TAN2502 voyage update – 21 February 2025

Our trip north was uneventful, if a little foggy and swelly. Happily, the Southern Ocean conditions were calm enough that we could even stop and take a CTD profile to the seabed in over 4.5 km of water.  As well as this, en route we measured ocean surface and atmospheric data plus our trusty Continuous Plankton Recorder, all the way back home.

assurance and quality control. While a good number of papers and datasets will come out of this single voyage, the true power is in the intertwined value when the data add to the growing pool of information about the region.

This collective wisdom is growing because the area is important to a range of stakeholders. One way we can maximise this value is through the Southern Ocean Observing System (SOOS) – an international initiative that seeks to develop and share data from around Antarctica. This powerful focal point for collective science is required if we are going to have informed responses to the growing climate challenges.

It is fair to say that the set of shared experiences for everyone onboard will also prove invaluable in the future for collaboration and wider understanding of science.

As we come into port, I can finally own up that probably the most remarkable thing about the entire trip – other than the people, the science and the views – was the weather. Given that the ship is in very good order, our ability to work at such high latitudes is almost entirely governed by the wind, waves, and the cold. As it was, we won something like three lotteries in a row. I estimate we lost about two hours due to fog arriving at just the wrong time for a particular kind of sampling activity.  

Alina Madita Wieczorek / NIWA

For every other Tangaroa Ross Sea voyage you would have added – “and sea ice” to the list of challenges.  While it did affect some of our work, it was only a few days where we found our sampling needed to adapt to drifting patches of ice. This was in part made possible thanks to improved data and models (with interpretation from Evan Solly the ice pilot), and the ability to easily access them via a decent internet link. However, it was also due the stark reduction in sea ice in the region. Sure, it might prove that it was “just a low ice year”, but there really wasn’t much around and all the evidence points to this continuing.

This need to understand a system under pressure is why this work is supported. The sea days are funded by MBIE’s Tangaroa Reference Group. We acknowledge the continued support from the Antarctic Science Platform through the efforts of Professors Nancy Bertler and Ian Hawes with assistance from Mel Climo and Anne-Marie Rowe.  NIWA provided substantial funding through its SSIF Strategic Voyage Fund and CAPEX equipment funding programme - with thanks to Drs Mike Williams and Joshu Mountjoy.

Scientifically, we have a whole cohort of colleagues working behind the scenes - Drs. Vonda Cummings, Nathan Kenny, Holly Winton, Kathy Gunn, Phil Sutton, Assoc. Prof. Melissa Bowen, Prof. Jan Strugnell, Prof. Chriz Zappa, and Assoc. Prof. Stefano Schiaparelli.  Then we have the amazing researchers on board – Prof. Miles Lamare, Drs. Ira Cooke, Nicole Hill, Alina Madita Wieczorek, Svenja Halfter, Gert-Jan Jeunen, Hugh Carter - with additional support from Marco Grillo, Emma Downer and Fiona Schultz.

Thanks go to the ship’s Master Mapu Jr Tapua’i, and the bridge team Ian, Marissa and Ruth (Ninja), for running a fantastic voyage. Everyone aboard played a part in the success – the engineers Rob, Petro and Ragin, and the galley/steward team - Steve, Grant and Jo.  And a special thanks to the deck teams who were out there in all Antarctica’s weather, with winches, nets and cables – Glen, Shane, Bruce, Jordan, Erica and Callum. The ice pilot, Evan Solly, helped navigate the challenging seas and the ship’s Doctor Dr Jenny Visser was a fount of knowledge, doing far more than only looking after our physical well-being.  NIWA Vessels’ Wellington-based team – Simon Wadsworth, Karen Keddy, Sol Fergus, Ross Mitchell, as well as Dave, Brian and many others, got us off the wharf – and will be there to greet us.

Alina Madita Wieczorek / NIWA

Denise and I would like to emphasise that the success of the science was made possible by a combination of the skilled, experienced people on shore and on the ship. The complexity of this endeavour means you can’t just turn up and expect things to work – it requires trained professionals with a can-do attitude. Dr Jasmin McInerney, Nick Eton, Dr Pame Olmedo-Rojas, Jacob Hall, Henk van Rossem and Alicia Maurice on board and Sadie Mills, Dr Stacey Deppler, and Andrew Marriner back at the NIWA Wellington laboratories, were the real secret to succeeding at 76°S.

In addition, if people don't know about the science and the world about them, then the impact of all this effort falls short. A huge thanks for the science communication effort goes to the indefatigable Ryan Willoughby and his colleagues at NIWA, Antarctica NZ and other institutes around the world.  With WhatsApp being a key piece of communication around the ship, Ryan was in on the chat from the first to last with advice, requests, encouragement, suggestions etc.

I’ll finish up this log by describing our last CTD profile of the entire voyage – well north of Antarctica and the Polar Front. I’d dragged myself out of my bunk for the final 5 am profile. Denise was already hard at work in the hydro-lab and with great satisfaction, pointed to the data screen for the CTD as it neatly traced out a text-book example of Antarctic Bottom Water silently flowing four kilometres beneath us - working its way around the planet. This layer of cold, salty, oxygenated water is an essential part of how our planet  works. Despite being two thousand kilometres from the likely formation point where we’d sampled only a few weeks previously - here was clear evidence of Antarctica’s reach, as the water mass headed north to Aotearoa and beyond – and it is changing.

Mā te wā

Craig Stevens & Denise Fernandez

Hana Ishii / Victoria University of Wellington