Synoptic Mapping of Coastal Oceanography Using Acoustic Tomography and Autonomous Underwater Vehicles

Abstract

AUV technology provides a valuable addition to the traditional oceanographic platforms by providing a sensor suite which is rapidly and adaptively relocatable complementing the traditional Eulerian and Lagrangian measurements provided by fixed moorings and floats and drifters, respectively. However, the full potential provided by this new technology is just beginning to emerge. For example, AUV-s may be used as cost-effective mobile source platforms for ocean acoustic tomography-networks. Provided the tomographic inversion can be performed in real time, the oceanographic field estimates can subsequently be used to relocate the AUV resources to areas with high variability or uncertainty to perform direct point measurements. This new Acoustically Focused Oceanographic Sampling (AFOS) concept optimally combines the synoptic volumetric coverage of the acoustic tomography and the spatial and temporal resolution provided by the AUVs. The basic components of AFOS, including new real-time tomographic inversion techniques have recently been demonstrated in connection with the Haro Strait Frontal Mapping experiment. However, the full potential of the combined use of AUVs and acoustic tomography is currently being explored within the context of general coastal ocean forecasting systems where the observational capabilities are directly coupled with oceanographic modeling through data assimilation. This paper describes the progress made so far and discusses the future potential of the combined use of underwater vehicle technology and acoustical oceanography.