High-resolution circulation forecasting of the Maenggol Channel, south coast of Korea

The Maenggol Channel and Uldolmok Strait, located on the south-west coast of Korea, have notably strong and complex currents due to tidal effects and to local geological factors. In these areas, electric power has been generated using strong tidal currents, the speed of which is more than 3 m/s during spring tides. The region also provides a shortcut for navigation. These tidal conditions are therefore sometimes useful, but may also cause terrible accidents or severe economic damage, in the absence of accurate information regarding ocean conditions. In April 2014, the passenger ferry MV Sewol capsized in the Maenggol Channel, with 295 passengers killed and 9 still missing. While this was unquestionably a man-made disaster, strong currents were one of the contributing causes. It was also difficult to conduct scuba diving rescue operations given strong current speeds,and accurate prediction of the time when the tide would turn was thus critically needed. In this research, we used the high-resolution coastal circulation forecasting system of KOOS（Korea Operational Oceanographic System） for analysis and simulation of strong tidal currents in such areas with many small islands, using measurements and modeling from this research area. For accurate prediction of tidal currents, small grid size-modeling was needed,and in this study, we identified a suitable grid size that offers efficiency as well as accuracy.

近700ka来西菲律宾海沉积物来源和东亚冬季风演化的常量元素记录

为系统了解西菲律宾海700ka以来柱状沉积物的常量元素组成特征及其物源和古环境指示意义,对本哈姆高原上MD06-3047孔的221个样品进行了粒度和常量元素组成分析,并测试了其中16个典型沉积物中碎屑态的常量元素含量.物源判别图解及R型因子分析结果均表明钻孔中主要氧化物含量在垂向上的变化主要受控于附近火山碎屑物质沉积作用和陆源风尘物质输入,而海洋生物沉积作用及热液活动的影响较小.特别是以Al2O3和K2O为代表的陆源风尘因子的得分变化表现出明显的冰期-间冰期旋回特征,并与南极冰芯的古温度记录及中国黄土的东亚冬季风记录间具有良好可比性,进而为揭示东亚冬季风强度及风尘源区干湿条件制约下的研究区内陆源风尘物质输入演化历史提供了新的替代性指标.

Sediment provenance discrimination in northern Okinawa Trough during the last 24 ka and paleoenvironmental implication:rare earth elements evidence

Rare earth elements （REE） compositions and discriminant function were successfully used to examine high resolution sediment source changes in the northern Okinawa Trough over the last 24.1 ka, especially for the influence from the Yellow River and the Tsushima Warm Current （TWC） that has not been well solved. Variations of these parameters were clearly divided into three distinct depositional units. During Interval 1 （24.1-16.0 ka BP）, the paleo-Yellow River and the paleo-Yangtze River mouths were situated near the studied area and could have played major roles in the sedimentation therein. In Interval 2 （16.0-7.3 ka BP）, these river mouths gradually retreated with global sea-level rise, leading to less fluvial inputs from them to the northern Okinawa Trough. Meanwhile, formation of the TWC could carry some sediment loads of Taiwan to the studied core, especially during its late phase （8.0-7.3 ka BP）. Modem oceanographic conditions, with a predominance of the TWC, were finally established since the beginning of Interval 3, causing more ten＇igenous contribution from Taiwan to the studied area. Subsequently, modem depositional environments mainly influenced by the Yellow River, the Yangtze River, and the TWC were finally formed.

Sediment provenance and evolution of the East Asian winter monsoon since 700 ka recorded by major elements in the West Philippine Sea

To synthetically realize the character of major-element compositions as well as its significance for provenance and paleoenvironment recorded in core sediments of the West Philippine Sea over the last 700 ka,grain size and major elements of 221 bulk sediments,together with major-element compositions in the detrital phase of 16 typical samples,in core MD06-3047 collected from the Benham Rise were analyzed.Both discrimination plot and R-mode factor analysis indicate that vertical changes of major elements are mainly controlled by the sedimentation of nearby volcanic matter and the eolian dust input,whereas influences from marine biologic deposition and hydrothermal activity are minor.In particular,Al2O3 and K2O are representative of an eolian dust factor.The variation in the eolian dust factor score is characterized by the obviously glacial-interglacial periodicity and can be well compared with the paleotemperature record of the Antarctic ice core and the evolution of the East Asian winter monsoon(EAWM) recorded in the Chinese loess sequence,and then offers a new proxy for the evolution history of eolian dust input into the study area that is controlled by the EAWM intensity and aridity in the continental source regions of atmospheric dust.