Marine heat waves: Why the East Sea experienced extreme conditions in 2021
[...]
An anomalous few weeks of extremely high temperatures occurred in the East Sea (Sea of Japan, northwest Pacific) during the summer of 2021, when one particular current experienced record-breaking changes in dominant patterns, first significantly intensifying before weakening. This was the East Korea Warm Current (EKWC), which is a western boundary current off the east coast of South Korea that occurs due to intensification of marine conditions in the west of the ocean basin, and carries warm water from the tropics poleward.
New research published in Frontiers in Marine Science has investigated the factors that likely resulted in this unusual event. Doctoral researcher Gyundo Pak, of the Korea Institute of Ocean Science and Technology, and colleagues determined a northward shift of the EKWC up to 40°N at the end of July 2021, alongside increased current speeds of 1.16m/s, measured from moorings on the seabed. These moorings also measured an increased volume of water transported via the EKWC during this time (more than double normal levels) into the East Sea, as it is a key inflow branch to the basin. However, by the middle of August, a rapid deceleration of the current saw it weaken to summer background levels of 0.5m/s.
[...]