Reanalyzed products from a MOM3-based East Sea Regional Ocean Model with a 3-dimentional variational data assimilation module (DA-ESROM), have been compared with the observed hydrographic and current datasets in the Ulleung Basin (UB) of the East/Japan Sea (EJS). Satellite-borne sea surface temperature and sea surface height data, and in-situ temperature profiles have been assimilated into the DA-ESROM. The performance of the DA-ESROM appears to be efficient enough to be used in an operational ocean forecast system. Comparing with the results from Mitchell et al. [Mitchell, D. A., Watts, D. R., Wimbush, M., Teague, W.J., Tracey, K. L., Book, J. W., Chang, K.-I., Suk, M.-S., Yoon, J.-H., 2005a. Upper circulation patterns in the Ulleung Basin. Deep-Sea Res. II, 52, 1617-1638.], the DA-ESROM fairly well simulates the high variability of the Ulleung Warm Eddy and Dok Cold Eddy as well as the branching of the Tsushima Warm Current in the UB. The overall root-mean-square error between 100 m temperature field reproduced by the DA-ESROM and the observed 100-dbar temperature field is 2.1 °C, and the spatially averaged grid-to-grid correlation between the two temperature fields is high with a mean value of 0.79 for the inter-comparison period. The DA-ESROM reproduces the development of strong southward North Korean Cold Current (NKCC) in summer consistent with the observational results, which is thought to be an improvement of the previous numerical models in the EJS. The reanalyzed products show that the NKCC is about 35 km wide, and flows southward along the Korean coast from spring to summer with maximum monthly mean volume transport of about 0.8 Sv in August-September.
Bibliographical noteFunding Information:
We are grateful to Dr. D.R. Watts who supported the PIES data in the Ulleung Basin. Special thanks are directed to Dr. M. Hofmann who kindly provided the SOM code. The altimeter products were produced by Ssalto/Duacs and distributed by Aviso, with support from Cnes. The major part of this works was conducted with financial support by Agency for Defense Development under the contract UD031003AD. The first and seventh authors were supported at the final stage of this work by KORDI's research projects (PE9830Q and PG47100). The second author was supported by EAST-I Program of the Ministry of Maritime Affairs and Fisheries.
We wish to acknowledge PICES for supporting the publication of this special issue. We also wish to thank SEES (BK21), Seoul National University for organizing the CREAMS/PICES workshop through its EAST-I Program supported by MLTM (Ministry of Land, Transport and Maritime Affairs, Korea), and PICES, KORDI (Korea Ocean Research and Development Institute), and Pukyong National University for their co-sponsorship.
- 3-dimensional variational technique
- East Sea Regional Ocean Model
- East/Japan Sea
- North Korean Cold Current
- Oceanic currents
- Oceanic eddies
- Ulleung Basin