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You are here : eLibrary : Ice Research and Engineering : 22nd Symposium_Singapore (2014) : THEME 2- RIVER, LAKE AND RESERVOIR ICE : STANDING WAVES DURING ICE BREAKUP IN A POLAR LAKE
STANDING WAVES DURING ICE BREAKUP IN A POLAR LAKE
Author : Georgiy Kirillin, Christof Engelhardt, Alexander Forrest, Kelly Graves, Bernard Laval, Matti Lepp?ranta, William Rizk
Strong wind events play a crucial role in breaking the seasonal ice sheet in lakes and marginal seas. Still, the mechanism of ice break-up is poorly investigated. We demonstrate that, apart from the obvious effect of horizontal drift, wind produces basin-scale standing waves (seiches) under ice, which, in turn, may essentially contribute to breaking the ice sheet and accelerate ice melting. An extensive dataset on lake physical properties during the ice breakup has been acquired in spring 2013 in polar Lake Kilpisjarvi, Finland. The high-resolution records of pressure, current velocities and water temperature revealed continous oscillatory motions with periods of 10 to 25 min. The spectral energy peaks resided on frequencies corresponding to the first three eigenfrequencies of the lake indicating the oscillations are produced by the seiche movements at the lake surface. In agreement with previous studies, seiches persisted under cover. During the period preceding the breakup, amplitudes of the lake surface oscilations under ice did not exceeded 1mm. The ice breakup was associated with a strong wind event and a 10 times increase of seiche amplitudes under ice. We suggest that vertical motions of the soft ice sheet significantly accelerated its melting, so that at the lake surface covered by icce to 80 percent, the ice completely melted within 10-15 hours.
File Size : 2,029,616 bytes
File Type : Adobe Acrobat Document
Chapter : Ice Research and Engineering
Category : 22nd Symposium_Singapore (2014)
Article : THEME 2- RIVER, LAKE AND RESERVOIR ICE
Date Published : 13/07/2016
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