Ice in Motion
From calm to washing machine
Our whole world is about to get thrown about.
For the last 8 days, we have been pushing through new sea ice forming rapidly along the northern coast of Alaska. We have spent a bit of that time along the shore but for much of it we have been 30 or 40 or 70 miles north of the coast, deep in the freshly frozen Beaufort Sea. Swell does not reach this far into the ice so the boat has been perfectly steady, though chunks of ice sliding down the side of the hull sometimes sound like a freight train.
It feels a bit counterintuitive to hang out far from the coast where there are a no waves on an expedition about the impact of waves on coastal ice... But there is a good reason. Every day, Jim and the team analyze the wind, wave and ice forecasts to determine the best plan for the coming days to maximize everyone’s time on the ship. The weather has been very mild over the western arctic this week, with winds less than 15 knots and no big storms. This means very little wave activity along the shore. The biology team, onboard to catch and study arctic cod, have taken advantage of this calm time to fish with their big under ice trawl net. It’s been perfect weather for them.
But soon the switch flips.
There is a big fat low pressure system developing south of us right now that is going to make it much harder to fish with a big heavy net, and much more exciting for people interested in big waves. After a last fishing stop tonight, we are going to leave the protection of the sea ice for an area of the coast that is just starting to ice up to watch the storm roll by. Our intended vantage point is near the site of our first mooring deployment. This way, we will be able to capture the event three different ways: by direct observation, castings off the ship (with the CTD and LISST and SASSY), and also with the anchored moorings.
The forecast models play a huge role in what we do each day on the ship. Throughout the day and always at the nightly science meeting, we look at what the models predict will happen with the wind, waves and ice in the next few days. Since it’s such an important piece of this expedition, I wanted to bring you in to this forecast analyzing stage. Here are some of the charts we have been watching for this next stage of the journey.
First, here is the wave forecast for November 21st, when the storm should peak (where we are). The little green ship is our location now. Icy Cape is where we are headed. The arrows show the direction and the color shows the height of the waves.
Next, here is the ice concentration forecast for the same day in the same part of the world. You can see our red track and how we have primarily been in the purple stuff recently, which is 100% ice coverage.
Now, here is what Jim is zooming in on every day. This is a close up of icy cape with both the wave and the ice forecasts for today (20th), and tomorrow (21st) and the next day (22nd) at 12z (12z is shorthand for 12:00 zulu time, also called UTC universal coordinated time or GMT Greenwich mean time, which is 15:00 3:00pm local). I made these three images into a little gif so you can see the changes easier.
Those little green triangles mark the moorings we deployed at the beginning of the trip (when there was no ice at all). See how the shore-fast ice is expected to grow each day, covering the moorings? These are exactly the conditions that will help Jim and his team better understand how these big storms are impacting the ice that is trying to form along the coast.
Or maybe it won’t happen like that at all. Maybe the waves impede the sea ice from growing and knock back the ice that’s already there. Maybe the ice grows faster and protects the coast (and the ship) from the waves. Maybe the storm doesn’t materialize, or gets much bigger than expected. These are predictions. They are incredibly useful, but they are still guesses based on a complicated range of variables input by a human. And there are so many variables.
But it is this situation – a group of multidisciplinary scientists enduring a big storm in the arctic winter together – that makes these forecasts more accurate. Maybe this very storm event will move the needle just a very little bit towards better modeling of future arctic storms and their impact on the coast. Just maybe.
And so. We are leaving the world of calm and steady sea ice for the washing machine of 3-4-meter (9-12 foot) storm waves. Everyone has become quite complacent about the position and security of phones and coffee cups and toolboxes on this still and steady ship. That all changes soon; it’s time to batten down the computers, slap on a scopolamine patch, and hang on tight!
Words by Becca Guillote
Photo by John Guillote
Forecast images provided by National Ice Center and NOAA