Final Stop: Antarctica’s Ross Ice Shelf
By Julian Spergel
We have embarked! Our third Antarctic field season is underway, putting us only 18 flights away from completing our mission to investigate the Ross Ice Shelf, the largest ice shelf in Antarctica. The Rosetta-Ice Project is focused on developing a more complete understanding of the Ross Ice Shelf, the history of how it formed, the factors driving its current condition, and what might control its future stability.
It is this writer’s first Antarctic field season, although traveling to Antarctica has been a life dream of mine since high school. I came to my obsession in an unusual way. In the summer of 2011, a heat wave knocked out the air conditioning units in my town. Sweltering, I took what little refuge there could be had in the public library. I had read somewhere that reading about cold places could cool you down, so for the next few weeks I pored over every account of polar exploration I could get my hands on. I was hooked, and especially hooked on Antarctica. It represented to me a place that remained mysterious and extreme, and whose challenging exploration by scientists represented the pinnacle of human ingenuity and international collaboration. I feel honored to be included in this field season, and to be documenting our findings and experiences for readers to learn from and enjoy. It is exhilarating to be on my way to achieving a personal goal of mine. Though when I pictured myself as an Antarctic explorer as a teenager, I thought I would be taller!
To more thoroughly introduce the Rosetta-Ice project, it is a multi-year collaboration between Lamont-Doherty Earth Observatory, Scripps Institute of Oceanography, Colorado College, and Earth & Space Research, with funding from the National Science Foundation and critical support from the New York Air National Guard. Our goal is to complete a high-resolution survey of the Ross Ice Shelf in West Antarctica.
The Ross Ice Shelf is a floating ice shelf, roughly the size of Texas or France, that extends from the Trans-Antarctic Mountains into the Ross Sea, the portion of the Southern Ocean that faces New Zealand. Part of the ice shelf’s perimeter is grounded, a term that means frozen all the way down and connected at the base to the seafloor below. The rest of the shelf extends out floating as a thick apron of ice with about 10 percent of it visible above the ocean’s surface; the rest floats below the waterline. The ice shelf is up to 4,000 feet thick in its interior, and its margin with the sea is nine hundred feet thick in places. A large percentage of the surrounding ice streams in the Trans-Antarctic Mountains and West Antarctic Ice Sheet flow into the Ross Ice Shelf. As a result, the friction of the grounded portions affects the rate at which the ‘upstream’ ice flows and loses its mass through iceberg calving.
Rosetta-Ice is a detailed aerogeophysical survey, a series of survey flights collected using LC130s, rugged military cargo planes that fly equipment and support in the polar regions. The planes carries a variety of remote-sensing instrumentation inside an attached structure called IcePod, and flies a tight grid of observation tracts collecting data. The ultimate result will be a map of the Ross Ice Shelf with a spatial resolution of 10km (6mi). This will give us a comprehensive look into the ice shelf’s surface elevation, its internal glacial layers, its thickness, the ocean circulation beneath it, and the morphology of the bed beneath.
The research questions that the project seeks to answer concerns the ice shelf’s past and future. We want to understand how the ice shelf formed, and we are thus studying the internal structures within the ice and the bathymetry and geology of the bed underneath. Looking from the past to the future, we are interested in the stability of the floating ice. For this question, we are studying the circulation of ocean water underneath the ice, how the ocean interacts with the ice through melting, and where the ice shelf may be resting on the underlying bed. Each one of our instruments’ data gives us a piece of the answers. The Rosetta Stone, our project’s namesake, was inscribed with a message in multiple languages that could only be completely understood by comparing the three translations and interpreting them together. Likewise, we are interpreting our data from ice-penetrating radar, visual and infrared imagery, magnetic readings, and gravimeter information together to produce a complete picture of the Ross Ice Shelf’s dynamics.
In this coming week, we will be settling into McMurdo Station, the largest of Antarctica’s research stations, and setting up and calibrating our instruments so that we can begin this year’s flights as soon as we can. For more information about previous years’ work, please take a look at previous blog entries in the archives of this blog.
Julian Spergel is a graduate student at Columbia’s Lamont-Doherty Earth Observatory and the department of Earth and Environmental Sciences. He’ll be blogging from Antarctica for this final season of the project. You can follow along with his posts, and learn more about previous years’ research, here.
For more on this project, please visit the project website: http://www.ldeo.columbia.edu/res/pi/rosetta/