The following post was written on March 23, 2011 by LT George Suh and LT Brandon Schmidt, students at the Naval Postgraduate School in Monterey, CA who have been at APLIS conducting their thesis research. They will be leaving tomorrow after completing nine days of field science. This is the 17th post in a series about ICEX 2011, an Arctic Submarine Laboratory exercise.
Our study focused on the effect of under-ice topography on mixing between layers of seawater in the upper 100 feet of the ocean. To do this, we set up a science hut adjacent to Mt Rainier which extended beneath the water for about 40 feet.
The turbulence and wakes generated in the vicinity of these large underwater features may be a major physical force causing mixing in the shallow ocean. Ice keels may also be responsible for driving fresh water near the surface deeper into the ocean during peak melting season.
We deployed a pair of flux packages on the “downstream” side of the Mount Rainer keel that continuously recorded temperature, conductivity, and water velocity in all three dimensions. These recordings will be used to directly estimate the vertical movement of heat, and salt.
A specially designed sonar was deployed at four sites around Mount Rainer to provide high-resolution measurements of the under-ice geography. This resulting map of the ice keel, along with the data collected about the ice movement, will allow us to directly relate the size and shape of the keel to the vertical movements we calculated.
With the collected this data, we will be able to determine if large ice keels contribute to the turbulent mixing of the Arctic Ocean mixed layer. If this is true, we will be able to quantify the ice keels’ effect on turbulent mixing.