Analyzing The Trends Of Monthly Great Lakes Water Levels Using Modified Mann Kendall Test

Trends in the monthly levels of five Great Lakes in the Midwest region of USA were examined in this study. For this purpose, 100 years of monthly lake levels of Lake Superior (at Duluth, MN), Lake Michigan (Calumet Harbor, IN), Lake Erie (at Buffalo, NY), Lake Huron (Harbor Beach, MI) and Lake Ontario (at Oswego, NY) were downloaded from NOAA web site. A modified version of seasonal regional Mann Kendall Test was developed which can handle regional analysis by dividing the data into different seasons. In this study, the data were divided in to 12 segments by considering every month and individual station trends and regional trends were studied. Mann Kendall Test Statistics "s" for different months were captured and examined in this study.