In the winter, the entire lake is freezing cold. In the summer, the water warms up a bit. (Those might be the two most obvious sentences you’ll read today.)
But in the spring, as the sunshine starts making the water temperatures in Lake Ontario more bearable, the water by the shore heats up much more quickly than that in the lake’s deeper center. The temporary temperature disparity impacts a variety of the lake’s systems, such as pollution levels and algae prevalence, as much of what enters the lake during this season gets stuck in the warm water by the shore.
On Friday morning, a team of specialists launched a robotic torpedo-shaped device — called a autonomous underwater vehicle (AUV) — into Lake Ontario, where it spent hours measuring temperature and ion levels throughout an area near Ontario Beach Park.
“It’s really important that we understand how it works, because right now, we’re sort of operating under that assumption that once (river water) gets to the lake, it’s a big, giant bathtub and everything mixes equally,” said Greg Boyer, director of the Great Lakes Research Consortium, a network of agencies studying the lakes. “If that’s not true, we need to rethink some of our basic assumptions on how things go into the lake and where things end up.”
The temperature difference creates a wall of sorts — scientists call it a thermal barrier — whereby the colder, denser water in the lake’s center blocks particles from the warm water from entering. As a result, the water in the middle of the lake is far less polluted than the water by the shore, Boyer said.
Since Wednesday, Boyer and his team have been sending the $140,000 AUV out into the lake to measure where, exactly, the thermal barrier is. In addition to the reading they took in the water near Ontario Beach Park, they’ve also taken readings in areas near Sodus and Oswego. On Saturday, they’ll take a final reading in an area near Orleans County before comparing the data to satellite imaging of the lake.
The AUV is also measuring ion levels so Boyer and his team can determine in which direction the water from the Genesee River flows after it enters the lake. Once they compile their findings, they can make recommendations as to whether certain steps should be taken in the spring to ensure that the lake systems aren’t as badly impacted by the annual arrival of the thermal barrier.
Michael Johnson, who teaches oceanography at Monroe CommunityCollege, attended Friday’s launch so he could share the experience with students.
“The Great Lakes share a lot of qualities with the ocean,” he said.
The research is being conducted as part of the Cooperative Science and Monitoring Initiative, a collaboration between the United States and Canada. The initiative collects data on the Great Lakes every year, rotating which lake is surveyed each year.