What’s flat, round, and white all over? If you guessed pancakes, you’d be right! But while the pancakes you’re likely thinking of are formed from a combination of flour, water, and oil, the pancakes I’m referring to are formed from the combination of the ocean, cold temperatures, and most importantly, waves. If the ocean is calm, ice forms as smooth sheets like you often see on frozen lakes in winter. If waves are present when the ocean is freezing, the motion of the waves results in sea ice that is flat and round with smooth edges, and so is termed pancake ice. Waves are often present in the Antarctic, and so much of the sea ice that forms begins as pancake ice.
Pancake sea ice in the Arctic Ocean. See the resemblance?
While most people on the PIPERS voyage will be hoping for calm seas, I’ll be keeping my fingers crossed for waves! In the broadest sense, the PIPERS cruise is interested in observing the ice formation process. As most of the ice that forms in this region begins as pancake ice, waves are a crucial part of this story. But you might be wondering: why do waves mean that ice forms as pancakes? We generally understand that the collision of nearby pancakes as they crash together in waves (which you can see in photos both above and below) causes the upturned edges and round shapes that we associate with pancake sea ice. But the exact process isn’t known, which means that we aren’t able to predict when pancake sea ice will form and how big the pancakes will be.
Enter: stereo camera setup. The stereo cameras setup is comprised of two cameras that work much like the two eyes you are using to view read this screen to determine how far away objects are. These two cameras can then be used to measure waves on the ocean surface. (The middle camera is used to correct for the motion of the ship.) As you can see from the images below, we can also pick out pancake sea ice at different locations in the waves, and track it through subsequent images. This will allow us to record the collisions that we expect to be responsible for the formation of pancake sea ice.
Stereo camera setup installed on the rail of the Sikuliaq in the Arctic Ocean. Stereo image pair depicts pancake wave motion during a large wave event.
These pancakes might not taste as good with a pat of butter and swirl of syrup, but understanding when and how pancake sea ice forms is a key part of understanding the future of the sea ice cover. Pancake formation can result in thicker ice pack; ice that forms as pancakes is thicker than sheet ice that forms at the same temperature. However, pancake formation can result in an ice pack that melts out faster come springtime; pack ice that forms from pancakes is less uniform that pack ice that begins as a sheet.
After pancake ice begins to grow, the fun has only just begun. We have many other questions about the relationship of ice and waves in the tumultuous waters of the Ross Sea: how rapidly do the waves from the Southern Ocean get attenuated by the ice in the Ross Sea? Does dissipation of wave energy enhance or suppress ice production in the strong winds of the polynyas? We’ll use a number of techniques to address these questions, including throwing in a bunch of wave buoys such as the SWIFT buoy in the image below.
SWIFT buoy in pancake sea ice in the Beaufort Sea. The SWIFT measures waves, as well as wind speed and direction, air temperature, water temperature and salinity, and mixing due to waves just below the surface.
It looks like we might get “lucky” in the upcoming crossing to Antarctica with waves predicted to be only 5-6 m (16 to 20 feet) most of the time. But don’t worry: this is more than enough to make some serious pancakes. In just a few days, we’ll be having pancakes for breakfast, lunch, and dinner.
Maddie Smith is a PhD student at the University of Washington. If you are interested in following along more with her journey on PIPERS, please visit her blog Maddie At Sea.