Hamilton Reef
06-09-2008, 06:59 PM
On Superior, lighthouse rises to different calling
Scientists hope data collected from atop structure can help with riddle of lake water loss.
TRAVERSE CITY -- For more than a century, the Stannard Rock lighthouse existed for one purpose: warning mariners away from a deadly reef lurking just below the surface of Lake Superior.
Now it has a new mission. Scientists have placed equipment atop the 110-foot-high structure, hoping to determine how much of the giant lake's water is being sucked into the atmosphere.
The scientists are using a technique called eddy covariance, which combines humidity and air velocity data to calculate how fast water vapor rises from the lake surface. It's similar to observing the way smoke wafts upward and outward after candles on a birthday cake are blown out, Spence said.
The gear includes a sonic anemometer, which produces three-dimensional wind measurements, and an analyzer that gauges water vapor in the air at intervals lasting only tenths of a second. Sensors keep track of air and water temperature, solar radiation, relative humidity and wind speed and direction.
It's a complex process, and location is crucial. It can't be too close to land, where conditions can be much different from over open water.
The researchers plan to compile data from Stannard Lighthouse for two years, extrapolating the findings to cover the entire lake by adding information from other sources to the equation.
"We're sort of pushing the limits of the technology," Spence said.
http://detnews.com/apps/pbcs.dll/article?AID=/20080609/METRO/806090366/1409/METRO
Scientists hope data collected from atop structure can help with riddle of lake water loss.
TRAVERSE CITY -- For more than a century, the Stannard Rock lighthouse existed for one purpose: warning mariners away from a deadly reef lurking just below the surface of Lake Superior.
Now it has a new mission. Scientists have placed equipment atop the 110-foot-high structure, hoping to determine how much of the giant lake's water is being sucked into the atmosphere.
The scientists are using a technique called eddy covariance, which combines humidity and air velocity data to calculate how fast water vapor rises from the lake surface. It's similar to observing the way smoke wafts upward and outward after candles on a birthday cake are blown out, Spence said.
The gear includes a sonic anemometer, which produces three-dimensional wind measurements, and an analyzer that gauges water vapor in the air at intervals lasting only tenths of a second. Sensors keep track of air and water temperature, solar radiation, relative humidity and wind speed and direction.
It's a complex process, and location is crucial. It can't be too close to land, where conditions can be much different from over open water.
The researchers plan to compile data from Stannard Lighthouse for two years, extrapolating the findings to cover the entire lake by adding information from other sources to the equation.
"We're sort of pushing the limits of the technology," Spence said.
http://detnews.com/apps/pbcs.dll/article?AID=/20080609/METRO/806090366/1409/METRO