Evaluation of ALOS PALSAR for Operational Ice Monitoring

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

North American Ice Service IICWG VIII – Frascati, Italy De Abreu et al. Outline • • • Overview of PALSAR L-Band Expectations Motivation, Obectives Data Collection Preliminary Observations Final Words

North American Ice Service IICWG VIII – Frascati, Italy PALSAR Overview Scan. SAR Modes Only • • Launched October 2006 L-Band SAR PALSAR Primary difference is wavelength Strong basis for comparison of Scan. SAR modes De Abreu et al.

North American Ice Service IICWG VIII – Frascati, Italy De Abreu et al. Expectations for L-Band • Dierking and Busche (TGARS, 2006) -- Sea Ice Monitoring by LBand SAR: An Assessment Based on Literature and Comparisons of JERS-1 and ERS-1 Imagery • L-Band 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.

North American Ice Service IICWG VIII – Frascati, Italy De Abreu et al. 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

North American Ice Service IICWG VIII – Frascati, Italy De Abreu et al. Data Collection • Collect concurrent RADARSAT-1/2 and PALSAR Scan. SAR 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

North American Ice Service IICWG VIII – Frascati, Italy De Abreu et al. 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

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

PALSAR Beaufort Sea 20070610 20: 41: 12 WB 1 HH

North American Ice Service IICWG VIII – Frascati, Italy De Abreu et al. June 10 th 2007 Spring Thick FYI Regime (9+ Thick FYI w/ traces of old ice; Vast floes) RADARSAT-1 ALOS-PALSAR • Rough interfloe areas more apparent in wet conditions in L-band • Thick FYI floes more easily identifiable in L-Band

R-1 R-1 Beaufort Baffin Sea Bay 20070610 20070715 22: 14: 27 15: 00: 21 SWASWB HH HH

PALSAR Baffin Bay 20070716 2: 13: 57 WB 1 HH

North American Ice Service IICWG VIII – Frascati, Italy July 15/16 2007 Summer FYI - MYI RADARSAT-1 22: 14: 27 UTC De Abreu et al. ALOS-PALSAR 2: 13: 57 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

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

North. PALSAR American Ice Service Beaufort Sea 20070610 20: 41: 12 WB 1 HH IICWG VIII – Frascati, Italy De Abreu et al.

North American Ice Service IICWG VIII – Frascati, Italy De Abreu et al. June 10 th 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

North American Ice Service IICWG VIII – Frascati, Italy De Abreu et al. R-1 July 15, 2007 22: 14: 27 SWA HH R-1 Feb. 25, 2007 21: 56 SWB

North American Ice Service IICWG VIII – Frascati, Italy De Abreu et al. R-1 July 15, 2007 22: 14: 27 SWA HH PALSAR July 16, 2007 2: 13: 57 WB 1 HH

North American Ice Service IICWG VIII – Frascati, Italy De Abreu et al. R-1 July 15, 2007 22: 14: 27 SWA HH PALSAR July 16, 2007 2: 13: 57 WB 1 HH • L-band has better penetration in melt conditions • Improved separation of second year ice from FYI

North American Ice Service IICWG VIII – Frascati, Italy De Abreu et al. 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

North American Ice Service IICWG VIII – Frascati, Italy Next Steps • • • De Abreu et al. 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 Terra. SAR 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

North American Ice Service IICWG VIII – Frascati, Italy Acknowledgements De Abreu et al. • CIS JAXA AO --- Evaluation of L-Band Scan. SAR Data for Regional Ice Monitoring in Support of Navigation • NESDIS/NIC AO • Alaska SAR Facility – ALOS North American Node

North American Ice Service IICWG VIII – Frascati, Italy De Abreu et al. Extra Slides

North American Ice Service IICWG VIII – Frascati, Italy Analysis Objectives De Abreu et al. 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

North American Ice Service IICWG VIII – Frascati, Italy De Abreu et al. Analysis Methodology 1. Pre-launch assessment of L-band SAR based on airborne data sets and backscatter modelling Completed -- L-Band C-Band SAR Scattering Signature of Sea Ice for Operational Applications -- Son Nghiem, JPL, 2007.

North American Ice Service IICWG VIII – Frascati, Italy De Abreu et al. Nghiem, JPL, 2007 L-band modelled and observed backscatter

North American Ice Service IICWG VIII – Frascati, Italy De Abreu et al. Nghiem, JPL, 2007 C-band modelled and observed backscatter