Analysis of tidal current and sea level has been made based on the observations from the summer of 2006 to the winter of 2007,respectively.The result indicates that a two-layer structure of residual current exists in ...Analysis of tidal current and sea level has been made based on the observations from the summer of 2006 to the winter of 2007,respectively.The result indicates that a two-layer structure of residual current exists in summer,with its upper layer going northwestward and the lower layer southeastward.In addition,some strong residuals exist in the neighboring depth of the pycnocline during the current period of astronomical tide.In winter,except some individual layersthe residual currents mostly direct to the northwest,from which we can see the fluctuation of abnormal sea-level and the appearance of associated current because of the changes of the wind field.The analysis of tidal ellipse indicates that the direction of the maximum semidiurnal component is clockwise from summer to winter,with an angle of 16-18.Moreover,in summer the semidiurnal component rotates with depth clockwise while the diurnal component counterclockwise.However,the vertical structure is almost homogeneous in winter.展开更多
-Some numerical experiments have been developed to explain dynamically the mechanism of the formation of the wintertime circulation in the Northern Huanghai Sea and the Bohai Sea. From the results of the numerical exp...-Some numerical experiments have been developed to explain dynamically the mechanism of the formation of the wintertime circulation in the Northern Huanghai Sea and the Bohai Sea. From the results of the numerical experiments with Coriolis parameter having positive and negative values respectively, it is found that the current pattern characterized by flowing into the Bohai Sea in the northern part of the Bohai Straits and flowing out of the Bohai Sea in the southern part of the Bohai Straits is controlled basically by the bottom topography with 'the deepness on the northern side and shallowness on the southern side'in the Bohai Straits, and is not related to Coriolis parameter having positive and negative values. It also shows that the Huanghai Warm Current regarded as the inllow condition passing through the in-ports at the water boundary of the numerical experiments only influences the region near the water boundary and the eastern region of the Northern Huanghai Sea. In addition, the mechanism of the formation of several mesoscale eddies and the influence of the bottom topography on the wintertime circulation in the basin have been discussed.展开更多
Based on the comprehensive collection of the field observed salinity of the Bohai Sea （BHS） and the northern Huanghai Sea （NHS） from the 1950s to the present, the patterns of 10-years-averaged salinity at the diff...Based on the comprehensive collection of the field observed salinity of the Bohai Sea （BHS） and the northern Huanghai Sea （NHS） from the 1950s to the present, the patterns of 10-years-averaged salinity at the different layers in the recent five decades （the 1950s, the 1960s, the 1970s, the 1980s and the 1990s） are obtained by the spatial-temporal interpolation technique with the scrupulous data quality control in this study. Then, by combining the spatial-temporal interpolation technique with successive correction method, the annual distributions of salinity both in the BHS and in the NHS are obtained as well. The data analyses indicate that the overall salinity in the BHS and the NHS increases from the 1960s till the present, with the increase of annual mean salinity of 0.04 psu from the 1950s, and the maximum increase rate of salinity is about 0.14 psu/a in the Bohai Bay. The high salinity tongue extended significantly from the NHS into the BHS. The intensified eastern wind field is related to the western intrusion of the NHS warm current, which probably leads to the moving forward of the high salinity water mass into the BHS. However, it is rather different from the salinity distribution characteristics between the 1950s and the 1960s. The extensive precipitation in the 1960s could lead to an increase in the discharge of the Huanghe River, which might result in the decrease of salinity in the BHS. But the salinity isoline of 32 in the NHS still extended significantly into the BHS in the 1960s. Since the 1980s, the patterns of salinity distribution have changed thoroughly. The salinity in the central area of the BHS was low, while the salinity in the Bohai Bay and the Liaodong Bay was higher than the other regions with its horizontal salinity gradient decreasing in the 1980s. The Empirical Orthogonal Function Analysis （EOF） is also conducted to study the interannual salinity variability of the BHS and the NHS. The correlation coefficient between the time coefficient series of the main mode and the Huanghe River discharge can reach-64.57%. It can be concluded that salinity variation of the BHS and the NHS has strong negative correlation with the Huanghe River discharge.展开更多
On the basis of hydrographic data and current measurement (the mooring system, vessel-mounted ADCP and toward ADCP) data obtained in June 1999, the circulations in the southern Huanghai Sea (HS) and northern East Chin...On the basis of hydrographic data and current measurement (the mooring system, vessel-mounted ADCP and toward ADCP) data obtained in June 1999, the circulations in the southern Huanghai Sea (HS) and northern East China Sea (ECS) are computed by using the modified inverse method. The Kuroshio flows northeastward through eastern part of the investigated region and has the main core at Section PN, a northward flow at the easternmost part of Section PN, a weaker anti-cyclonic eddy between these two northward flows, and a weak cyclonic eddy at the western part of Section PN. The above current structure is one type of the current structures at Section PN in ECS. The net northward volume transport (VT) of the Kuroshio and the offshore branch of Taiwan Warm Current (TWCOB) through Section PN is about 26.2 x 10(6) m(3)/s in June 1999. The VT of the inshore branch of Taiwan Warm Current (TWCIB) through the investigated region is about 0.4 x 10(6) m(3)/s. The Taiwan Warm Current (TWC) has much effect on the currents over the continental shelf. The Huanghai Sea Coastal Current (HSCC) flows southeastward and enters into the northwestern part of investigated region, and flows to turn cyclonically, and then it flows northeastward, due to the influences of the Taiwan Warm Current and topography. There is a cyclonic eddy south of Cheju Island where the Huanghai Sea Coastal Current flows to turn cyclonically. It has the feature of high dense and cold water. The uniform and cold water is occurred in the layer from about 30 m level to the bottom between Stations C306 and C311 at the northernmost Section C3. It is a southern part of the Huanghai Sea Cold Water Mass (HSCWM).展开更多
On the basis of the fact that the sharp thermocHne in the Bohai Sea and the northern Huanghai Sea is often distributed in the deep valley areas, it has been long thought that the reason of the formation of the sharp t...On the basis of the fact that the sharp thermocHne in the Bohai Sea and the northern Huanghai Sea is often distributed in the deep valley areas, it has been long thought that the reason of the formation of the sharp thermocHne is that the cold water can be easily kept in valleys. But recent investigations carried out in the southern Huanghai Sea in summer show that all of the sharp thermocHne areas were distributed in the shallow sloping-bottom areas but not in the deep valley areas. Only in autumn would the sharp thermoclines translate to the deep valley areas. In summer, they are characterized by shallow upper mixing layer and thin thickness in the southern Huanghai Sea. In addition to entrainment coming from lower boundary of upper mixing layer the entrainment from upper border of bottom homogeneous layer induced by tidal mixing also plays an important role in the growth and decay of thermoclines in these seas.展开更多
基金The Public Science and Technology Research Funds Projects of Ocean under contract Nos 200905001 and 201005019the State Basic Research Program of China under contract No.2005CB422303the National Natural Science Foundation of China under contract No.41006002
文摘Analysis of tidal current and sea level has been made based on the observations from the summer of 2006 to the winter of 2007,respectively.The result indicates that a two-layer structure of residual current exists in summer,with its upper layer going northwestward and the lower layer southeastward.In addition,some strong residuals exist in the neighboring depth of the pycnocline during the current period of astronomical tide.In winter,except some individual layersthe residual currents mostly direct to the northwest,from which we can see the fluctuation of abnormal sea-level and the appearance of associated current because of the changes of the wind field.The analysis of tidal ellipse indicates that the direction of the maximum semidiurnal component is clockwise from summer to winter,with an angle of 16-18.Moreover,in summer the semidiurnal component rotates with depth clockwise while the diurnal component counterclockwise.However,the vertical structure is almost homogeneous in winter.
文摘-Some numerical experiments have been developed to explain dynamically the mechanism of the formation of the wintertime circulation in the Northern Huanghai Sea and the Bohai Sea. From the results of the numerical experiments with Coriolis parameter having positive and negative values respectively, it is found that the current pattern characterized by flowing into the Bohai Sea in the northern part of the Bohai Straits and flowing out of the Bohai Sea in the southern part of the Bohai Straits is controlled basically by the bottom topography with 'the deepness on the northern side and shallowness on the southern side'in the Bohai Straits, and is not related to Coriolis parameter having positive and negative values. It also shows that the Huanghai Warm Current regarded as the inllow condition passing through the in-ports at the water boundary of the numerical experiments only influences the region near the water boundary and the eastern region of the Northern Huanghai Sea. In addition, the mechanism of the formation of several mesoscale eddies and the influence of the bottom topography on the wintertime circulation in the basin have been discussed.
基金The Hi-tech Research and Development Program(863 Program) of China under contract No2007AA09Z117comprehensive Survey and Assessment of China’s Coastal Sea Program(China ‘908’ Project) under contract No908-01-ST02China "973" Program under contract No 2005CB422302
文摘Based on the comprehensive collection of the field observed salinity of the Bohai Sea （BHS） and the northern Huanghai Sea （NHS） from the 1950s to the present, the patterns of 10-years-averaged salinity at the different layers in the recent five decades （the 1950s, the 1960s, the 1970s, the 1980s and the 1990s） are obtained by the spatial-temporal interpolation technique with the scrupulous data quality control in this study. Then, by combining the spatial-temporal interpolation technique with successive correction method, the annual distributions of salinity both in the BHS and in the NHS are obtained as well. The data analyses indicate that the overall salinity in the BHS and the NHS increases from the 1960s till the present, with the increase of annual mean salinity of 0.04 psu from the 1950s, and the maximum increase rate of salinity is about 0.14 psu/a in the Bohai Bay. The high salinity tongue extended significantly from the NHS into the BHS. The intensified eastern wind field is related to the western intrusion of the NHS warm current, which probably leads to the moving forward of the high salinity water mass into the BHS. However, it is rather different from the salinity distribution characteristics between the 1950s and the 1960s. The extensive precipitation in the 1960s could lead to an increase in the discharge of the Huanghe River, which might result in the decrease of salinity in the BHS. But the salinity isoline of 32 in the NHS still extended significantly into the BHS in the 1960s. Since the 1980s, the patterns of salinity distribution have changed thoroughly. The salinity in the central area of the BHS was low, while the salinity in the Bohai Bay and the Liaodong Bay was higher than the other regions with its horizontal salinity gradient decreasing in the 1980s. The Empirical Orthogonal Function Analysis （EOF） is also conducted to study the interannual salinity variability of the BHS and the NHS. The correlation coefficient between the time coefficient series of the main mode and the Huanghe River discharge can reach-64.57%. It can be concluded that salinity variation of the BHS and the NHS has strong negative correlation with the Huanghe River discharge.
基金National Natural Science Foundation of China under contract No. 40176007Major State Basic Research Program of China under contract No.G 1999043802.
文摘On the basis of hydrographic data and current measurement (the mooring system, vessel-mounted ADCP and toward ADCP) data obtained in June 1999, the circulations in the southern Huanghai Sea (HS) and northern East China Sea (ECS) are computed by using the modified inverse method. The Kuroshio flows northeastward through eastern part of the investigated region and has the main core at Section PN, a northward flow at the easternmost part of Section PN, a weaker anti-cyclonic eddy between these two northward flows, and a weak cyclonic eddy at the western part of Section PN. The above current structure is one type of the current structures at Section PN in ECS. The net northward volume transport (VT) of the Kuroshio and the offshore branch of Taiwan Warm Current (TWCOB) through Section PN is about 26.2 x 10(6) m(3)/s in June 1999. The VT of the inshore branch of Taiwan Warm Current (TWCIB) through the investigated region is about 0.4 x 10(6) m(3)/s. The Taiwan Warm Current (TWC) has much effect on the currents over the continental shelf. The Huanghai Sea Coastal Current (HSCC) flows southeastward and enters into the northwestern part of investigated region, and flows to turn cyclonically, and then it flows northeastward, due to the influences of the Taiwan Warm Current and topography. There is a cyclonic eddy south of Cheju Island where the Huanghai Sea Coastal Current flows to turn cyclonically. It has the feature of high dense and cold water. The uniform and cold water is occurred in the layer from about 30 m level to the bottom between Stations C306 and C311 at the northernmost Section C3. It is a southern part of the Huanghai Sea Cold Water Mass (HSCWM).
基金Contribution No.1234,Institute of Oceanology.Academia Sinica,Qingdao,China
文摘On the basis of the fact that the sharp thermocHne in the Bohai Sea and the northern Huanghai Sea is often distributed in the deep valley areas, it has been long thought that the reason of the formation of the sharp thermocHne is that the cold water can be easily kept in valleys. But recent investigations carried out in the southern Huanghai Sea in summer show that all of the sharp thermocHne areas were distributed in the shallow sloping-bottom areas but not in the deep valley areas. Only in autumn would the sharp thermoclines translate to the deep valley areas. In summer, they are characterized by shallow upper mixing layer and thin thickness in the southern Huanghai Sea. In addition to entrainment coming from lower boundary of upper mixing layer the entrainment from upper border of bottom homogeneous layer induced by tidal mixing also plays an important role in the growth and decay of thermoclines in these seas.
