The basic structure and intraseasonal evolution of currents in the southeastern Andaman Sea was analyzed based on data collected in 2017 from two subsurface moorings(C1 and C5).Periodic variation in the upper ocean cu...The basic structure and intraseasonal evolution of currents in the southeastern Andaman Sea was analyzed based on data collected in 2017 from two subsurface moorings(C1 and C5).Periodic variation in the upper ocean currents of the Andaman Sea was investigated by combining observational and satellite data.Mooring observations show that rapid changes of current speed and direction occurred in May and June,with a significant increase in current velocity at the C1 mooring.In the second half of the year,southward flow dominated at the C1 mooring,and alternating northward and southward flows were evident at the C5 mooring during the same period but the northward flow prevailed in boreal winter.In addition,analysis of the power spectra of the upper currents revealed that the tidal period at both moorings is primarily semidiurnal with weaker energy than that of the low-frequency currents.The upper ocean currents at the C1 and C5 moorings exhibited intraseasonal variation of 30-60 d and 120 d,while the zonal current at the C1 mooring exhibited a notable period of approximately 180 d.Further analysis indicated that the variability of currents in the Andaman Sea is influenced primarily by equatorial Kelvin waves and Rossby wave packets.Moreover,our results suggest that equatorial Kelvin waves from the eastern Indian Ocean entered the Andaman Sea in the form of Wyrtki Jets and propagated primarily along two distinct pathways during the observation period.In addition to coastal boundary Kelvin waves,it was found that a branch of the Wyrtki Jet that directly enters the Andaman Sea and flows northward along the slope of the continental shelf,and reflected Rossby wave packets by topography.展开更多
The Bohai Sea is a shallow semi-enclosed inner sea with an average depth of 18 m and is located at the west of the northern Yellow Sea. The climatological circulation pattern in summer of the Bohai Sea is studied by u...The Bohai Sea is a shallow semi-enclosed inner sea with an average depth of 18 m and is located at the west of the northern Yellow Sea. The climatological circulation pattern in summer of the Bohai Sea is studied by using a wave-tide-circulation coupled model. The simulated temperature and the circulation agree with the observation well. The result shows that the circulation pattern of the Bohai Sea is jointly influenced by the tidal residual current, wind and baroclinic current. There exists an obvious density current along the temperature front from the west part of the Liaodong Bay to the offshore area of the Huanghe Estuary. In the Liaodong Bay there exists a clockwise gyre in the area north to the 40°N. While in the area south to the 40°N the circulation shows a two-gyre structure, the flow from the offshore area of the Huanghe Estuary to the Liaodong Bay splits into two branches in the area between 39°N and 40°N. The west branch turns into north-west and forms an anti-clockwise gyre with the south-westward density current off the west of the Liaodong Bay. The east branch turns to the east and forms a clockwise gyre with the flow along the east coast of the Liaodong Bay. The forming mechanism of the circulation is also discussed in this paper.展开更多
Using observational data of Argos satellite-tracked drifters from 1988 to 2012, we analyzed seasonal characteristics of the surface Kuroshio branch(KB) intrusion into the South China Sea(SCS). The analysis results are...Using observational data of Argos satellite-tracked drifters from 1988 to 2012, we analyzed seasonal characteristics of the surface Kuroshio branch(KB) intrusion into the South China Sea(SCS). The analysis results are as follows.The surface KB originates from the southern Balintang Channel(BLTC) and Babuyan Channel(BBYC). It begins in late September, reaches peak strength in November–December, and declines at the end of March. The mean speed of drifters along the KB path during their traverse of the Luzon Strait(LS) was 43% faster than during the two days before entering the LS for the flow originating from the southern BLTC, but there was a 24% increase in speed for the flow from the BBYC. The observations show that in winter, monthly-mean sea-level anomalies(SLAs) were positive southwest of Taiwan Island and extended to the northern LS. The SLAs were negative northwest of Luzon Island and extended to the southern LS, which acted like a pump, forcing a part of Kuroshio water westward into the SCS. The condition under which the KB forms was solved by a set of simplified motion equations. The results indicate that whether the KB can form depends upon the sea-level gradient at the central LS and region to the west, as well as the location, speed and direction of Kuroshio surface water when it enters the LS.展开更多
Although four species of odontocete and four species of baleen whale have been recorded in Prydz Bay,their vocalizations have been rarely investigated.Underwater vocalizations were recorded during March 2017 in Prydz ...Although four species of odontocete and four species of baleen whale have been recorded in Prydz Bay,their vocalizations have been rarely investigated.Underwater vocalizations were recorded during March 2017 in Prydz Bay,Antarctica.Bio-duck sounds,downsweeps,inverted“u”shape signals,whistles,pulsed sounds,and broadband clicks were recorded.Bio-duck sounds and downsweeps were associated with Antarctic minke whales(Balaenoptera bonaerensis)based on visual observations.Similarities between inverted“u”shape signals,biphonic calls,and clicks with vocalizations previously described for killer whales(Orcinus orca)lead us believe the presence of Antarctic killer whales.According to sound structures,signal characteristics,and recording location,Antarctic type C killer whales were the most probable candidates to produce these detected calls.These represent the fi rst detection of inverted“u”shape signals in Antarctic waters,and the fi rst report of Antarctic killer whale in Prydz Bay based on passive acoustic monitoring.The co-existence of Antarctic minke and killer whales may imply that minke whales can detect diff erences between the sounds of mammal-eating and fi sh-eating killer whales.Our descriptions of these underwater vocalizations contribute to the limited body of information regarding the distribution and acoustic behavior of cetaceans in Prydz Bay.展开更多
基金Supported by the Laoshan Laboratory(No.LSK 202203003)the National Key R&D Program of China(No.2022YFC3104100)。
文摘The basic structure and intraseasonal evolution of currents in the southeastern Andaman Sea was analyzed based on data collected in 2017 from two subsurface moorings(C1 and C5).Periodic variation in the upper ocean currents of the Andaman Sea was investigated by combining observational and satellite data.Mooring observations show that rapid changes of current speed and direction occurred in May and June,with a significant increase in current velocity at the C1 mooring.In the second half of the year,southward flow dominated at the C1 mooring,and alternating northward and southward flows were evident at the C5 mooring during the same period but the northward flow prevailed in boreal winter.In addition,analysis of the power spectra of the upper currents revealed that the tidal period at both moorings is primarily semidiurnal with weaker energy than that of the low-frequency currents.The upper ocean currents at the C1 and C5 moorings exhibited intraseasonal variation of 30-60 d and 120 d,while the zonal current at the C1 mooring exhibited a notable period of approximately 180 d.Further analysis indicated that the variability of currents in the Andaman Sea is influenced primarily by equatorial Kelvin waves and Rossby wave packets.Moreover,our results suggest that equatorial Kelvin waves from the eastern Indian Ocean entered the Andaman Sea in the form of Wyrtki Jets and propagated primarily along two distinct pathways during the observation period.In addition to coastal boundary Kelvin waves,it was found that a branch of the Wyrtki Jet that directly enters the Andaman Sea and flows northward along the slope of the continental shelf,and reflected Rossby wave packets by topography.
基金The National Key Research and Development Program of China under contract Nos 2017YFA0604101,2016YFB0201103,2017YFA0604104,2016YFC0503602,2016YFC1401403 and 2017YFC1404000the China Ocean Mineral Resources R&D Association program under contract No.DY135-E2-1-06+3 种基金the National Basic Research Program(973 Program)of China under contract No.2014CB745004the Ocean Forecast System project of the China-ASEAN Maritime Coopeartion Fundthe Strategic Priority Research Program of Chinese Academy of Sciences under contract No.XDA11020301the National Natural Science Foundation of China under contract No.41206025
文摘The Bohai Sea is a shallow semi-enclosed inner sea with an average depth of 18 m and is located at the west of the northern Yellow Sea. The climatological circulation pattern in summer of the Bohai Sea is studied by using a wave-tide-circulation coupled model. The simulated temperature and the circulation agree with the observation well. The result shows that the circulation pattern of the Bohai Sea is jointly influenced by the tidal residual current, wind and baroclinic current. There exists an obvious density current along the temperature front from the west part of the Liaodong Bay to the offshore area of the Huanghe Estuary. In the Liaodong Bay there exists a clockwise gyre in the area north to the 40°N. While in the area south to the 40°N the circulation shows a two-gyre structure, the flow from the offshore area of the Huanghe Estuary to the Liaodong Bay splits into two branches in the area between 39°N and 40°N. The west branch turns into north-west and forms an anti-clockwise gyre with the south-westward density current off the west of the Liaodong Bay. The east branch turns to the east and forms a clockwise gyre with the flow along the east coast of the Liaodong Bay. The forming mechanism of the circulation is also discussed in this paper.
基金The National Key Research and Development Program of China under contract Nos 2016YFC1401403,2016YFB0201103 and 2017YFA0604101the Strategic Priority Research Program of Chinese Academy of Sciences under contract No.XDA11020301+1 种基金the National Natural Science Foundation of China under contract No.41206025the China Ocean Mineral Resources R&D Association Program under contract No.DY135-E2-1-06
文摘Using observational data of Argos satellite-tracked drifters from 1988 to 2012, we analyzed seasonal characteristics of the surface Kuroshio branch(KB) intrusion into the South China Sea(SCS). The analysis results are as follows.The surface KB originates from the southern Balintang Channel(BLTC) and Babuyan Channel(BBYC). It begins in late September, reaches peak strength in November–December, and declines at the end of March. The mean speed of drifters along the KB path during their traverse of the Luzon Strait(LS) was 43% faster than during the two days before entering the LS for the flow originating from the southern BLTC, but there was a 24% increase in speed for the flow from the BBYC. The observations show that in winter, monthly-mean sea-level anomalies(SLAs) were positive southwest of Taiwan Island and extended to the northern LS. The SLAs were negative northwest of Luzon Island and extended to the southern LS, which acted like a pump, forcing a part of Kuroshio water westward into the SCS. The condition under which the KB forms was solved by a set of simplified motion equations. The results indicate that whether the KB can form depends upon the sea-level gradient at the central LS and region to the west, as well as the location, speed and direction of Kuroshio surface water when it enters the LS.
基金Supported by the National Natural Science Foundation of China(No.41906170)the Indian Ocean Ninety-east Ridge Ecosystem and Marine Environment Monitoring and Protection(No.DY135-E2-4)+1 种基金the Cooperation of Top Predators Observation in the Southern Ocean(No.QT4519003)the China-ASEAN Maritime Cooperation Fund。
文摘Although four species of odontocete and four species of baleen whale have been recorded in Prydz Bay,their vocalizations have been rarely investigated.Underwater vocalizations were recorded during March 2017 in Prydz Bay,Antarctica.Bio-duck sounds,downsweeps,inverted“u”shape signals,whistles,pulsed sounds,and broadband clicks were recorded.Bio-duck sounds and downsweeps were associated with Antarctic minke whales(Balaenoptera bonaerensis)based on visual observations.Similarities between inverted“u”shape signals,biphonic calls,and clicks with vocalizations previously described for killer whales(Orcinus orca)lead us believe the presence of Antarctic killer whales.According to sound structures,signal characteristics,and recording location,Antarctic type C killer whales were the most probable candidates to produce these detected calls.These represent the fi rst detection of inverted“u”shape signals in Antarctic waters,and the fi rst report of Antarctic killer whale in Prydz Bay based on passive acoustic monitoring.The co-existence of Antarctic minke and killer whales may imply that minke whales can detect diff erences between the sounds of mammal-eating and fi sh-eating killer whales.Our descriptions of these underwater vocalizations contribute to the limited body of information regarding the distribution and acoustic behavior of cetaceans in Prydz Bay.
