The directional factor of sea spectra is an important oceanographic quantity which has been measured infrequently by a limited number of techniques. Here I report the use of a large-phased antenna array transmitting at 1.98, 3.84, and 5.80 MHz for measuring the directional factor from the observed first-order surface-wave sea echoes (i.e., those due to Bragg resonance) measured simultaneously at many azimuths through rapid, digital control of beam direction. This measurement process compares with the extraction of directional factors from second-order radar cross sections in that both techniques rely on the statistical quality of observations and the stability of integral inversion algorithms employed. Preliminary observations show that, in principle, this new technique can be used to measure the directional factor automatically, including dominant sea direction and angular spread with high resolution (±2°) in near-real time. The strategy required to achieve high accuracy is outlined.
If you can't find a tool you're looking for, please click the link at the top of the page to "Go to old article view". Alternatively, view our Knowledge Base articles for additional help. Your feedback is important to us, so please let us know if you have comments or ideas for improvement.