January 20, 2011 4:25 PM
by moliver
Penguins, AUV's, Satellites: together at last
Adelie Penguin Rookery on Humble Island
Satellite tagged Adelie Penguin
Penguin swimming tracks near Palmer Station
Ballasting the Glider (Blue Hen)
Is it possible to follow penguins from space to understand where and how they are feeding in Antarctica? Absolutely!..but not without an excellent team from University of Delaware, Rutgers University, Polar Oceans Research Group, and Cal Poly San Luis Obispo. The sequence starts with the "Birders". The "Birders" are from Polar Ocean Research and they have been studying penguins in the West Antarctic Peninsula for years. The "Birders", headed by Bill and Donna Fraser, head out to local rookeries to identify good penguins to tag with satellite transmitters. Finding the right breeding pair is key. The pair should have two chicks with both parents still around. Some chicks only have one parent, probably because one parent was killed by a Leopard Seal. We want to choose one of the parents, because we are pretty certain they will return to their chicks to feed them. This also helps in recovering the transmitter. If the bird does not return, the transmitter comes off during their natural annual molt cycle. Once a penguin is selected, it is gently fitted with a satellite transmitter. Special waterproof tape is used to connect the transmitter to the thick feathers on the back of the penguin. The penguins are remarkably calm during the process. Once the tag is attached, the penguin is released back to its nest. The next part of the sequence is for the birds. The penguins head out to feed on krill and small fish in the area. Their tags relay their position information to ARGOS satellites and we get nightly updates. The Birders pass on their data to me nightly, and I filter and map the penguin tracks. I put them into Google Earth, so we can see where the penguins have been feeding. Then, through the magic of mathematics, we turn their tracks into predicted penguin densities. Based on these densities, we plan our AUV missions to intersect with the feeding penguins (Slocum Electric Gliders and REMUS AUV's). The first priority is to make sure the AUV's are ballasted correctly. This means that they need to be trimmed with weights just right so they travel correctly under the water. We use small balances and scales to get the weight of the vehicle just right, then put them into ballasting tanks to make sure we did it correctly. The vehicles should hold steady just under the surface of the water.
Getting ready for the launch of the "Blue Hen" (M. Oliver and K. Coleman)
Once we have a planned mission, we head out in small zodiacs from the station to a pre-determined point. For the Gliders, we call mission control at Rutgers University (Dave, Chip, John) and let them know a glider will be in the water shortly. Once it is in, control of the glider is accomplished via satellite telephone directly to the glider. The glider calls in and reports data and position to mission control. We can see the data coming in live over the web, and in Google Earth as we navigate the vehicle to where the penguins are feeding. The gliders move by changing their ballast, which allows them to glide up and down in the water while their wings give them forward momentum. They "fly" about 0.5mph for weeks at a time!
Mark Moline with REMUS's
In contrast to the Gliders, the REMUS vehicles are very fast and are designed for shorter, 1 day missions. Daily missions are planned around the penguin foraging locations. The Cal Poly Group (Mark Moline and Ian Robbins) have been launching 2 Remus Vehicles per day to map areas the gliders can't get too. Like the gliders, these vehicles call back via iridium to let us know how they are doing in their mission.
Glider Dances around Adelie Penguin Tracks in a sea of chlorophyll
Finally, we are getting satellite support from my lab at U.D. Erick, Megan and Danielle have been processing temperature and chlorophyll maps in near-real time to support our sampling efforts, as well as AUV operations up and down the West Antarctic Peninsula. Just today, we saw that the penguins in Avian Island (south by a few hundred miles) have been keying off of a chlorophyll front. RU05 was deployed by the L. M. Gould and will be recovered soon. All in all, it is a pretty awesome mission to track these penguins from space and AUV's. We will see how the season develops!
Art Trembanis
No comments:
Post a Comment