Observations of the Korea Strait bottom cold water

Abstract

In this study, a set of 13 bottom mounted acoustic Doppler current profilers with temperature and pressure sensors were deployed in the Korea Strait for 11 months in 1999–2000. The overall purpose of the project was to understand the linkages between the East Asian marginal seas. Our focus in this paper is on an intrusion of bottom cold water from the East Sea which appears on the western side of the Korea Strait (Korea Strait Bottom Cold Water, KSBCW). In contrast to previous work, we did not find a yearly cycle in its appearance with maximum in summer and minimum in winter. Rather, sustained intrusions occurred in May/June and again in December/January. Bottom currents during the times of its appearance showed only limited advective intrusion with recycling back to the East Sea. Monthly scale bottom temperature records in the intrusion area were negatively correlated with the cross-strait bottom pressure anomaly, a measure of geostrophic transport through the Strait. Our hypothesis is that when geostrophic transport is low the bottom cold water intrudes, and when it is high the cold water is prevented from intruding. Prediction of the bottom cold water appearance, then, would depend on prediction of the geostrophic transport.