Observations of the Intermediate and Benthic Nepheloid Layers in Southern Lake Michigan during the Summer of 1995

摘要

During the summer of 1995 time series measurements of water transparency, water temperature, and current velocity were made at stations located in 28, 58, and 100 m of water in southern Lake Michigan. Inertial internal waves were the dominant feature of the lake circulation. These waves caused variations in the thickness and in the vertical distribution of suspended sediment in the benthic nepheloid layer. An intermediate nepheloid layer located at the base of the thermocline was also affected by the inertial waves. This layer moves up and down in response to movement of the thermocline due to both inertial waves and to upwelling and downwelling events. Although a direct link between inertial wave action and changes in the benthic nepheloid layer could not be established, the data strongly suggest that the layer is maintained by local resuspension due to a combination of inertial wave action and longer-term processes.