In this study, steric height variability in the East Asian Seas (EAS) has been analyzed by using ocean reanalysis intercomparison project (ORA-IP) data. Results show that there are significant correlations between ocean reanalysis and satellite data except the phase of annual cycle and interannual signals of the Yellow Sea. Reanalysis ensemble derived from 15-different assimilation systems depicts higher correlation (0.706) than objective analysis ensemble (0.296) in the EAS. This correlation coefficient is also much higher than that of the global ocean (0.441). For the longterm variability of the thermosteric sea level during 1993-2010, a significant warming trend is found in the East/Japan Sea, while cooling trend is shown around the Kuroshio extension area. For the halosteric sea level, a dominant freshening trend is found in the EAS. However, below 300 m depth around this area, the signal-to-noise ratio of the linear trend is generally less than one, which is related to the low density of observation data.

본 연구에서는 3차원 순환 모델인 MOHID (MOdelo HIDrodinâmico) 모델을 적용하여 한반도를 포함한 동아시아 해역의 2016년 해황 변동을 재현하였다. 재현 결과는 객관 분석장(EN4, ARMOR3D, AVISO, SIO 자료)과 현장 관측 자료(정선 해양 자료, 부이 자료)를 사용하여 검증하였다. 검증 결과 MOHID로 재현된 수온, 해면 고도 편차, 표층 유속 및 혼합 층 깊이 등의 전반적인 해황 구조가 동아시아 해역의 객관 분석 자료들과 유사하게 나타났다. 특히 연안의 부이 자료와 비교하였을 때, 표층 수온 및 해면 고도 편차의 상관 계수는 모두 0.8 이상이며, 표준화된 표준편차는 0.85-1.15의 값을 보였다. 그러나 여름철 동해의 수온 약층의 구조 및 황해와 남해의 강한 성층 현상 재현에 관한 추가적인 개선이 필요할 것으로 분석되었다.

Eight different data sets are examined in order to gain insight into the surface heat flux traits of the East Asian marginal seas. In the case of solar radiation of the East Sea (Japan Sea), Coordinated Ocean-ice Reference Experiments ver. 2 (CORE2) and the Objectively Analyzed Air-Sea Fluxes (OAFlux) are similar to the observed data at meteorological stations. A combination is sought by averaging these as well as the Climate Forecast System Reanalysis (CFSR) and the National Centers for Environmental Prediction (NCEP)-1 data to acquire more accurate surface heat flux for the East Asian marginal seas. According to the Combination Data, the annual averages of net heat flux of the East Sea, Yellow Sea, and East China Sea are −61.84, −22.42, and −97.54Wm−2 , respectively. The Kuroshio area to the south of Japan and the southern East Sea were found to have the largest upward annual mean net heat flux during winter, at −460- −300 and at −370- −300Wm−2 , respectively. The long-term fluctuation (1984-2004) of the net heat flux shows a trend of increasing transport of heat from the ocean into the atmosphere throughout the study area.

Satellite data, with sea surface temperature(SST) by NOAA and sea level(SL) by Topex/poseidon, are used to estimate characteristics on the variations and correlations of SST and SL in the East Asian Seas from January 1993 through May 1998. We found that there are two climatic characteristics in the East Asian seas: the oceanic climate, the eastern sea of Japan, and the continental climate, the eastern sea of China, respectively. In the oceanic climate, the variations of SL have the high values in the main current of Kuroshio and the variations of SST have not the remarkable seasonal variations because of the continuos compensation of warm current by Kuroshio. In the continental climate, SL has high variations in the estuaries(the Yellow River, the Yangtze River) with the mixing the fresh water and the saline water in the coasts of continent and SST has highly the seasonal variations due to the climatic effect of continents. In the steric variations of summer, the eastern sea of Japan, the East China Sea and the western sea of Korea is increased the sea level about 10∼20㎝. But the Bohai bay in China have relatively the high values about 20∼30㎝ due to the continental climate. Generally the trends of SST and SL increased during all periods. That is say, the slopes of SST and SL is presented 0.29℃/year and 0.84㎝/year, respectively. The annual and semi-annual amplitudes have a remarkable variations in the western sea of Korea and the eastern sea of Japan. In the case of the annual peaks, there appeared mainly in the western sea of Korea and the eastern sea of Japan because of the remarkable variations of SL associated with Kuroshio. But in the case of the semi-annual peaks, there appeared in the eastern sea of Japan by the influence of current, and in the western sea of Korea by the influence of seasonal temperature, respectively. From our results, it should be believed that SST and SL gradually increase in the East Asian seas concerning to the global warming. So that, it should be requested to the international co-operation against to the change of the abnormal climate.