30 April 2015 Cruise Wrap-up and Results

Journal Entry

Updates

We made it back to Hobart! We still have busy days of packing and unloading before we depart the vessel. We also still have to finish the official cruise report since we got in early and had less time to work on it than expected. The cooks did bring on some fresh fruits and vegetables today. I cannot express how happy I am to see raspberries and strawberries and lettuce.

Cruise Report Overview

This has been a very productive trip and we collected a lot of data. Although we weren’t able to do everything in the original research plan—we weren’t able to take any cores—but that is the nature of field research. You have a detailed plan so you can be flexible. However, the science isn’t over just because the expedition is done! Everyone has been working hard on the ship writing up a cruise report and beginning to analyze the data we’ve collected. The scientists will take the data they’ve collected back to their institutions to further analyze and process it. They can compare the data they’ve collected on this expedition with data from previous expeditions, run statistics, and create models with the data to draw conclusions and explanations about what they’ve observed out here. This can take quite a bit of time, but afterwards they will publish their results to let everyone know what they’ve found and learned.

Here’s a quick run-through of all the work we’ve done on this research cruise.

Course Track

We covered a lot of territory on our expedition. Due to a storm, our course to Antarctica was not very direct (we then ended up running into about a storm a week!). Once we got into the area where we originally planned to do research, we found we had to change our plan due to thick sea ice in some areas. However, we were able to access other areas—four glaciers in the region—and were still able to collect a lot of compelling data.

Course track for the NBP1503 research cruise detailing CTD locations. Courtesy of Frank Nitsche.

CTDs

Over the course of this expedition, we did 42 CTDs along the slope and shelf of the Antarctic continent. Compiling the data from the CTD tells scientists a lot about the water structure here. Below you can see a graph of data from one transect, or line, of CTDs that shows several water masses making up the structure of the ocean in this area.

Compiled data from multiple CTDs along a transect showing a profile of the oxygen, temperature, and salinity of water masses along the continental shelf of East Antarctica. Courtesy of NBP1503 Team.

This plot shows cold, fresher, oxygenated surface water, warmer middle water, and colder saltier deeper water. However, we found some very interesting water features on the Antarctic shelf. We found that in some areas along the Antarctic coast, there is warm water deep on the shelf close to the glaciers, and in other areas there wasn’t. When we say warm water, we mean relatively warm—like 34 or 35F. This is still warm compared to the usual 30F or colder water, and is warm enough to melt glacial ice on the continent. When the scientists get back to their institutions, they’ll further analyze and process the information they’ve collected to understand why this may be, and what impacts it will have on Antarctic glaciers.

Bathymetry and Subbottom

With the multi-beam bathymeter we mapped over 3177 miles of never before mapped area along the Antarctic coastline. We were able to get a lot of fine detail along the continental shelf and slope.

Coverage of multi-beam bathymetry data acquired during NBP1503. Courtesy of Frank Nitsche.

Although some rough data and interpolated maps exist in the area we were researching, you can see the difference in the existing data and the data we obtained on this expedition.

An overlay of ocean bottom multi-beam data collected on this trip on an existing, interpolated map of the area. Courtesy of Frank Nitsche.

We also found some interesting geological features that show past glacial movement, along the ocean floor.

Gullies north of the shelf break and a series of sediment mounds on the continental slope and rise. Courtesy of Frank Nitsche.

The scientists will use this data to help fill in and create more accurate maps of the area. This data can be analyzed to learn more about ice stream dynamics and past ice stream movement and it will also be used in conjunction with the CTD data to learn more about the impact of the warmer ocean water on the glaciers of the area.

Along the same course as the multi-beam, we also used sound (at a different frequency) to map the subbottom. The subbottom system, which works similarly to the multi-beam, is another way to measure depth but it is also capable of characterizing the layers of sediment and rock just below the ocean floor. As we had originally intended to take cores, the subbottom profile was used to help us identify good locations with lots of sediments. Although we ended up not doing any cores, the data collected will help scientists identify features on the ocean floor that we mapped with the multi-beam.

Subbottom data example of a sediment mount along the continental slope. Courtesy of the NBP1503 team.

XBT

We also did 1 XBT to gather data that we used with the multi-beam to help us get a more accurate calculation of how fast the sound from the multi-beam sound is traveling through the water.

UAVs

The UAV team had several successful flights. They were able to ensure their equipment can work well in Antarctic conditions (both weather, and being so close to the magnetic south pole). They also got some great test images of sea ice and are designing a new computer program to analyze floe size.

The R/V Nathaniel B Palmer in Antarctica from a UAV. Credit Dr. Guy Williams, Dr. Alex Fraser, and Ms. Eva Cougnon. Courtesy of USAP and NSF.

Argo Floats

We deployed 10 argo floats that will be collecting data as part of an international network of floats that make real-time oceanographic information available to any country in the world.

…And the Ping Pong Tournament

For those of you that were following along, Team Guyian (Dr. Guy Williams and 3rd Mate Brian) were the winners of the on ship doubles ping pong tournament!