Observations of the Vertical Structure of the Keweenaw Current, Lake Superior
Document Type
Article
Date of Original Version
1-1-1993
Abstract
The vertical structure of the Keweenaw Current, on the south shore of Lake Superior, is studied using data from an autonomously profiling current meter moored 2 km offshore (depth = 100 m). Vertical profiles of temperature, current speed, and current direction show current direction strongly aligned east-west with the topographic contours, with currents below 50 m depth most frequently flowing eastward at speeds of 6-12 cm/s, and those above 50 m depth flowing sometimes eastward and sometimes westward at speeds of 10-20 cm/s. Principal component analysis on profiles of eastward velocity reveals two vertical modes which have approximately the barotropic and first baroclinic modal form. The dominant “barotropic” mode contains 90% and 82%, respectively, of the eastward velocity and temperature variances. Strong occurrences of this mode (full-water-column eastward flows with speeds up to 37 cm/s) are related to strong increases in the temporal integral of longshore wind stress, consistent with coastal jet theory. The “baroclinic” mode, containing 6% of the eastward velocity variance, is dominant only during periods of weak longshore wind stress. Its 4-day period is comparable with a typical interval between atmospheric frontal disturbances. © 1993, International Association for Great Lakes Research. All rights reserved.
Publication Title, e.g., Journal
Journal of Great Lakes Research
Volume
19
Issue
2
Citation/Publisher Attribution
Viekman, Bruce E., and Mark Wimbush. "Observations of the Vertical Structure of the Keweenaw Current, Lake Superior." Journal of Great Lakes Research 19, 2 (1993). doi: 10.1016/S0380-1330(93)71233-2.