SIPEX II AUV MERTZ GLACIER CALVING SEAL OCEANOGRAPHY Update from Guy Williams AUV/Sea Ice Specialist Sea Ice Program Cryosphere

SIPEX II AUV Major setback after loss of collaboration with Memorial University and long-range AUV capability for Cryosat-II Calibration/Validation Major comeback with new collaboration with WHOI ‘SeaBed’ vehicle for floe-scale measurements of ice draft during SIPEX-II Collaborative links with UK ICEBELL mission in the Weddell/Bellingshausen Sea in Nov Better integration with other Ice Station projects Floe scale survey (500 x 500 m) 230 kHz multibeam sonar CTD + ADCP Hyper spectral radiometer 4 man team ~$250—300K Integrated with surface measurements and ROV program

Important collaborative links with UK ICEBELL mission in the Weddell/Bellingshausen Sea in Nov Ice thickness maps from 4 unique ice stations Wilkinson et al., Williams (in prep)

Timeline April - Visit to Scottish Association of Marine Science (SAMS), UK, to establish collaboration with the ICEBELL project. May - Visit to Hobart by Hanumant Singh (WHOI) to establish AUV contract for SIPEX-II. Meetings with AAD operations and Aurora Australis crew July - Visit to WHOI, USA, to work with AUV team and ICEBELL project leader on AUV operations for SIPEX and the processing of AUV data from the ICEBELL project. September - Visit to Hawaii, USA for pre-cruise mobilisation experience with the SEABED vehicle. Ongoing processing and analysis of ICEBELL data with SAMS and WHOI for co-authorship on upcoming publications from the UK groups.

Impacts of the Mertz Glacier Calving Ocean-Ice Modelling Kusahara, Hasumi and Williams, Nature Comm Sea ice via Satellite Analyses Tamura, Williams, Fraser and Ohshima (in review Nature Geoscience) 23% reduction in modelled dense shelf water export 27-36% decrease in sea ice production Greater than 0.05 decrease in salinity, equiv. to last 50 years of long-term freshening Contribution to observed changes in oceanography in Rintoul et al., (in prep)

Seals as Polar Ocean Observers in the Prydz Bay/Amery Ice Shelf and Cape Darnley regions Over 15,000 new CTD profiles from elephants seals deployed from Davis Station and Kerguelen Island Amazing new observations of high salinity shelf water and dense shelf water overflows relevant to Cape Darnley/Prydz Bay Antarctic Bottom Water. Sea ice growth rate estimates for the McKenzie Bay and Barrier polynyas Unique summer-fall-winter observations on the continental shelf, across the Amery Ice Shelf and across the southern ocean. 1 st author manuscripts near submission for GRL- style journal and the PLoS-ONE Special volume on ‘Trends and Change’ resulting from the Australia- Japan Antarctic Biology workshop in Feb with Hindell, Field, Roquet, Tamura and Herraiz-Borreguero