Simple linear models of coastal setup and seiching behavior across the Laurentian Great Lakes

Abstract

Storm surges and seiches are two dynamically distinct behaviors of lakes that contribute to coastal sea level fluctuations on short time scales and can have significant societal and ecological impacts. Most of the emphasis in the existing Laurentian Great Lakes literature on storm surges focuses on wind-driven storm surges on Lake Erie, due to their large magnitudes and major population centers at both ends of the lake. On Lake Superior, however, the primary driver of coastal setup is atmospheric pressure gradients, which depress water levels at one end and increase them at the other. Lakes Michigan, Huron, and Ontario are intermediate, and both wind forcing and atmospheric pressure gradients contribute to coastal setup. The primary driver of this difference in response is lake depth, which is explored here using simple linear theory. In addition, lake depth plays an important role in the character of the subsequent seiche response of lakes; in shallow lakes such as Erie, bottom drag can damp out seiching behavior quickly, whereas in deep lakes like Superior, seiches can persist for many oscillations. A survey of large lakes worldwide suggests a wide range of behaviors.