Heading Home With a Plate of Data Spaghetti

(Note: thanks for bearing with us for a few days while we fixed a technical difficulty.)

The blog was quiet last week because we were on the Laurence M. Gould, sailing across the Drake Passage back to Punta Arenas, Chile. After spending 31 days at Palmer Station, about half the Project CONVERGE team are on their way home. Back at Palmer, the radar stations and the gliders are still gathering data for us. The krill and penguin teams, plus one stalwart member of the glider team, will remain at Palmer until the Gould’s next visit, on March 11.

Fieldwork is only one part of the scientific method (granted, it’s often the most fun part). “Now the project shifts focus from logistics—how do we collect the data—to how we analyze the data,” Dr. Josh Kohut said. During the last month the scientists have had just enough time to look at trends in the data and decide how to adjust their sampling. There’s a lot of work left to do before they can really understand what the data say about their hypotheses. Click through the slideshow to see some of the ideas they’ll be exploring:

photocrati gallery

chlorophyll data from a gliderAs an example of the ways the scientists will be combining data when they get back, here’s a graph of chlorophyll readings that caught Dr. Oliver’s eye. This was recorded by a glider in early January during a single dive from the surface down to 100 meters (330 feet). To read it, imagine you’re a glider diving from the top of the graph straight down to the bottom. Pretend the green line is your chlorophyll meter—the farther it goes to the right, the more chlorophyll is in the water. The amount of chlorophyll is a fairly good measure of the amount of phytoplankton.

From the graph it’s pretty clear that there’s a small amount of chlorophyll in most of the water, but a huge amount at roughly 7 meters (23 feet) deep. The glider data shows this thin layer over most of the region for most of the month of January, Dr. Oliver said. The depth changes from place to place, as if the phytoplankton sank to a specific level and then stayed there. As Dr. Oliver put it, “There’s a layer of thick green soup under Palmer Station that everybody’s eating.”

Dr. Oliver wonders if this density layer is helping to concentrate phytoplankton in addition to, or possibly even more than, the effect of convergences at the surface. But to know how important this is to the big picture, he needs to add in results from krill surveys and penguin tracks. He also needs to analyze the whole set of glider tracks, not just this single plot from one hour of one day. It’s this sort of painstaking office work that will occupy the scientists during the next stage of the project.

a compilation of all the data types gathered by the CONVERGE team

This is what the scientists have to make sense of now: the grid of tiny arrows represents the radar data; the long colored lines are tracks of gliders and penguins; and the colored dots close to Palmer Station (top center) show the krill surveys.

At the moment, the data the scientists are heading home with is like an enormous pile of spaghetti. The image at left shows a snapshot of the radar data with the tracks of the gliders, the path of the krill team’s echosounders, and the tracks of the tagged penguins laid on top. Each one of those dots represents a separate set of data, like a plate of noodles, that needs to be untangled, straightened out, and then recombined to answer the specific questions the scientists come up with.

They’ll be starting that untangling process this spring. Then they’ll get together in June to plan out the full analyses that, in a year or so, will give them formal answers to the questions they came down here with.

We’ll be back tomorrow with one more post about Palmer Station. Thanks to everyone for following along with us on our long expedition.

 

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