Interseasonal Variability in Methane Concentrations and Fluxes at the Water–Atmosphere Boundary in the Western Sea of Okhotsk

— Intra-annual variability in methane fluxes at the water–atmosphere boundary was shown for the first time in the water area of the Sea of Okhotsk east of Sakhalin Island. The variability in methane fluxes is determined by the presence and activity of submarine methane sources and is related to seasonal changes in the hydrological and hydrochemical parameters of seawater and current structure in this region. In spring and autumn, the average fluxes are higher than in those in summer. The methane flux from the sea surface decreases during summer water modification and the increase in stratification. In autumn, methane accumulated in transitional waters is emitted into the atmosphere due to seasonal water convection and high average wind speed.