We are just about 6 nautical miles from the edge of the Totten ice band and should be able to break through the sea ice into some ice-free water adjacent to the coast by this evening. Our watch shifts now demand a higher level of attention because we are in un-chartered waters; there is no pre-existing data from this area. Every seafloor feature that shows up on the screen on the Knudsen bathymetric profiler has never been seen before. NBP14-02 will be the first cruise to survey the seafloor and collect geological and physical measurements of the sediment and ocean currents.
Now, all planning is in overdrive. At the transition between shifts, there is usually a PI meeting at the navigation table or in the Chief Scientist’s room. These meetings include deciding which sites to hit first, which group will run their instruments and in what order. As we steam toward Totten Glacier, the researchers running the seismic instruments are planning their lines (the distance between two waypoints on which they will make their measurements).
These images are very important because they will be high-resolution images of the ocean bottom and the sub-bottom down to about 400 m. That is tens of millions of years of a sediment record in one picture. The seismic images show the various layers and points of contact between geologic periods. For example, we may be able to see the boundary between the Eocene and Oligocene.
The physical oceanographers will run their CTDs (Conductivity Temperature Depth profilers) soon after the seismic runs to map the deep currents sinking and upwelling along the shelf and provide information on salinity, temperature, and oxygen content, among other parameters. The data that the physical oceanographers will enable us to understand the role of deep-water masses and ocean temperatures in the evolution of marine-based glaciers and ice shelves. For general knowledge, a marine based glacier is one whose grounding line is below sea level.
In addition to the above-mentioned measurements, the marine geologists will be deploying cores to collect a sedimentary record of the shelf. Some of the cores may be up to 24 meters long depending on the sub-bottom profile that we image in the lab. This profile is key to finding a sequence of sediments that the PIs believe will tell a complete story. We will use those records to reconstruct and understand the evolution of Totten Glacier: how it moved, when it moved, how far it moved, etc.
All the disciplines work together. Without seismic, we wouldn’t know where to core and the physical oceanographers wouldn’t be able to account for bathymetry when mapping currents. Without physical oceanographers, the marine geologists wouldn’t know which currents upwell onto the shelf and come into contact with the ice shelves. And without marine geologists, we wouldn’t be able to confirm the layers on the seismic image. I feel like any data we gather will be good data since it’s all new. We have already seen some new bottom features and I am anxious to see more.
On a side note: I saw my very first emperor penguin today. Check that off the list.