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Hydro-climate Research

Primary Investigator - Drew Gronewold - GLERL

Related GLERL Publications (.pdf)

Modeling seasonal water levels and the components that impact them adds to our understanding of how the Great Lakes basin changes over the course of months and years. GLERL scientists have been conducting research on the regional water budget since the early 1980's. Synthesizing data on precipitation, runoff, and evaporation for the basin and using that data to develop predictive tools has long been one of GLERL's primary missions. The interaction between seasonal water level dynamics, ice cover, and over-lake evaporation is an area of current research.

Over-lake evaporation and Great Lakes water levels

The primary drivers of Great Lakes water levels are precipitation and evaporation over the lakes. Using a novel visualization tool called the Great Lakes Hydro-Climate dashboard and simulated over-lake evaporation, GLERL has shown that a period of above-average over-lake evaporation beginning in the late 1990's is highly correlated with the recent 15-year period of unusually low water levels on Lakes Superior, Michigan, and Huron. Measurements of over-lake fluxes are now being gathered in several of the Great Lakes. GLERL researchers are supporting these efforts and will use this data to improve both our understanding of these complex air-water interactions and our predictive tools.

Aerial photo of White Shoal light in northern Lake Michigan. January 13, 2014. Credit: D. Moehl and Great Lakes Air.

Installation of new equipment on the White Shoal Lighthouse in northern Lake Michigan established telemetry so that the data being gathered at the eddy covariance station there can be monitored and collected at GLERL. An eddy covariance station measures atmospheric fluxes that allow over-lake evaporation to be estimated.

The above image from the Great Lakes Hydro-Climate Dashboard shows the relationship between annual average water levels (dark dashes) and estimated over-lake evaporation for Lakes Superior, Michigan, and Huron from 1950 to present. Orange vertical bars represent years when over-lake evaporation was greater than average, while teal vertical bars indicate years of below-average over-lake evaporation. Large increases in over-lake evaporation starting in the late 1990's on these lakes coincide with a sustained period of below-average water levels.

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