동해 순환모델에 대한 3차원변분동화기법의 적용

Abstract

Recently, we have assimilated satellite-borne sea surface temperature and sea surface height data, and temperature profiles into the East/Japan Sea Regional Ocean Model (DA-ESROM) from 1993 to 2002 using a 3-dimensional variational data assimilation scheme. Comparing with the results from Mitchell et al. (2005), 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 100m 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. Analyzing the results of the DA-ESROM, we have investigated spatial and temporal variability of the North Korean Cold Current (NKCC) in the East/Japan Sea. The monthly mean transport of the NKCC shows a clear seasonal variation with a range of about 0.35 Sv (=106m3/s), which increases from its minimum (about 0.45 Sv) through December-January to March, decreases from March to May, and then increases again to the maximum (about 0.8 Sv) in August-September. Interannual variation of the NKCC , however, is lager than the seasonal variation with a range of about 1.0 Sv. Model results show that the NKCC carries the North Korean Cold Water (NKCW) southward through the two different paths along the Korean coast and along 130°E.