Remote Detection of Ocean Surface Roughness Changes

Detection of weak oceanic currents by remote sensing means is an important task for many applications of significance to the Navy and the society at large. A promising way to remotely detect the currents is through variations of backscattering strength of electromagnetic waves scattered from ocean surface roughness modulated by the currents. In Phase 1 of this STTR project we demonstrated that, despite natural variability of sea surface roughness, large-scale ocean surface currents as weak as a few cm/sec can be detected with existing orbiting scatterometers. During Phase II we propose to develop a model of ocean surface roughness modulation due to interaction of surface waves with subsurface currents and turbulent wind; to demonstrate the feasibility of detection of subtle variations of ocean surface roughness by identifying signatures of natural phenomena, such as tsunamis and surface manifestations of bottom topography, in available satellite imagery; to verify the model through a quantitative comparison of predicted and observed signatures of natural phenomena; to design algorithms for detection of underwater physical processes in microwave imagery of the ocean surface; and to determine optimal parameters of the airborne/spaceborne microwave sensors. In case of positive results of Phase II efforts, specialized microwave sensors and systems will be designed during Phase III for robust detection of tsunamis, bathymetric features, and subsurface mines from airborne and/or orbiting platforms.