Under-ice circulation, modified by the Earth's rotation, in an arctic lake

• Main Authors: Graves, KE, Laval, BE, Forrest, AL, Kirillin, G
• Format: Conference Object
• Language: English
• Published: International Association of Hydro-Environment Engineering and Research 2014
• Subjects: Engineering; Fluid mechanics and thermal engineering; Geophysical and environmental fluid flows; Arctic; Arctic Lake
• Online Access: http://www.iahr-ice2014.org/; http://ecite.utas.edu.au/94129

Recent field observations and numerical modelling challenge the commonly held view that fluidmotion under lake-ice is insignificant. This growing body of evidence indicates that under-icecirculation is an important mechanism for lateral and vertical transport of heat and pollutants inice-covered lakes. Using direct measurements of temperature, conductivity and water columnvelocities in an ice-covered arctic lake, further field observations of circulation on a basin-widescale over the entire lake depth are presented. These observations were made during a 2013 fieldresearch campaign in Lake Kilpisjarvi, Finland (approximately 69degree N, 21degree E). During the fieldobservation period the entire water column was colder than the temperature of maximum density.Orthogonal density profiles of temperature show an approximately 500m wide upwelled densityanomaly beneath the ice-cover. This anomaly consisted of warm, upwelled bottom water.Repeated temperature profiles, collected over a two-day period, show that the density anomalypersisted for the observation period of three days. Acoustic Doppler Current Profilermeasurements of water column velocity show anti-cyclonic circulation around the densityanomaly. The observed density profile and velocity measurements are shown to be consistentwith a cyclogeostrophic force balance. These measurements show basin-wide circulation beneathice-cover. These results contribute to the knowledge of winter hydrodynamics in lakes and thegrowing body of observation of lateral and vertical transport under-ice