Big Lake - Big Waves: A historical climatology of offshore wave heights on Lake Superior

Session: 49. - Big Lakes - Small World: IAGLR Teams with the European Large Lakes Symposium in 2018

John Lenters, University of Wisconsin-Madison, Center for Limnology, [email protected]

Abstract

Lake Superior is the world’s largest freshwater lake by surface area, and given its midlatitude location, the “Big Lake” is notorious for strong autumn and winter storms and large wave events. Perhaps the most well-known storm occurred in November of 1975, resulting in the sinking of the Edmund Fitzgerald and the solidifying of the “Gales of November” in Great Lakes shipwreck lore. The storm was thought to have brought significant wave heights averaging 30-35 feet during the height of the storm, with much higher maximum wave heights from individual, rogue waves. With the advent of data buoys on Lake Superior in 1979, we now have a nearly 40-year record of wave activity during the ice-free seasons of May-November. Here, we present a climatological analysis of significant wave height data from three offshore buoys on Lake Superior, including an examination of the mean seasonal cycle of wave activity, the timing and magnitude of maximum wave events, and a comparison with the recent 28.8-foot nearshore wave event on October 24, 2017. Finally, the occurrence of some late-season storms after the typical date of buoy retrieval suggests that many large wave events continue to go unmeasured, even in the modern buoy era.

1. Keyword
Lake Superior

2. Keyword
waves

3. Keyword
atmosphere-lake interaction