Coastal Oceanography Applications of Digital Image Data from Marine Radar

Abstract

A marine radar attached to a digital image capture system has been adapted for deployment from shore sites. Optimum operating parameters have been identified in relation to the resolution and sampling capabilities of both the radar and the digitization system. Special software enables individual images to be geographically located so that several images can be averaged to reduce speckle and to eliminate features that fluctuate at high frequency. Test deployments at several coastal sites in the south of England confirm that the system is capable of making unique measurements for a variety of oceanographic applications in the coastal zone. The spatial distribution of wave crests approaching the shore can be measured, and by averaging over time, the location of the breaker zone can be established. Although the precise mechanisms for backscatter of grazing incidence radar are not fully understood, it is clear that the radar can also detect the surface signatures of estuarine fronts and wastewater discharge plumes. The interaction between tidal flow and bathymetric features can also be detected by the surface roughness signature. The radar is particularly useful for monitoring the gradual evolution of processes over a tidal cycle.