Sea Ice Detection by an Unsupervised Method Using Ku- and Ka-Band Radar Data at Low Incidence Angles: First Results

Abstract

This paper presents the first results of sea ice detection using the data of Ka- and Ku-band radars at low incidence angles. A classification method based on an unsupervised K-means approach is applied to the arrays of the data for the Arctic and Antarctic regions. Comparison with Advanced Microwave Scanning Radiometer 2 (AMSR-2) data was performed, and the dependence of classification performance was evaluated for incidence angles from 0° to 18.15°. This paper evaluates the classification accuracy of sea ice detection based on Ku-band, Ka-band, and their combination. Preliminary results indicate that the classification based solely on Ku-band data achieves the best performance.

Sea Ice Detection Method Using the Dependence of the Radar Cross-Section on the Incidence Angle

“…The performance of the algorithm is good, F-score = 0.93. While the unsupervised method for ice detection in [7] performs worse for this part of the swath (F-score < 0.9). Furthermore, the two approaches can be combined.…”

“…The advantage of the approach is that no precise calibration of the radar is required according to Equation (A8), unlike the methods based on the value of NRCS [6,7]. In the present work, unsupervised clustering was applied.…”

“…This part of the swath is located between grey lines in Figure 3. The part of the swath is confined in such a way as to study the performance of sea ice detection in the area where clustering based on NRCS value from [7] exhibits weak results. Another reason is the limitation of resolution element size along the scanning direction.…”

“…Sea ice detection at low incidence angles is a new and challenging task for remote sensing society. Several works were devoted to sea ice detection using normalized radar cross-section (NRCS) value measured by Sea Wave Investigation and Measurement (SWIM) radar onboard Chinese-French Oceanography Satellite (CFOSAT) and DPR [5][6][7]. SWIM is the Ku-band radar that has beams with incidence angles from 0 • to 10 • .…”

“…The method based on the Bayesian approach, presented in [6], using SWIM radar data on NRCS, revealed good accuracy for incidence angles below 6 degrees. At the same time, a simple classification method based on unsupervised clustering has shown good performance at 4-18 degrees [7]. The problems of sea ice detection using only the data on NRCS for unsupervised clustering occur at incidence angles below 3 • .…”