Axisymmetric circulation driven by marginal heating in ice-covered lakes

• Published in: Geophysical research letters Vol. 42; no. 8; pp. 2893 - 2900
• Main Authors: Kirillin, G. B., Forrest, A. L., Graves, K. E., Fischer, A., Engelhardt, C., Laval, B. E.
• Format: Journal Article
• Language: English
• Published: Washington Blackwell Publishing Ltd 28.04.2015; John Wiley & Sons, Inc
• Subjects: Atmosphere; Atmospheric circulation; Axisymmetric; Basins; Boundaries; Buoyancy; Buoyancy flux; Circulation; Continental shelves; Cooling; Coriolis force; Density; density underflows; Flow; Fluctuations; Freshwater; Freshwater lakes; Geophysics; Gravitation; Gravity; Gravity currents; Heat; Heat flux; Heat transfer; Heating; Ice; Ice cover; ice-covered lakes; Inland water environment; Katabatic winds; Lake ice; Lakes; Ocean circulation; Return flow; rotating gravity currents; Shorelines; Shores; Slopes; sloping topography; Temperature; Temperature effects; Transport; Transport processes; Underflow; Upwelling; Water column; Water scarcity; Wind; Winds; Finland, Lappi, Kilpisjaervi L
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2014GL062180

Below the temperature of maximum density (TMD) in freshwater lakes, heating at the lateral margins produces gravity currents along the bottom slope, akin to katabatic winds in the atmosphere and currents on continental shelves. We describe axisymmetric basin‐scale circulation driven by heat flux at the shorelines in polar Lake Kilpisjärvi. A dense underflow originating near the shore converges toward the lake center, where it produces warm upwelling and return flow across the bulk of lake water column. The return flow, being subject to Coriolis force, creates a lake‐wide anticyclonic gyre with velocities of 2–4 cm s‐1. While warm underflows are common on ice‐covered lakes, the key finding is the basin‐scale anticyclonic gyre with warm upwelling in the core. This circulation mechanism provides a key to understanding transport processes in (semi) enclosed basins subject to negative buoyancy flux due to heating (or cooling at temperatures above TMD) at their lateral boundaries. Key Points New type of Coriolis‐balanced circulation in ice‐covered lakes is discovered The bottom slope plays a key role in acceleration of the of anticyclonic flow The only driver is the buoyancy sink along the shore: general for coastal flows