Weather and Waves on Lake Superior: An Intercomparison of Data from Two Buoy Designs

Session: 59. - Innovative Monitoring across the Great Lakes

Holly Roth, Northern Michigan University, [email protected]
Norma Froelich, Northern Michigan University, [email protected]
John Lenters, University of Wisconsin-Madison, Center for Limnology, [email protected]

Abstract

Since 2015, three nearshore GLOS weather/wave buoys have been deployed along the southeastern shore of Lake Superior. For six weeks in 2015, two of the buoys were co-located at Granite Island (Marquette, Michigan) to compare weather/wave measurements between two different buoy designs. A TIDAS-900 buoy was moored 150 meters south of the island, while a smaller NexSens CB-450 buoy was anchored 400 meters north of the island. The two buoys each use the same wave sensor, but have hulls of different size and shape. The primary goal of this research was to determine whether the different buoy designs resulted in significantly different wave height measurements. A second objective was to assess the impact of instrument height and the wind/wave “shadow” on the leeward side of Granite Island. Examination of time series and scatterplots of air and water temperature, wind speed and direction, and wave height showed slight variations due to the height of the weather instruments above the lake surface and wave dissipation from Granite Island. Little difference in wave height was found, however, when both buoys were outside the wind/wave shadow of the island, providing confidence in subsequent buoy wave height measurements for 2015-2017, when deployed at different locations.

1. Keyword
Buoys

2. Keyword
comparison studies

3. Keyword
Lake Superior

4. Additional Keyword
waves

5. Additional Keyword
weather