Based on more than 30 years observed sectional temperature data since the 1960s, and compared with multi-year wind and Changjiang (Yangtze) River discharge data, spatial-temporal variations of the East China Sea Cold ...Based on more than 30 years observed sectional temperature data since the 1960s, and compared with multi-year wind and Changjiang (Yangtze) River discharge data, spatial-temporal variations of the East China Sea Cold Eddy (ECSCE) in summer was analyzed in relationship to ocean circulation and local atmospheric circulation. Empirical Orthogonal Function (EOF) and Singular Value Decomposition (SVD) analyses were applied to this study. The results show that: 1) The ECSCE in summer possesses significant interannual variabilities, which are directly associated with oceanic and atmospheric circulation anomaly. Main fluctuations demonstrate their falling in basically with El Nino events (interannual) and interdecadal variability. 2) The ECSCE in summer is closely related to the variation of the Yellow Sea Warm Current (YSWC) and the Changjiang River discharge. The stronger the YSWC, the more intensive the ECSCE with its center shifting westward, and vice versa. However, a negative correlation between the Changjiang River discharge and the ECSCE strength is shown. The ECSCE was strengthened after the abrupt global climate change affected by the interdecadal variation of the YSWC. 3) SVD analysis suggested a high correlation between the variation of the ECSCE in summer and the anomalous cyclonic atmospheric circulation over the ECS. Intensification of the cyclonic wind strengthens the ECSCE, and vice versa. 4) The cyclonic atmospheric circulation has dominant influence on the interannual variation of the ECSCE, and the influence of the ocean circulation takes the second in. The ECSCE was usually stronger in El Nino years affected by strong cyclonic circulation in the atmosphere. The variation in strength of the ECSCE resulted from the joint effect of both oceanic and atmospheric circulation.展开更多
Based on observed temperature data since the 1950s, long-term variability of the summer sharp thermocline in the Yellow Sea Cold Water Mass （YSCWM） and East China Sea Cold Eddy （ECSCE） areas is examined. Relations...Based on observed temperature data since the 1950s, long-term variability of the summer sharp thermocline in the Yellow Sea Cold Water Mass （YSCWM） and East China Sea Cold Eddy （ECSCE） areas is examined. Relationships between the thermocline and atmospheric and oceanic forcing were investigated using multiyear wind, Kuroshio discharge and air temperature data. Results show that： 1） In the YSCWM area, thermocline strength shows about 4-year and 16-year period oscillations. There is high correlation between summer thermocline strength and local atmospheric temperature in summer and the previous winter; 2） In the ECSCE area, interannual oscillation of thermocline strength with about a 4-year period （stronger in El Nifio years） is strongly correlated with that of local wind stress. A transition from weak to strong thermocline during the mid 1970s is consistent with a 1976/1977 climate shift and Kuroshio volume transport; 3） Long-term changes of the thermocline in both regions are mainly determined by deep layer water, especially on the decadal timescale. However, surface water can modify the thermocline on an interannual timescale in the YSCWM area.展开更多
文摘Based on more than 30 years observed sectional temperature data since the 1960s, and compared with multi-year wind and Changjiang (Yangtze) River discharge data, spatial-temporal variations of the East China Sea Cold Eddy (ECSCE) in summer was analyzed in relationship to ocean circulation and local atmospheric circulation. Empirical Orthogonal Function (EOF) and Singular Value Decomposition (SVD) analyses were applied to this study. The results show that: 1) The ECSCE in summer possesses significant interannual variabilities, which are directly associated with oceanic and atmospheric circulation anomaly. Main fluctuations demonstrate their falling in basically with El Nino events (interannual) and interdecadal variability. 2) The ECSCE in summer is closely related to the variation of the Yellow Sea Warm Current (YSWC) and the Changjiang River discharge. The stronger the YSWC, the more intensive the ECSCE with its center shifting westward, and vice versa. However, a negative correlation between the Changjiang River discharge and the ECSCE strength is shown. The ECSCE was strengthened after the abrupt global climate change affected by the interdecadal variation of the YSWC. 3) SVD analysis suggested a high correlation between the variation of the ECSCE in summer and the anomalous cyclonic atmospheric circulation over the ECS. Intensification of the cyclonic wind strengthens the ECSCE, and vice versa. 4) The cyclonic atmospheric circulation has dominant influence on the interannual variation of the ECSCE, and the influence of the ocean circulation takes the second in. The ECSCE was usually stronger in El Nino years affected by strong cyclonic circulation in the atmosphere. The variation in strength of the ECSCE resulted from the joint effect of both oceanic and atmospheric circulation.
基金Supported by the Knowledge Innovation Program of Chinese Academy of Sciences (No. KZCX2-YW-Q11-02)the Strategic Priority Research Program of Chinese Academy of Sciences (No. XDA05090404)the National Natural Science Foundation of China (No. 41106026)
文摘Based on observed temperature data since the 1950s, long-term variability of the summer sharp thermocline in the Yellow Sea Cold Water Mass （YSCWM） and East China Sea Cold Eddy （ECSCE） areas is examined. Relationships between the thermocline and atmospheric and oceanic forcing were investigated using multiyear wind, Kuroshio discharge and air temperature data. Results show that： 1） In the YSCWM area, thermocline strength shows about 4-year and 16-year period oscillations. There is high correlation between summer thermocline strength and local atmospheric temperature in summer and the previous winter; 2） In the ECSCE area, interannual oscillation of thermocline strength with about a 4-year period （stronger in El Nifio years） is strongly correlated with that of local wind stress. A transition from weak to strong thermocline during the mid 1970s is consistent with a 1976/1977 climate shift and Kuroshio volume transport; 3） Long-term changes of the thermocline in both regions are mainly determined by deep layer water, especially on the decadal timescale. However, surface water can modify the thermocline on an interannual timescale in the YSCWM area.
