by Penny Holliday, Principal Scientist
This morning we left the calm of Southampton docks to set out on a new expedition on the Royal Research Ship Discovery: cruise number DY078. Over the course of the next 3 weeks we will collect data from a part of the ocean that we have visited every year since 1975 – a programme named the "Extended Ellett Line" in tribute to David Ellett, the oceanographer who began this work over 40 years ago (pictured below).
Our journey will take us from the inshore waters of Scotland, out into the deep and open North Atlantic ocean to a wild rocky islet called Rockall, and north towards the glaciers and volcanoes of southern Iceland. The aim of DY078 is to measure the temperature, salinity, oxygen and nutrient concentrations of the ocean along a line that runs from Scotland to Rockall to Iceland (which we call the "section"). The repeats of this section tell us how the ocean has changed since 1975, and from that we learn new things about the way the ocean currents work, how and why they change over time, and the implications of those changes for climate and for marine ecosystems.
Over recent years we have been adding to this programme of repeated sections by leaving instruments in the water for a year at a time, attached to very long moorings that are anchored to the seafloor and held upright by buoys. These moorings are part of a relatively new programme called OSNAP that has similar moorings strung out across the whole North Atlantic between Canada, Greenland and Scotland. Together they will tell us for the first time how the vast ocean currents change over time; critical information for understanding the climate system. We will recover the instruments and download their data, and put new ones back in their place.
The people on board the RRS Discovery are a great mix of experienced seagoers and first timers. We hope to share some of our stories about us and our varied work over the coming 3 weeks, and to share our pretty amazing photos of this expedition, so please re-visit this blog to stay in touch with how we are getting on.
Image: David Ellett, the oceanographer who first started making repeated measurements in the deep ocean to the west of Scotland