Performance metrics for oceanographic surveys with autonomous underwater vehicles

The focus of this paper is the development of tools to facilitate the effective use of AUVs to survey small-scale oceanographic processes. A fundamental difficulty in making oceanographic surveys with autonomous underwater vehicles (AUVs) is the coupling of space and time through the AUV survey trajectory. Combined with the finite velocity and battery life of an AUV, this imposes serious constraints on the extent of the survey domain and on the spatial and temporal survey resolutions. In this paper, we develop a quantitative survey error metric which accounts for errors due to both spatial undersampling and temporal evolution of the sample field. The accuracy of the survey error metric is established through surveys of a simulated oceanographic process. Using the physical constraints of the platform, we also develop the "survey envelope" which delineates a region of survey parameter space within which an AUV can sucessfully complete a mission. By combining the survey error metric wit the survey envelope, we create a graphical survey analysis tool which can be used to gain insight into the AUV survey design problem. We demonstrate the application of the survey analysis tool with an examination of the impact of certain survey design and parameters on surveys of a simple oceanographic process.