We deployed two ADCP mooring systems west of the Luzon Strait in August 2008,and measured the upper ocean currents at high frequency.Two typhoons passed over the moorings during approximately one-month observation per...We deployed two ADCP mooring systems west of the Luzon Strait in August 2008,and measured the upper ocean currents at high frequency.Two typhoons passed over the moorings during approximately one-month observation period.Using ADCP observations,satellite wind and heat flux measurements,and high-resolution model assimilation products,we studied the response of the upper ocean to typhoons.The first typhoon,Nuri,passed over one of the moorings,resulting in strong Ekman divergence and significant surface cooling.The cooling of surface water lagged the typhoon wind forcing about one day and lasted about five days.The second typhoon,Sinlaku,moved northward east of the Luzon Strait,and did not directly impact currents near the observation regions.Sinlaku increased anomalous surface water transport exchange across the Luzon Strait,which modulated the surface layer current of the Kuroshio.展开更多
Internal solitary waves(ISWs) are frequently observed in the area between Dongsha Island(DI) and Taiwan Island. However, there have been few in-situ observations southwest of DI. To improve our knowledge of ISWs in th...Internal solitary waves(ISWs) are frequently observed in the area between Dongsha Island(DI) and Taiwan Island. However, there have been few in-situ observations southwest of DI. To improve our knowledge of ISWs in this area, we observed the ISWs over the continental shelf(115.4°E, 20.3°N) from Aug. 29 to Oct. 10, 2011 with temperature sensors and an acoustic Doppler current profiler(ADCP). The observations showed that the a fully developed ISW produced a current whose maximum westward velocity was 0.92 m/s and maximum northward velocity was 0.47 m/s. During the 41-day observation period the ISWs appeared for three periods with about 7-day gaps between each period. During each day, two types of ISWs were observed. The first type of wave arrived regularly diurnally at the same time each day, with a similar pattern to that of the type- a wave identified by Ramp et al.(2004). The second type arrived about 12 h after the first type and was delayed about 1 hour each day; this wave type was related to the type- b wave. Thus, our observations confirmed that both type- a and type- b waves can reach the area southwest of the DI. Moreover, the waves observed by the mooring propagated toward the directions of 270°–315° clockwise from true north, indicating obvious refraction from uneven topography around DI.展开更多
Seasonal and interannual variations of surface currents in the southern Taiwan Strait to the west of Taiwan Shoals were investigated by using measurements of high frequency(HF)ground wave radars from January 2006 to A...Seasonal and interannual variations of surface currents in the southern Taiwan Strait to the west of Taiwan Shoals were investigated by using measurements of high frequency(HF)ground wave radars from January 2006 to April 2009.The results demonstrate that surface currents in the water channel to the west of Taiwan Shoals are composed of a significant,seasonally fluctuating component and a relatively stable northward component.Forced by the East Asia monsoon,the annual variation of the surface longshore current is linearly correlated with the longshore wind.Behind the seasonal signal is a stable northward flow with speeds of O(10 cm/s).The observations also show that surface currents in the area are subject to distinct interannual variation,and the southward surface flow was more profound in winter 2007/2008 than in other winters.Observations from bottom-mounted ADCP also indicated that,in that winter,longshore currents in the west side of the Taiwan Strait are very different from the previous winter.The northward flow appeared much weaker,the currents were southward in most layers,and the interannual differences were observed throughout the water column.Hydrographic observations in the same period suggest that the large-scale southward intrusion of the Zhe-Min coastal water is the direct cause of the interannual difference.The enhancement of the East Asian monsoon during the 2007/2008 La Ni a event is considered as the main reason for the winter current anomalies in the study area.展开更多
基金Supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (Nos.KZCX1-YW-12-01KZCX2-YW-BR-04)+1 种基金the National Natural Science Foundation of China (Nos.40876007,40806006)the National High Technology Research and Development Program of China (863 Program) (No.2008AA09A402)
文摘We deployed two ADCP mooring systems west of the Luzon Strait in August 2008,and measured the upper ocean currents at high frequency.Two typhoons passed over the moorings during approximately one-month observation period.Using ADCP observations,satellite wind and heat flux measurements,and high-resolution model assimilation products,we studied the response of the upper ocean to typhoons.The first typhoon,Nuri,passed over one of the moorings,resulting in strong Ekman divergence and significant surface cooling.The cooling of surface water lagged the typhoon wind forcing about one day and lasted about five days.The second typhoon,Sinlaku,moved northward east of the Luzon Strait,and did not directly impact currents near the observation regions.Sinlaku increased anomalous surface water transport exchange across the Luzon Strait,which modulated the surface layer current of the Kuroshio.
基金Supported by the National Natural Science Foundation of China(Nos.41030855,U1133001,41376027)National High Technology Research and Development Program of China(863 Program)(No.2013AA09A502)
文摘Internal solitary waves(ISWs) are frequently observed in the area between Dongsha Island(DI) and Taiwan Island. However, there have been few in-situ observations southwest of DI. To improve our knowledge of ISWs in this area, we observed the ISWs over the continental shelf(115.4°E, 20.3°N) from Aug. 29 to Oct. 10, 2011 with temperature sensors and an acoustic Doppler current profiler(ADCP). The observations showed that the a fully developed ISW produced a current whose maximum westward velocity was 0.92 m/s and maximum northward velocity was 0.47 m/s. During the 41-day observation period the ISWs appeared for three periods with about 7-day gaps between each period. During each day, two types of ISWs were observed. The first type of wave arrived regularly diurnally at the same time each day, with a similar pattern to that of the type- a wave identified by Ramp et al.(2004). The second type arrived about 12 h after the first type and was delayed about 1 hour each day; this wave type was related to the type- b wave. Thus, our observations confirmed that both type- a and type- b waves can reach the area southwest of the DI. Moreover, the waves observed by the mooring propagated toward the directions of 270°–315° clockwise from true north, indicating obvious refraction from uneven topography around DI.
基金supported by the National Natural Science Foundation of China (40906052)Chinese Ministry of Science and Technology through the National Basic Research Program (2009CB421205)the Scientific Research Foundation of Third Institute of Oceanography, State Oceanic Administration (2009009 and 2009066)
文摘Seasonal and interannual variations of surface currents in the southern Taiwan Strait to the west of Taiwan Shoals were investigated by using measurements of high frequency(HF)ground wave radars from January 2006 to April 2009.The results demonstrate that surface currents in the water channel to the west of Taiwan Shoals are composed of a significant,seasonally fluctuating component and a relatively stable northward component.Forced by the East Asia monsoon,the annual variation of the surface longshore current is linearly correlated with the longshore wind.Behind the seasonal signal is a stable northward flow with speeds of O(10 cm/s).The observations also show that surface currents in the area are subject to distinct interannual variation,and the southward surface flow was more profound in winter 2007/2008 than in other winters.Observations from bottom-mounted ADCP also indicated that,in that winter,longshore currents in the west side of the Taiwan Strait are very different from the previous winter.The northward flow appeared much weaker,the currents were southward in most layers,and the interannual differences were observed throughout the water column.Hydrographic observations in the same period suggest that the large-scale southward intrusion of the Zhe-Min coastal water is the direct cause of the interannual difference.The enhancement of the East Asian monsoon during the 2007/2008 La Ni a event is considered as the main reason for the winter current anomalies in the study area.
