Using Sonar To Measure Ice Thickness

CLEVELAND (AP) – Flanked by wide-eyed colleagues, Lorry Wagner holds tight to the line that disappears into a frigid, murky Lake Erie. The three men peer anxiously over the edge of a weather-beaten tugboat, 3-1/2 miles off Cleveland’s downtown shore. At the end of the line is an 80-pound prize – not a monster fish, but a $20,000 sonar that measures ice thickness. It’s vital information, if wind turbines are to rise in these waters, near Cleveland’s water-intake crib. The sonar – essentially, an upside-down fish finder, Wagner says – will sit till early April, pinging out sound waves that gauge the thickness of ice overhead. To calculate the power of moving ice, Matthiesen and others at Case’s Great Lakes Institute for Energy Innovation will link the data on ice thickness with the movement of ice floes. A camera mounted nearby on the city’s water-intake crib is tracking that movement. “ Nobody has this kind of data,” said Matthiesen, a task force member. “We’ve got to have it.” http://www.chiefengineer.org/content/content_display.cfm/seqnumber_content/3762.htm