Submesoscale eddy structures of Lake Ladoga according to radar data of Sentinel-1 for the warm period 2019–2022

Abstract

Summary of the results of the analysis of the spatiotemporal variability of sub-mesoscale eddy structures on the surface for Lake Ladoga from May to October 2019–2022 is conducted. The original data consists of over 1000 high-resolution Sentinel-1A/B images. It has been found that eddy structures are widely distributed during the warm period of the year in the lake’s basin. A total of 496 surface manifestations of eddies were recorded. The average diameter of the observed structures was 2 km. More than 90% of the recorded eddies belong to the sub-mesoscale variability range. Cyclonic rotation was observed in 84% of the structures. The seasonal maximum of eddy activity is observed during the development of stable stratification over most of Lake Ladoga. Eddies are most frequently encountered to the north and northeast of Valaam Island in areas with depths of around 100 meters, but in close proximity to the unevenness of the seabed. Eddy formations are often observed on the cold side of the frontal boundary during the existence of the spring thermocline, indicating their important contribution to water exchange and mixing processes.