SBIR-STTR Award

Detection of weak oceanic currents by remote sensing means is an important task for many applications. Recent destructive Sumatra tsunami (2004) demonstrated a key role of the tsunami monitoring and early warning system for preventing numerous human losses and decreasing property damage. Complexity of the problem is explained by very weak current needed to be detected. Nevertheless there are some observations (tsunami shadow) and theoretical arguments indicating that even such small oceanic currents can result in measurable variations of the sea surface roughness. During Phase I we propose to conduct research directed to the development of the theory of roughness modulation due to interaction of surface currents with a turbulent wind and verification of theoretical prediction by studying available microwave radar/radiometric satellite data. Comparison of the satellite observation collocated in space and time with tsunami wave with theoretical modulation of surface roughness and resulting radar/radiometric signal will answer the question of detectability of weak current. In case of positive result of Phase I, the efforts of Phase I optional part and Phase II will be directed toward study of the effect of various environmental parameters on the signal strength, development of the robust detection algorithm, and optimal parameters of the airborne/spaceborne systems.

Benefits:
The proposed research will result in a sensor system and algorithm capable of real time detection of weak current disturbances from aircraft or/and satellites. Such a system would be of great value to the US Government for national security purposes and for warning and emergency management. Specific applications may include tsunami warning, bottom topography characterization in denied areas, and subsurface mine detection. A global, satellite-based system for early tsunami detection will be of exceptional societal value for this and other nations. Through early warning with a low probability of a false alarm, it will help to save lives and minimize economic impact in tsunami-affected areas

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.

Keywords:
Electromagnetic Scattering; Oceanic Technology; Radar Scattering; Maritime Surveillance; Tsunami; Ai