Detection of wind fields from PALSAR-2

Abstract

The relationship between ocean wind vectors and L-band normalized radar cross sections (NRCS) is examined to modify the L-band geophysical model function (GMF) using the Phased-Array L-band Synthetic Aperture Radar 2 (PALSAR-2) and scatterometer wind data. The difference between the present study and previous one using the PALSAR is incidence angle range and polarimetry. Since the PALSAR-2 has a function of dual polarized ScanSAR, the sensitivity of L-band HV on wind fields is also examined. Though the HV signal shows wind speed and incidence angle dependencies, they are too noisy to be used for wind detection. Based on more than 20,000 match-ups, the L-band HH NRCS dependence on wind speed, incidence angle, and relative wind direction is modeled for the 0–20 m/s wind speed range. Wind speeds are then inversely estimated from the mutch-ups and compared with the reference winds. The accuracy shows incidence-angle-dependency. The detection at the lowest incidence angles of 25–30 degrees gets the best result, the 0.23 m/s bias and 2.33 m/s root mean square (rms) error.