Lake Huron climatology, inter-lake exchange and mean circulation

Selected key features of the physical limnology, hydrology and climate influencing Lake Huron is presented. The lake is deep (229 m), consists of four interconnected bodies of water and currently there are no diversions into or out of the lake. Long-term annual summaries of meteorological and hydrological variables show that the lake affects spatial distributions across the basin. An estimate of the long-term hydrologic budget shows the relative importance of the major inflows, outflows and net basin supply. Long-term monthly average water level is 176.6 m. Monthly mean total heat flux ranges from −155 W m^{− 2} in December to 154 W m^{− 2} in June. Light attenuation is higher in Saginaw Bay and the nearshore compared to the mid-lake. Ice extent can be an important factor in the Lake Huron system with values ranging from < 10% to > 90% depending on winter severity. Surface and mean lake temperature for shallow North Channel are similar, however, large volumes of main Lake Huron and Georgian Bay results in mean temperatures nearly 10°C less than surface temperatures in summer. Inter-lake exchange at the Straits of Mackinac is about 2 cm s^{− 1} but fluctuating flows can be up to 30 times larger. The averaged summer and winter circulation shows cyclonic patterns for Lake Huron.