A three-dimensional model of Lake Superior with ice and biogeochemistry

The formation of winter ice on Lake Superior has been shown to be important in determining the annual thermal cycle of the lake and long-term trends of surface water temperature increase. However, modeling studies of Lake Superior to date have not included dynamic and thermodynamic ice cover. These physical characteristics of the lake in turn can have significant impacts on biogeochemical cycling within the lake. We present a new three-dimensional model of Lake Superior that includes a dynamic and thermodynamic ice model and a biogeochemical model. Results from the model forced by observed meteorological conditions for the period 1985 to 2008 are discussed and compared with available observations. Modeled long-term interannual trends in increasing water temperature and decreasing ice cover are compared with observed rates. In the model, total annual gross primary productivity is found to correlate positively with mean annual temperature and negatively with mean winter ice-cover magnitude. (C) 2011 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved.