Surveying the underside of an Arctic ice ridge using a man-portable GAVIA AUV deployed through the ice

In April 2007 a man-portable Gavia underwater vehicle was deployed to perform high-resolution bathymetric surveys of the underside of the Arctic ice cap at the SEDNA ice camp in the Beaufort Sea. Deployment and recovery was through a single hole in the steadily drifting ice cap. The vehicle was flown inverted for optimum use of its normally down-facing payload sensors, that included the GeoSwath 500 swath bathymetry sonar providing co-registered high-resolution swath bathymetry and side-scan sonar imagery, and a high-frame rate digital camera simultaneously providing a continuous photographic survey. Navigation was by an inertial navigation system aided by Doppler Velocity log tracking the underside of the steadily drifting ice sheet, thereby referring both vehicle navigation and scientific data to the moving ice cap. The resulting data provided a uniquely detailed rendering of the underside of Arctic pressure ridges, that determine navigability of the future Arctic seaways as the ice cap becomes thinner by global warming.