THE KEWEENAW CURRENT, A REGULAR FEATURE OF THE SUMMER CIRCULATION OF LAKE SUPERIOR.
WISCONSIN UNIV MADISON DEPT OF METEOROLOGY
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Infrared radiometer surveys of Lake Superior during the summer of 1964 and 1965 have shown that a band of warm water separated by a sharp thermal gradient appears along the north coast of the Keweenaw Peninsula in late June and persists at least into August. The sub-surface thermal structure in this region indicates a steep slope of the geodynamic surfaces with the pressure gradient directed offshore. Calculation of current velocity based on the geodynamic slopes gives velocities up to one knot. Direct observations confirm the existence of this current both with regard to location and estimated velocity. The current, for which the name Keweenaw Current is suggested, flows northeastward along the north coast of the Keweenaw Peninsula. It appears to be a boundary current and is probably maintained by the piling up of warm water along the south side of the lake by Ekman transport. It is shown that although the thermal bar effect may exist in early June, this phenomenon does not provide an explanation for the temperature and circulation pattern observed later in the season. Analysis of infrared radiometer data at intersections of flight tracks on a single day gave diurnal heating rates of 0.21 to 0.27 C.hr. Author
- Hydrology, Limnology and Potamology