The low-frequency variability of the North Equatorial Current （NEC） bifurcation during 1958 to 2001 was investigated with the Simple Ocean Data Assimilation （SODA） 2.0.2 dataset. In agreement with recent observati...The low-frequency variability of the North Equatorial Current （NEC） bifurcation during 1958 to 2001 was investigated with the Simple Ocean Data Assimilation （SODA） 2.0.2 dataset. In agreement with recent observations, the NEC bifurcation latitude （NBL） shifted northward as depth increases, from about 12.7°N near the surface to about 17.1°N at depths around 500 m for the annual average. This study reveals that the interannual variations of NBL, with five years period, mainly focused on the upper 500 m with amplitude increasing as depth increased. The NBL shifted southward in the past 40 years, which was more significant in the subsurface at more than -0.02°/a. The NBL manifests itself in the transports of NMK （NEC-Mindanao Current （MC）-Kuroshio） system in strong relationship with MC （0.7） and Kuroshio （-0.7）. The EOF analysis of meridional velocity off the Philippine coast shows that the first mode, explaining 62% of variance and 5 years period, was highly correlated with the southward shift of NBL with coefficient at about 0.75. The southward shift of NBL consists with the weakening of MC and strengthening of Kuroshio, which exhibited linear trends at -0.24Sv/a and 0.11Sv/a. Both interannual variation and trend of NBL were closely related to the variation of NMK system.展开更多
针对干旱半干旱区湖泊面积持续萎缩的问题,利用归一化水体指数(normalized difference water index,NDWI)等方法,分析达里诺尔湖泊面积的变化状况及变化的驱动力因素。1989—2020年达里诺尔湖湖泊面积呈下降态势,缩减了32.34 km^(2),200...针对干旱半干旱区湖泊面积持续萎缩的问题,利用归一化水体指数(normalized difference water index,NDWI)等方法,分析达里诺尔湖泊面积的变化状况及变化的驱动力因素。1989—2020年达里诺尔湖湖泊面积呈下降态势,缩减了32.34 km^(2),2000—2010年湖泊面积缩减幅度最大。研究表明,达里诺尔湖泊面积缩减的主要自然因素为多年来气温升高导致的蒸发量增大,以及降水量波动幅度较大,入湖水量不断减少,主要人为因素为耕地面积、牲畜存栏量增长以及工农业生产总值的快速增加,致使水资源消耗急剧增长和生态植被受到严重破坏,生态质量逐渐恶化。展开更多
基金supported by the National Natural Science Foundation of China under contract No.NSFC40890152the Knowledge Innovation Program of Chinese Academy of Sciences under contract No.KZCX2-YW-Q11-02
文摘The low-frequency variability of the North Equatorial Current （NEC） bifurcation during 1958 to 2001 was investigated with the Simple Ocean Data Assimilation （SODA） 2.0.2 dataset. In agreement with recent observations, the NEC bifurcation latitude （NBL） shifted northward as depth increases, from about 12.7°N near the surface to about 17.1°N at depths around 500 m for the annual average. This study reveals that the interannual variations of NBL, with five years period, mainly focused on the upper 500 m with amplitude increasing as depth increased. The NBL shifted southward in the past 40 years, which was more significant in the subsurface at more than -0.02°/a. The NBL manifests itself in the transports of NMK （NEC-Mindanao Current （MC）-Kuroshio） system in strong relationship with MC （0.7） and Kuroshio （-0.7）. The EOF analysis of meridional velocity off the Philippine coast shows that the first mode, explaining 62% of variance and 5 years period, was highly correlated with the southward shift of NBL with coefficient at about 0.75. The southward shift of NBL consists with the weakening of MC and strengthening of Kuroshio, which exhibited linear trends at -0.24Sv/a and 0.11Sv/a. Both interannual variation and trend of NBL were closely related to the variation of NMK system.
文摘针对干旱半干旱区湖泊面积持续萎缩的问题,利用归一化水体指数(normalized difference water index,NDWI)等方法,分析达里诺尔湖泊面积的变化状况及变化的驱动力因素。1989—2020年达里诺尔湖湖泊面积呈下降态势,缩减了32.34 km^(2),2000—2010年湖泊面积缩减幅度最大。研究表明,达里诺尔湖泊面积缩减的主要自然因素为多年来气温升高导致的蒸发量增大,以及降水量波动幅度较大,入湖水量不断减少,主要人为因素为耕地面积、牲畜存栏量增长以及工农业生产总值的快速增加,致使水资源消耗急剧增长和生态植被受到严重破坏,生态质量逐渐恶化。
