Generation of cyclonic gyre in large saline lake through differential warming

Abstract Circulation model of Lake Issyk‐Kul is compiled based on Princeton Ocean Model with real bathymetry and atmospheric and river runoff forcings. According to the model, the cyclonic circulation develops in the lake from May to January, when a seasonal thermocline is present, while in February through April it vanishes or changes for a weak anticyclonic circulation. Wind‐driven coastal jets and internal Kelvin waves intensify vertical mixing at a lateral periphery of the lake over sloping bottom. Due to enhanced vertical mixing and reduced depth, the water column warms up and cools down faster at the lateral periphery of the lake than in the deep central part. This, in view of geostrophic balance, causes cyclonic circulation in the period from late spring to early winter and the anticyclonic circulation during the rest of the year. River runoff does not play a primary role and only moderately contributes to the cyclonic circulation through the geostrophic adjustment of buoyant coastal discharges to the lake whose salinity is about 6 ppt. At the end of winter and beginning of spring, when river runoff is minimal, it is nevertheless capable of maintaining weak hydrostatically stable stratification in the coastal zone and thereby significantly weakening the development of cascading and deep‐water ventilation. Model simulations showed that the cyclonic circulation prevailing in Lake Issyk‐Kul would develop even without positive wind stress curl attributed to local winds.