Integrated Report on Mechanisms Responsible for Narrow Angle V-Wakes in the Georgia Strait Experiment

摘要

The Georgia Strait Experiment was designed to identify the mechanisms responsible for SAR imaging of narrow angle V-wakes. SAR overflights were coordinated with surface measurements of environmental conditions and of wave height and slope within a ship wake. Narrow V-wakes were observed by and L-band aircraft SAR with incidence angles of 20 - 50 deg, under low ambient wind conditions for all relative orientations between the SAR and ship tracks. These V-lines are a few pixels wide (approx 10 m), several kilometers in length, and approx. 17 db above the background radar backscatter at a distance of 1 km behind the ship. Surface measurements and modeling analysis from this experiment demonstrate that these V-wakes are unrelated to ship-generated internal wave wakes. The qualitative features of L-band V-wakes are consistent with first order Bragg scattering from intermittently generated ship surface waves. This report reviews the theoretical basis and the experimental evidence supporting this mechanism.