The Circulation in the Japan/East Sea derived from operational Korea Ocean Prediction System (KOPS)

Abstract

The Japan/East Sea is a large semi-enclosed sea located between the subtropical and subpolar zones. A three-dimensional primitive equation numerical circulation model (namely Operational Korea Ocean Prediction System (KOPS) based on the Pinceton Ocean Model) based on 18 layer sigma coordinates is used to study the circulation in the Japan/East Sea. New Generation Sea Surface Temperature (NGSST) and AVISO Sea Surface Height (Near Real Time data) data assimilation was performed with the model and the results are analyzed. Data assimilation has been carried out through univatiate statistical interpolation procedure, commonly called optimal interpolation technique on constant depth levels. The new values are interpolated back to hte original sigma coordinates. The surface circulation clearly shows the East Korea Warm Current (EKWC) and North Korea Cold Current (NKCC) along with the subpolar front. An anticyclonic warm core eddy present near Ulleung basin and this is observed all through the year. Surface circulation observed in this region is found to be very strong during summer. This activity is abating during winter in this region. Estimated geostrophic velocity values are also showing a similar feature. The SST and SSH data assimilation techniques were performed for better results. With the insertion of the SST data the results are improved. Further, the inclusion of SSH data brought better clarity to the results.