Simulated Seasonal Water Temperature Cycles and Stratification in Large Lakes in Minnesota: Addendum to Project Report No. 410

Abstract

Information on seasonal water temperature cycles and temperature stratification in ten large lakes in Minnesota has been obtained by numerical simulation(Gao and Stefan, 1997). The ten lakes are Mille Lacs Lake, Red Lake, Lake of the Woods, Leech Lake, Lake Vermilion, Lake Kabetogama, Lake Winnibigoshish, Lake Pepin, Rainy Lake and Cass Lake. The lakes have surface areas of 63 to 3846 km2 and maximum depths from 6 m to 49 m. To do this study, a one-dimensional, unsteady, year-round, process-oriented model, MINLAKE 96, was used.

All lakes were simulated for the period from 1983 to 1990 except Mille Lacs Lake which was simulated from 1980 to 1990 in order to compare the simulation results with field data in 1981.

In the report by Gao ,:nd Stefan (1997), simulation results for the year 1990 were presented. Simulation results for all simulation years (1983 - 1990) have been assembled in this external memorandum. They include

• isotherms interpolated from simulated daily water temperature profiles, • tables for mean weekly water temperatures, and maximum and minimum daily water temperatures in each week at 1 m above the deepest point of the lakes, • figures for mean weekly water temperatures, and weekly maximum and minimum daily water temperatures in each week at 1 m above the deepest point of the lakes, • tables for mean annual water temperatures, plus/minus one standard deviation of daily values at 1 m above the deepest point of the lakes, • figures for mean annual water temperatures, plus/minus one standard deviation of daily values at 1 m above the deepest point of the lakes.

The results are assembled in the same order for each lake and without figure titles. Labels on each figure identify the information presented.