIC AO • Alaska SAR Facility – ALOS North American Node

  23. Extra Slides

  24. Analysis Objectives Separately and combined with C-band, assess PALSAR’s ability to: • Separate sea ice from open water • Type (classify) sea ice over a broad range of thicknesses • Provide other information • floe size, floe shape • surface deformation • surface melt conditions Focus on situations where C-band does not work well • Spring and summer ice typing • Ice and water separation under windy conditions

  25. Analysis Methodology • Pre-launch assessment of L-band SAR based on airborne data sets and backscatter modelling Completed -- L-Band and C-Band SAR Scattering Signature of Sea Ice for Operational Applications -- Son Nghiem, JPL, 2007.

  26. Nghiem, JPL, 2007 L-band modelled and observed backscatter

  27. Nghiem, JPL, 2007 C-band modelled and observed backscatter

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