Autosub tracks - 2014
Description
Using the same equipment and specification as the 2009 Pine Island Glacier survey, the Autosub3 was deployed from the JR294 research cruise. A total of six missions were planned :
1. A survey of the unsampled bay to the south of the main fast-flowing section of the ice shelf (approximately 30 hours). Although a glaciologically quiet area this appeared to be the deepest basin where the warmest waters within the cavity were likely to be found.
2. An exploration of the inner cavity focussing on the 2009 track to the grounding line (approximately 30 hours). We planned a fairly close approach to the seabed (100 m) to access the warmest waters within the inner cavity.
3. A study of turbulent mixing over the crest of the ridge (approximately 40 hours). This would involve a full 24 hours travelling back and forth along a 10 km track through the front observed over the ridge in 2009.
4. A long track into the inner cavity (approximately 24 hours) aiming to cross the ridge further to the north and study the unsampled north-eastern corner of the cavity.
5. & 6. Two missions beneath Thwaites Glacier, approximately 30 hours each. Within this largely unknown cavity, Autosub would bottom- follow at different altitudes on the way in and out of the cavity. This strategy was a compromise between the need for a wide an observational coverage as possible and the necessity to minimise the risk to Autosub3. Past experience showed the major environmental hazard to be the unknown, potentially rough ice shelf base.
References
2. iSTAR - working in an extreme environment
Field photo
AUTOSUB 3 autonomous underwater vehicle being retrieved after observational missions beneath the floating tongue of Pine Island Glacier. BAS Image collection (2009/2010) , Pierre Dutrieux