Winter heat content and summer stratification in Lake Superior

Abstract

The Large Lakes Observatory has deployed subsurface moorings in Lake Superior since 2005. Temperature data from these moorings is used to constructcomplete subsurface thermal profiles for most years between 2005-2022. Total lake heat content, which is a function of temperature and depth, is computed from this data in order to analyze heat flux in Lake Superior and gain further insight on winter heating influences of summertime surface warming. Relationships among winter seasonal characteristics such as heat content, ice cover, and air temperature are explored using linear regression techniques. From surface water temperature data, yearly date of summer stratification is determined to examine connections with winter heat content and ice cover. Analysis of fit parameters indicates that winter heat content holds the stronger relationship, and it is shown to be a reliable predictor of summer stratification timing.