Super Swell & Snow Petrels
During the night, the seas have picked up, and today we are pleasantly rocking and rolling—so far. The weather/wind reports are calling for seas of around 20 feet for the next day or so. It’s impossible to imagine what that will look and feel like when you’ve never experienced it before. So, I visit the bridge this morning to find out more. We’re allowed on the bridge at any time to watch the action, unless the red light outside it is on—a sign that we must not enter.
The view from the bridge is as fantastic as it is expansive. All we can see in any direction is ocean and sky. Snow petrels glide and swoop, following the ship for the feast it churns up in its wake. Up here, with such a grand view, the waves far below us, it’s easy to enjoy the 8-10 foot swell we’re currently in.
The captain tells me that yes, we’re headed into stronger winds and big seas. When I ask the wave height of the heaviest seas he’s sailed in the Southern Ocean, he says 60 feet. I must look shocked because he adds that bigger waves can be easier: there’s more lag time between the trough and crest of the wave and less rolling from side to side. Everyone gets seasick, the third mate adds, even if it’s not to the point of vomiting. Seasickness asserts its influence most often as fatigue and sleepiness. It’s no wonder when we are living on a moving surface and constantly must engage our muscles to stay stable, not to mention the disorienting movement of the ship. “Expect to sleep a lot over the next couple of days,” says the captain.
Those of us who think we might be prone to seasickness have either put on a seasickness patch—a small sticky circle that sits just behind the ear—or taken seasickness medication. It’s important to begin preventative measures before the boat is underway, otherwise they are nowhere near as effective. The captain advises me to eat a lot, as that will help also. It’s also helpful to stay lower in the boat where there is less rocking and to look at the horizon when possible. A few people suggest that it’s also worse if you think about it, saying it’s best to stay busy and not focus on the feeling.
“It’ll be fun, like a ride,” says Christina, referring to the increasing wave height. “I love the feeling of weightlessness. Just keep your knees loose. I predict you’re going to like it.”
In the afternoon, we have a science team meeting in the conference room. The marine, IT (Internet), and ET (electrical) technicians are also present. Becky explains our goals for the cruise.
We think diatoms record the chemistry of the water in which they are living within their frustules (their glass skeletons). By collecting seawater (containing diatoms and dissolved nutrients, among other things) from various depths, and sediment containing diatom frustules from the ocean floor, as well as growing live diatoms captured from surface waters, we’ll examine how well the nitrogen and silicon isotope signatures of diatoms reflect the composition of the water in which they grow.
Becky presents our schedule for each sampling station. Typically, sampling days will start at 5 am with a survey of the seafloor to find an ideal location to work and follow with a CTD. A CTD is a sensor pack that is lowered to the seafloor, collecting data related to the major properties of the water, including Conductivity, Temperature, and Depth, as well as other measures such as oxygen and fluorescence. The CTD is lowered with a rosette of Niskin bottles to collect water at the same time. After we get the water on board, we move to pumping to collect particles, followed by pumping to examine the trace metal composition of the water. During the afternoon through evening, the megacorer and gravity cores will capture deep-sea sediment until midnight or so.
Once we’ve successfully carried these out, we’ll sail on to our next sampling station. We’ll visit 13 stations in all, as we transect the notoriously rough Antarctic Circumpolar Current (ACC), which churns around the continent of Antarctica. I’m quite intrigued to see how we’ll all work on a constantly moving surface!