Anchoring AUVs: Towards a Year-Long Deployment Under Sea Ice

Observations of Antarctic waters are largely limited to the Austral summer as they are largely inaccessible due the prevalence of sea ice for the rest of the year. Measurements in the Amundsen Sea are of particular value due to the significant contribution to sea level rise from the melting of the West Antarctic glaciers that terminate there. Development of new tools to make year round measurements are critical to address this observational gap. Autonomous Underwater Vehicles (AUVs) are a key tool in many areas of ocean observing yet they are typically designed for hours or days of operation. In this paper we describe ongoing work to adapt the Autosub Long Range AUV to enable it to operate for a year under sea ice in the Amundsen Sea. To achieve this we focus on four challenge areas: managing the energy budget by intermittently anchoring the AUV to the seabed to reduce power draw, ensuring navigational accuracy for long term GPS denied operation, managing corrosion and biofouling, and developing the required onboard decision making to enable the AUV to operate during nominal and fault conditions given the constraints of the ice above. The final deployment date is subject to Research Vessel scheduling but is loosely planned for January 2027 to January 2028.