Radar study could help predict dangerous Great Lakes currents
A new Great Lakes study using radar could save swimmers’ lives by enabling the prediction of dangerous currents before they form.
“This is the first application of radar technology [for] actually measuring and detecting rip currents,” said Guy Meadows, director of the Great Lakes Research Center at Michigan Technological University and a researcher on the project.
Rip currents funnel water out toward the lake or sea through a break in a sandbar. They are the leading cause of swimming deaths in the Great Lakes.
The goal of the study is to test how radar can generate data about waves to predict when they form rip currents,, said Ron Kinnunen, a fellow researcher and extension educator for the Michigan Sea Grant, a research, education and outreach agency under the National Oceanic and Atmospheric Administration.
The technology is similar to Doppler radar that helps meteorologists forecast the weather. Both use the Doppler effect, which happens when radio waves sent from an antenna are reflected off moving objects and back to a receiver to provide an object’s motion and direction.
If the frequency of radio waves is unchanging, the object is still. If their frequency is increasing, then the object is moving toward the receiver. If their frequency is decreasing, then it is moving away.
But instead of the atmosphere, the radar is applied to the surf to detect the presence of rip currents, Meadows said.
The research is especially important now, as deaths from rip currents have increased dramatically over the past few years.
“This is really aimed at trying to understand the mechanisms that cause rip currents to occur here on the Great Lakes because the Great Lakes are typically not associated with rip currents, yet we’ve had an enormous number of drownings because of [them],” said Meadows. “It’s a new, emerging issue that we want to bring advanced technology to bear to try to better understand the physics involved.”
One fascinating aspect of the study is the robots that will assist the researchers.
These Autonomous Underwater Vehicles will supplement the radar units by swimming into the region of the currents and confirming the units’ measurements, said Kinnunen.
They will help map both the lake’s bottom topography and actual currents, said Meadows. The actual radio waves are delivered by the radar units.
One such device was recently used to evaluate the water quality around Chicago beaches.
“It looks like a torpedo,” said Meadows. “It’s about six inches in diameter, about six feet long, propeller on the back. You preprogram it and turn it loose and it can swim back and forth doing its mapping for up to about eight hours at a time.”
Once the study is over and researchers better understand how to forecast rip currents, the hope is that radar units could be installed at beaches.Warnings of dangerous currents could appear in the local meteorologist’s weather forecast, Meadows said.
The study is being conducted along two sections of Lake Michigan coast. One is along U.S. 2 in Mackinac County and the other is in the Grand Haven and Holland areas.
Researchers hope to be done by late August or early September.
“Part of our reason for delaying is the beaches have been extremely crowded this year…and it’s hard to run radars and torpedo-like vehicles up and down a bathing beach when it’s full of bathers,” said Meadows.