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GLERL 2001 Milestone Reports
GOAL: SUSTAIN HEALTHY COASTS
OBJECTIVE 2: Promote Clean Coastal Waters to Sustain Living Marine Resources and Ensure Safe Recreation, Healthy Seafood, and Economic Vitality
PM: Number of coastal and Great Lake states provided with improved predictive capabilities and understanding of coastal processes.
Milestone: Complete improvements to the algorithm developed for Great Lakes ice cover classification and mapping using satellite SAR (Synthetic Aperture Radar) data.
Scientist: G. Leshkevich
Purpose: This study was to develop algorithms to classify and map Great Lakes ice cover using satellite SAR (Synthetic Aperture Radar) data. The goal was to collect calibrated polarimetric SAR signatures (C-band) in the field (Lake Superior) to form a library of backscatter signatures for different ice types. This knowledge is important for the development of objective, automated computer interpretation and mapping of Great Lakes ice cover
Efforts: In cooperation with Dr. Son V. Nghiem at the NASA/Jet
Propulsion Laboratory, calibrated polarimetric C-band backscatter signatures
(0-60 degree incidence angles) from different ice types on Lake Superior
were recorded using a C-band scatterometer mounted on a U.S. Coast Guard
icebreaker during February and March 1997. Preliminary analysis of ERS-2
satellite SAR data recorded during the
field experiment has been conducted using the library of signatures collected.
Customers: This study funded through the NOAA Coastal Ocean Program will provide important improvements for processing and interpreting SAR ice data for the National Ice Center (NIC), U.S. Coast Guard, and National Weather Service..
Significance: This was the first attempt to measure polarimetric C-band backscatter signatures from different freshwater ice types in the field to develop a library of signatures (lookup table). This unique data set can be used to machine classify and map Great Lakes ice cover from calibrated satellite C-band SAR data including ERS-2, RADARSAT, and soon to be launched ENVISAT data (Jan. 2002).
Success: Calibrated ERS-2 satellite SAR data recorded at the time of the experiment was analyzed using signatures for a subset of ice types and open water from the library of C-band signatures collected in the field. Most of the ice cover in the two ERS-2 scenes were classified using the subset, however open water was not classified in the scenes. After a more thorough calibration of the ERS-2 scenes (correcting for power loss) and by using signatures at more exact incidence angles, a better classification of the scenes resulted compared to ground truth data collected during the field experiment. Open water was classified after the re-calibration.
Next steps: Owing to the recent development of calibration algorithms for RADARSAT ScanSAR Wide A data, analysis of a RADARSAT scene collected during the field experiment is currently being completed. In addition, a field experiment to collect airborne interferometric C-band and L-band data over Great Lakes ice cover to use in the development of algorithms to map ice thickness using satellite interferometric data is being planned for the upcoming winter (winter 2002).
Last updated: June 10, 2002 mbl