Analysis of the Spatiotemporal Variability of Pacific Water Propagation in the Sea of Okhotsk Based on the Lagrangian Approach

The eastern Sea of Okhotsk is one of the most important areas of the World Ocean in terms of fisheries. The high productivity of this region is supported, in particular, by the inflow of waters from the Pacific Ocean. The process of inflow and propagation of these waters into the sea is poorly understood. In this paper, altimetry data on current velocities and the Lagrangian approach are used to track the events of the inflow of waters of Pacific origin into the Sea of Okhotsk and to characterize their evolution. Daily values of two types of indices describing propagation of Pacific waters in the Sea of Okhotsk were obtained based on the data on the location and shape of water intrusions. It is shown that in winter such waters are usually located closer to Kamchatka, and in summer, farther from the coast. In 1998, 2003, 2010, 2013, 2017, and 2019, Pacific waters penetrated the farthest distance to the north. Analysis of the morphometric characteristics of the intrusions showed that after reaching the maximum area of the intrusion, its shape quickly becomes more complex. The centroids of the largest intrusions are usually located in the band 152°–154° E. Based on the developed indices it is shown that the inflow of water from the ocean into the sea has increased since 2010.