A Mesocyclone over the Northern Sea of Japan in February 2013

— The article considers a particular event in the influence of a mesoscale cyclone (MC) on the northern Sea of Japan on February 10–11, 2013. The passage of the MC was accompanied by a sharp increase in wind to storm conditions, an almost twofold decrease in total heat transport, and a fourfold increase in the momentum flux. Perturbations of the hydrological characteristics in the wake of the MC estimated from data of two Argo floats were traced to a depth of 300 m off the west coast of Hokkaido and up to ~100 m in the deep-water region, caused by the difference in the background stability of the vertical structures. Several estimates of the contribution of various factors to the observed variability of the upper sea layer are given.