Observations of Currents in Saginaw Bay, Lake Huron

Abstract

During June 1991 through June 1994, six current meter moorings were deployed in the outer region of Saginaw Bay, Lake Huron to study the bay's dynamics and interaction with Lake Huron. Two current meters were configured on each subsurface mooring at 14 m below the water surface and 2 m above the bottom, and current speed, direction, and water temperature were recorded at 15 minute intervals. These data represent nearly 1.2 million observations and are the longest continuous set of observations conducted anywhere in Lake Huron and the first extensive set of winter observations conducted in Saginaw Bay. The winter months showed the highest mean currents from the moorings closest to Lake Huron, whereas the stratified season showed high mean currents at the moorings located in the bay proper. There was little consistency in mean flow vectors other than the bottom currents at the southeastern mooring which showed consistent flow from the bay into Lake Huron. Only a small fraction of the kinetic energy was contained in the mean flow. The variability in the orientation of the principal axes of variation on semi-annual to inter-annual time scales suggests using caution in generalizing about circulation patterns based solely upon limited data sets.