Antarctic voyage: the Mertz Polynya

By Guest Author 31/01/2013

Ever wondered what it is really like to be working on a ship off Antarctica?

Dr Helen Bostock, marine geologist at NIWA, writes:

On the 2nd February I will be part of a team of 22 Australian, French and New Zealand, scientists departing Wellington on board NIWA’s R.V. Tangaroa.

The science team is made up of oceanographers and geologists, and we will be heading out on a 42-day voyage to the Mertz Polynya region of Antarctica.

Credit: Peter Marriot, NIWA from 2008 voyage to the Ross Sea as part of the International Polar Year

In these blog posts I will discuss the planning, preparation and training required for this kind of voyage; everyday life at sea; how and why we are doing the science; any wildlife that come across; the experience of a large Southern Ocean storm; the frustrations of being stuck on a 70 m boat for 6 weeks; and any other mishaps or unexpected events that we experience during the voyage….

Why study the Mertz Polynya?

Back in February 2010 the tongue of the Mertz Glacier broke off after being rammed by a huge iceberg. The Mertz Polynya is one of three areas around Antarctica where the deep waters of the ocean are formed. The so-called “Antarctic bottom waters” are created during the formation of sea ice, which leaves behind very salty, dense water. This salty water sinks to the bottom and flows over the edge of the continental shelf, like an overflowing dam, to the bottom of the Southern Ocean.

So one of the main aims of this voyage is to understand how changes in the Mertz Polynya, caused by the break off of the glacier tongue, will affect the formation of Antarctic bottom water and the flow in to the deep ocean, and the potential global implications of these changes.

The voyage will also be sampling seafloor sediments and taking underwater video to see what lived under the Mertz Glacier Tongue before it broke away. Sediment cores may also provide clues as to how often the glacier tongue has broken off in the past.

The transit to the Mertz Polynya from Wellington will take over a week. But we won’t be bored. We will be collecting lots of samples along the way as we cross the Southern Ocean.

Map of NIWA’s R. V Tangaroa path to the Mertz Polynya area, Antarctica. Credit: NIWA

We will be continuously sampling the surface waters and the air for the CO2 content. We will be towing a “continuous plankton recorder” behind the ship, which collects and preserves plankton. And we will also be collecting a couple of sediment cores and deploying some Argo floats, which measure the temperature and salinity of the ocean. (All of these will be explained in more detail in future blogs.)

These observations and samples will add to the ongoing Subantarctic and Southern Ocean research programmes in New Zealand, Australia and New Zealand. This research is funded by Australian Antarctic Climate and Ecosystem Cooperative Research Centre, L’ocean, France, and NIWA government funded core research, New Zealand.

Follow us on our expedition and experience the excitement, trials and tribulations of marine scientists working at sea!