|Central and Northern California Ocean Observing System|
In April 2007, the Naval Postgraduate School installed a radar near the beach in Sand City, not far from the location of the Sand City camera tower. The radar has several qualities that make it a useful supplement to video for nearshore monitoring. Its range extends nearly to the horizon, far beyond that of the cameras' rectified images. Unlike video, it functions equally well at night as in the daytime. NPS is currently testing the radar's capacity to detect processes that are not visible to the cameras, including rip current pulsations.
The figure below summarizes recent radar data. In the two images on the
right side, the offshore direction is approximately downward, with the radar
located at the center of each plot.
Wave breaking near the shoreline will appear
as a brighter streak in both the single and the summed images.
Rip channels, when visible, show up
as semi-periodic, darker interruptions of the breaking
in the summed image on the bottom right, comparable to those seen in
rectified images from the
video cameras at the same site. (click image to enlarge). Directional
spectra are plotted for different wave periods in the
twelve panels on the upper left. Here, the horizontal axis corresponds
to the alongshore
and the vertical axis to the offshore direction (corresponding to the orientation of the
single and summed images). The plots generally indicate that the peak wave
energy (red areas) is approaching the shoreline from slightly to the south
of shore normal, in agreement with concurrent
CDIP model predictions and ADCP measurements.