Let the Science Commence!

What a year for the U.S. AMLR Program.

After more than a month of quarantine for our field camp personnel, an eight-week delay of our shipping container, and a one-week delay of the research vessel's departure for Antarctica, our field season has finally begun.

Whew!

The camp was opened safely and the crew has already begun collecting data on penguinand Antarctic fur sealpopulation dynamics, reproduction, and diet.

The glider deployments weren't quite as smooth as the camp opening.

Our original plan was to deploy two gliders just north of Livingston Island, in an important foraging area for seals and penguins. Our ideal deployment spot was an area 10 miles west of Cape Shirreff, where the water is almost 1,000 feet deep. But, right after the camp was opened, the weather got so bad that the ship's crew was forced to deploy one glider less than two miles north of Cape Shirreff, where the water is just over 200 feet deep and the tidal currents are strong.

Water that's 200 feet deep sounds pretty deep, right? Well, in the world of gliders, ours are HUGE-think 18-wheel trucks when most gliders are pickup trucks-and they were designed to dive deep. Really deep. Over 3,000 feet deep. They don't like shallow water because they're too big to turn fast, and they really don't like strong currents. Our huge gliders dive at about eight inches per second, and they have trouble fighting currents faster than that.

A deep-diving glider trying to maneuver in 200 feet of water in currents traveling almost twice as fast as it can move is like a person trying to swim laps in a puddle on the sidewalk in gale-force wind. It just doesn't work very well.

We were lucky that, although the weather was bad the day we deployed the first glider, the currents were calm and we were able to get the glider into deeper water quickly, before it could get swept onto a beach. But we weren't able to deploy the second glider.

The ship's crew planned to try again the next day to deploy the second glider off Cape Shirreff, but once again, the weather was too bad. Instead, we decided to deploy the glider farther south along the Antarctic Peninsula, in an area important for Antarctic krill that we hadn't studied before.

That deployment was less-than-smooth also, but for different reasons.

I recently wrote about why it's important to ballast-or weight-a glider properly for the water where it will be deployed. If it's too heavy, it will dive, but it will have trouble climbing. If it's too light, it won't be able to dive.

The water where we deployed the second glider wasn't as dense as we anticipated, so the glider was too heavy. Fortunately, before we release a glider into the wild, we do a couple of test dives with a line and buoy attached, just in case anything goes wrong. The glider dove just fine, but couldn't come back up to the surface, so we had to pull it up twice. Once we figured out that the glider was too heavy, the weather was bad again and we couldn't deploy.

Where we intended to deploy the glider AMLR01, and where we actually deployed AMLR01. Credit: Slocum Fleet Mission Control software, Teledyne Webb Research.

The next day, after removing around 100 grams of weight from the glider, it was successfully deployed! Third time's a charm!

Now comes the hard part: piloting gliders for three weeks.

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