The 1998 coastal turbidity plume in Lake Michigan

In this paper, numerical models of coastal circulation, wind-waves, and sed iment transport are applied to the March 1998 turbidity plume event in Lake Michigan to investigate the role of wind-induced circulation in the offsho re transport of sedimentary material in Lake Michigan. Computer visualizati on is used to compare model results to the evidence of cross-isobath transp ort suggested in satellite imagery. Model results showed that circulation i n Lake Michigan is highly episodic since it is almost entirely wind-driven in early spring. The characteristic wind-driven circulation pattern in the lake consists of two counter-rotating gyres, a counterclockwise-rotating gy re to the right of the wind, and a clockwise-rotating gyre to the left. The gyres are separated by a convergence zone along the downwind shore with re sulting offshore flow and a divergence zone along the upwind shore with ons hore flow. This two-gyre circulation pattern with offshore flow was very cl early seen during a northerly wind event in March 1998 in southern Lake Mic higan. The strongest sediment resuspension occurred in the southern lake an d the shallow waters along the coastline. This is because of the larger wav es in southern Lake Michigan due to the dominant northerly wind in this ear ly spring period. The two most significant sediment resuspension events wer e detected in the model results during the two storm events. Although resul ts from the sediment transport model agree qualitatively with satellite ima gery, they fail to simulate the initial eddy-like structure of the plume. V isualization is shown to be an effective tool for interpreting the complex turbidity patterns in the satellite imagery of the turbidity plume. (C) 200 0 Academic Press.