MAIN FEATURES OF THE THERMAL REGIME OF LAKE-LADOGA DURING THE ICE-FREE PERIOD

The thermal regime of Lake Ladoga during the ice-free period is determ ined by primarily incoming solar radiation, wind-induced mixing and th e depth distribution. The variation of water surface temperature with time for different areas of the lake is discussed using temperature me asurements obtained by means of an aircraft-mounted IR-radiometer. Max imum values of water surface temperature in these areas, as well as th e time lags between the areas are determined. Mean rates of temperatur e variation for the periods of warming and cooling of the lake are als o determined. A formula for determining the location of the spring fro ntal zone at different stages of water warming is suggested. The pecul iarities of the interaction of stratified and isothermal waters in the frontal zone, the slope of the frontal zone and the thermal balance c omponents are discussed on the basis of specialized field measurements by using ships and aeroplane. The scales of temperature inhomogeneiti es are obtained based on computation of 2D spatial correlation functio ns.