Remote Detection of Ocean Surface Roughness Changes

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.