As the world turns to the 21st century, new initiatives in marine scientific endeavors have been ... more As the world turns to the 21st century, new initiatives in marine scientific endeavors have been taken at several fronts. Many oceanographic disciplines have conducted workshops, reviewing their past advances and projecting their future development. Major international marine research programmes have updated their goals and research objectives, analyzing their past achievements and in light of the needs of the world humanity. China has also drafted a strategy study of the science and technology development for its long-term national plan, in response to the goal of “Building a Modest Prosperous Society in All Respects”. In this paper, we discuss the a new direction for China's research on marine ecosystems, based on considerations of the trends of the ocean sciences, the societal needs in view of China's economic development, and the integration steps taken by major international research programmes.
Hilbert-Huang Transform (HHT) is a newly developed powerful method for nonlinear and non-stationa... more Hilbert-Huang Transform (HHT) is a newly developed powerful method for nonlinear and non-stationary time series analysis. The empirical mode decomposition is the key part of HHT, while its algorithm was protected by NASA as a US patent, which limits the wide application among the scientific community. Two approaches, mirror periodic and extrema extending methods, have been developed for handling the end effects of empirical mode decomposition. The implementation of the HHT is realized in detail to widen the application. The detailed comparison of the results from two methods with that from Huang et al. (1998, 1999), and the comparison between two methods are presented. Generally, both methods reproduce faithful results as those of Huang et al. For mirror periodic method (MPM), the data are extended once forever. Ideally, it is a way for handling the end effects of the HHT, especially for the signal that has symmetric waveform. The extrema extending method (EEM) behaves as good as MPM, and it is better than MPM for the signal that has strong asymmetric waveform. However, it has to perform extrema envelope extending in every shifting process.
In spring of recent years,a large scale harmful algae bloom(HAB) of Prorocentrum donghaiense near... more In spring of recent years,a large scale harmful algae bloom(HAB) of Prorocentrum donghaiense nearly occurs annually in the end of April or beginning of May in the Zhejiang coastal and off Changjiang estuary region,however,it did't occur until the end of May of 2005.Temperature characteristic in the study area in early spring of 2005 and its influence on a large scale HAB of Prorocentrum donghaiense are analyzed on the basis of survey data carried out in spring of 2002-2005 and some related historical meteorologic data.The results show that water temperature in March 2005 is obviously lower than that of 15-year-averaged(1985-2001) in Zhejiang coastal sea,especially in nearshore region of Zhejiang coastal sea,compared to the same period of 2004,water temperature in early spring(early April) 2005 is about 2.6 ℃ lower.Special meteorologic conditions(the lowest air temperature in the past ten years and strong northern monsoon)and feeblish Taiwan Warm Current in winter of 2004/2005 are the main causes of low water temperature in investigated area.Low temperature characteristic may be main causative factor that a HAB of Prorocentrum donghaiense in spring 2005 occurred late which differ from that of Spring 2002—2004 in Zhejiang coastal sea.
The large scale circulation and mesoscale eddies have been mentioned in near 20 years. Many uniqu... more The large scale circulation and mesoscale eddies have been mentioned in near 20 years. Many unique characteristics have been revealed by oceanographers. The study of mesoscale eddies is more active than before with the applications of satellite altimeter and the development of numerical models. We will introduce the progresses in mesoscale eddies including observations and generation mechanisms in detail while large scale circulation presented briefly.
Based on the data obtained by field survey and experiments of the Zhujiang River Estuary during J... more Based on the data obtained by field survey and experiments of the Zhujiang River Estuary during July 17~28, 1999, the cycle, regeneration and restriction of N and P in water masses are studied. The results show that there is a large content of N in the Zhujiang River Estuary waters, and it belongs to a high N/P area in the world. With the water mass transported from river to sea, the speciation and concentration of N and P present a violent variation in the waters. Among others, there is new supply on the N, and the supplemental volume may be even larger than the absorbing capacity of plankton photosynthesis somewhere. Because of plankton absorbing, migration action of species variation and being intruded and being diluted by the seawater, the concentration of DIN was so constantly reduced and that the N/P was even lower than 16 off the Zhujiang River Estuary. The variation of concentration of PO~(3-)_4 become mirror image each other between the surface layer and the bottom layer water,which indicates that both the directions of biogeochemical action of P are contrary. The plankton absorbing is primary process in the surface layer, but the regeneration takes precedence in the middle layer and the bottom layer. Comparatively speaking, one point is the migration ratio of DIN is greater than DIP and the other is the turbidity (or light), P and N are the limit factors of the primary productivity in three areas (from the river gate to the maximum turbidity zone, middle waters of the estuary and off the estuary) respectively. The results of incubation show that the bloom of plankton lead to the considerabl decrease of concentration of DIN, but the concentration of PO~(3-)_4 is in a small scope vibration and keeps a more steady concentration level. It is inferred that the cycle and regeneration of P are more rapid than N, and the regeneration of P can direct supply primary product in euphotic and become a factor bringing to the plankton bloom in the waters, but the reason of the bloom passing away is the DIN being used up in the end. Through contrast study of biogeochemical cycle of N and P, similarities and differences of the process of cycle and regeneration between N and P are explicated, and infer potentiality of the denitrification action in the hypoxia area is inferred
Ocean sciences progressed rapidly in the 20th Century,especially during its secondhalf era.The cr... more Ocean sciences progressed rapidly in the 20th Century,especially during its secondhalf era.The critical function of the oceans in the earth system has been increasingly un-derstood.At the same time,the important role of the oceans in the sustainable develop-ment of our society has also been well recognized.Considering the potential problems fac-ing China in relation to climate,environment and resources,it is suggested that special at-tention should be paid to three areas in ocean science research in the early 21st Century.One is the role of the oceans in the climate variability at the seasonal,inter-annual and in-ter-decadal time scales.The other is the response of the coastal systems and marine e-cosystems to both natural environment variability and anthropogenic activities,includingthe global change.The third is on studies related to deep sea resources and paleo-environ-ments.In addition,it is also necessary to modernize ocean research vessels and to set upan ocean center devoted to deep sea research.
... Liu Xianbing and Su Jilan(Second Institute of Oceanography, SOA, Hangzhou 310012). A reduced ... more ... Liu Xianbing and Su Jilan(Second Institute of Oceanography, SOA, Hangzhou 310012). A reduced gravity numerical model is adopted to study the circulation in the South China ... 8, WANG Hui qun 1,2 ,YUAN Yao chu 1,2 ,LIU Yong gang 1,2 ,Zhou Ming yu 3 (1 Second Institute of ...
Recent studies on the circulation dynamics of the coastal oceans next to China are reviewed. Thes... more Recent studies on the circulation dynamics of the coastal oceans next to China are reviewed. These studies were based on extensive hydrographic surveys and some moored (mostly short term) current meter observations, as well as through numerical models. Although strong monsoonal winds, large buoyancy fluxes and active tidal mixing are all important in driving circulation in these oceans, interaction between the open ocean forcing and the unique topography of the coastal oceans seems be a major contributing factor to many of the outstanding feature found here north of 16°N.
Abstract The circulation in the East China Sea has been investigated by use of a single layer mod... more Abstract The circulation in the East China Sea has been investigated by use of a single layer model and a two-layer model. The aim is to obtain steady state solutions for the seasonal circulation patterns. Numerical results from these two models account for some aspects of the dynamics of the East China Sea.
There have been many numerical studies on the circulation in the East China Sea, including some d... more There have been many numerical studies on the circulation in the East China Sea, including some diagnostic computations (Yuan et al., 1986, 1987, 1988). Diagnostic models assume that the flow field is in a steady state and is compatible with the given wind field and the density distribution. This is a major shortcoming common to all diagnostic models. It is usually found, however, that difference between the result of diagnostic calculation and observed current velocity is not large. There have been many studies on prognostic models in the ocean circulation (Bryan and Cox, 1967; Sarkisyan, 1977). Shallow sea prognostic models were proposea lately by Hendershott and Rizzoli (1976) and by Shaw and Csanady (1983). In this paper, the winter circulation in the East China Sea is studied by a prognostic model similar to that of Shaw and Csanady (1983). The hydrographic data used are mostly the same as those of Yuan et al (1987).
Journal of Geophysical Research: Biogeosciences, 2019
The Bohai Sea to the west of the North Yellow Sea in the Northwest Pacific is a semienclosed shal... more The Bohai Sea to the west of the North Yellow Sea in the Northwest Pacific is a semienclosed shallow‐water marginal sea on a critical path of eutrophication and environmental degradation. To better understand the Bohai Sea metabolism‐induced summertime dissolved oxygen (DO) decline and acidification, eight field surveys were conducted between August 2011 and September 2017, investigating seasonal and interannual variations in DO and carbonate system parameters in the central Bohai Sea. The historically lowest Bohai Sea DO was recorded at 66 μmol O2/kg in subsurface waters in early September 2015. By comparing our data set with literature data obtained in the 1980s, 1990s, and 2000s, the emergence history of summertime hypoxia in this marginal sea was shown. Associated with the seasonal DO shortage, the metabolism‐enhanced CO2 accumulation in subsurface waters in summer resulted in critical aragonite saturation states of close to or even less than 1.5, threatening calcifiers with pot...
Hilbert-Huang Transform (HHT) is a newly developed powerful method for nonlinear and non-stationa... more Hilbert-Huang Transform (HHT) is a newly developed powerful method for nonlinear and non-stationary time series analysis. The empirical mode decomposition is the key part of HHT, while its algorithm was protected by NASA as a US patent, which limits the wide application among the scientific community. Two approaches, mirror periodic and extrema extending methods, have been developed for handling the end effects of empirical mode decomposition. The implementation of the HHT is realized in detail to widen the application. The detailed comparison of the results from two methods with that from Huang et al. (1998, 1999), and the comparison between two methods are presented. Generally, both methods reproduce faithful results as those of Huang et al. For mirror periodic method (MPM), the data are extended once forever. Ideally, it is a way for handling the end effects of the HHT, especially for the signal that has symmetric waveform. The extrema extending method (EEM) behaves as good as MPM, and it is better than MPM for the signal that has strong asymmetric waveform. However, it has to perform extrema envelope extending in every shifting process.
As the world turns to the 21st century, new initiatives in marine scientific endeavors have been ... more As the world turns to the 21st century, new initiatives in marine scientific endeavors have been taken at several fronts. Many oceanographic disciplines have conducted workshops, reviewing their past advances and projecting their future development. Major international marine research programmes have updated their goals and research objectives, analyzing their past achievements and in light of the needs of the world humanity. China has also drafted a strategy study of the science and technology development for its long-term national plan, in response to the goal of “Building a Modest Prosperous Society in All Respects”. In this paper, we discuss the a new direction for China's research on marine ecosystems, based on considerations of the trends of the ocean sciences, the societal needs in view of China's economic development, and the integration steps taken by major international research programmes.
Hilbert-Huang Transform (HHT) is a newly developed powerful method for nonlinear and non-stationa... more Hilbert-Huang Transform (HHT) is a newly developed powerful method for nonlinear and non-stationary time series analysis. The empirical mode decomposition is the key part of HHT, while its algorithm was protected by NASA as a US patent, which limits the wide application among the scientific community. Two approaches, mirror periodic and extrema extending methods, have been developed for handling the end effects of empirical mode decomposition. The implementation of the HHT is realized in detail to widen the application. The detailed comparison of the results from two methods with that from Huang et al. (1998, 1999), and the comparison between two methods are presented. Generally, both methods reproduce faithful results as those of Huang et al. For mirror periodic method (MPM), the data are extended once forever. Ideally, it is a way for handling the end effects of the HHT, especially for the signal that has symmetric waveform. The extrema extending method (EEM) behaves as good as MPM, and it is better than MPM for the signal that has strong asymmetric waveform. However, it has to perform extrema envelope extending in every shifting process.
In spring of recent years,a large scale harmful algae bloom(HAB) of Prorocentrum donghaiense near... more In spring of recent years,a large scale harmful algae bloom(HAB) of Prorocentrum donghaiense nearly occurs annually in the end of April or beginning of May in the Zhejiang coastal and off Changjiang estuary region,however,it did't occur until the end of May of 2005.Temperature characteristic in the study area in early spring of 2005 and its influence on a large scale HAB of Prorocentrum donghaiense are analyzed on the basis of survey data carried out in spring of 2002-2005 and some related historical meteorologic data.The results show that water temperature in March 2005 is obviously lower than that of 15-year-averaged(1985-2001) in Zhejiang coastal sea,especially in nearshore region of Zhejiang coastal sea,compared to the same period of 2004,water temperature in early spring(early April) 2005 is about 2.6 ℃ lower.Special meteorologic conditions(the lowest air temperature in the past ten years and strong northern monsoon)and feeblish Taiwan Warm Current in winter of 2004/2005 are the main causes of low water temperature in investigated area.Low temperature characteristic may be main causative factor that a HAB of Prorocentrum donghaiense in spring 2005 occurred late which differ from that of Spring 2002—2004 in Zhejiang coastal sea.
The large scale circulation and mesoscale eddies have been mentioned in near 20 years. Many uniqu... more The large scale circulation and mesoscale eddies have been mentioned in near 20 years. Many unique characteristics have been revealed by oceanographers. The study of mesoscale eddies is more active than before with the applications of satellite altimeter and the development of numerical models. We will introduce the progresses in mesoscale eddies including observations and generation mechanisms in detail while large scale circulation presented briefly.
Based on the data obtained by field survey and experiments of the Zhujiang River Estuary during J... more Based on the data obtained by field survey and experiments of the Zhujiang River Estuary during July 17~28, 1999, the cycle, regeneration and restriction of N and P in water masses are studied. The results show that there is a large content of N in the Zhujiang River Estuary waters, and it belongs to a high N/P area in the world. With the water mass transported from river to sea, the speciation and concentration of N and P present a violent variation in the waters. Among others, there is new supply on the N, and the supplemental volume may be even larger than the absorbing capacity of plankton photosynthesis somewhere. Because of plankton absorbing, migration action of species variation and being intruded and being diluted by the seawater, the concentration of DIN was so constantly reduced and that the N/P was even lower than 16 off the Zhujiang River Estuary. The variation of concentration of PO~(3-)_4 become mirror image each other between the surface layer and the bottom layer water,which indicates that both the directions of biogeochemical action of P are contrary. The plankton absorbing is primary process in the surface layer, but the regeneration takes precedence in the middle layer and the bottom layer. Comparatively speaking, one point is the migration ratio of DIN is greater than DIP and the other is the turbidity (or light), P and N are the limit factors of the primary productivity in three areas (from the river gate to the maximum turbidity zone, middle waters of the estuary and off the estuary) respectively. The results of incubation show that the bloom of plankton lead to the considerabl decrease of concentration of DIN, but the concentration of PO~(3-)_4 is in a small scope vibration and keeps a more steady concentration level. It is inferred that the cycle and regeneration of P are more rapid than N, and the regeneration of P can direct supply primary product in euphotic and become a factor bringing to the plankton bloom in the waters, but the reason of the bloom passing away is the DIN being used up in the end. Through contrast study of biogeochemical cycle of N and P, similarities and differences of the process of cycle and regeneration between N and P are explicated, and infer potentiality of the denitrification action in the hypoxia area is inferred
Ocean sciences progressed rapidly in the 20th Century,especially during its secondhalf era.The cr... more Ocean sciences progressed rapidly in the 20th Century,especially during its secondhalf era.The critical function of the oceans in the earth system has been increasingly un-derstood.At the same time,the important role of the oceans in the sustainable develop-ment of our society has also been well recognized.Considering the potential problems fac-ing China in relation to climate,environment and resources,it is suggested that special at-tention should be paid to three areas in ocean science research in the early 21st Century.One is the role of the oceans in the climate variability at the seasonal,inter-annual and in-ter-decadal time scales.The other is the response of the coastal systems and marine e-cosystems to both natural environment variability and anthropogenic activities,includingthe global change.The third is on studies related to deep sea resources and paleo-environ-ments.In addition,it is also necessary to modernize ocean research vessels and to set upan ocean center devoted to deep sea research.
... Liu Xianbing and Su Jilan(Second Institute of Oceanography, SOA, Hangzhou 310012). A reduced ... more ... Liu Xianbing and Su Jilan(Second Institute of Oceanography, SOA, Hangzhou 310012). A reduced gravity numerical model is adopted to study the circulation in the South China ... 8, WANG Hui qun 1,2 ,YUAN Yao chu 1,2 ,LIU Yong gang 1,2 ,Zhou Ming yu 3 (1 Second Institute of ...
Recent studies on the circulation dynamics of the coastal oceans next to China are reviewed. Thes... more Recent studies on the circulation dynamics of the coastal oceans next to China are reviewed. These studies were based on extensive hydrographic surveys and some moored (mostly short term) current meter observations, as well as through numerical models. Although strong monsoonal winds, large buoyancy fluxes and active tidal mixing are all important in driving circulation in these oceans, interaction between the open ocean forcing and the unique topography of the coastal oceans seems be a major contributing factor to many of the outstanding feature found here north of 16°N.
Abstract The circulation in the East China Sea has been investigated by use of a single layer mod... more Abstract The circulation in the East China Sea has been investigated by use of a single layer model and a two-layer model. The aim is to obtain steady state solutions for the seasonal circulation patterns. Numerical results from these two models account for some aspects of the dynamics of the East China Sea.
There have been many numerical studies on the circulation in the East China Sea, including some d... more There have been many numerical studies on the circulation in the East China Sea, including some diagnostic computations (Yuan et al., 1986, 1987, 1988). Diagnostic models assume that the flow field is in a steady state and is compatible with the given wind field and the density distribution. This is a major shortcoming common to all diagnostic models. It is usually found, however, that difference between the result of diagnostic calculation and observed current velocity is not large. There have been many studies on prognostic models in the ocean circulation (Bryan and Cox, 1967; Sarkisyan, 1977). Shallow sea prognostic models were proposea lately by Hendershott and Rizzoli (1976) and by Shaw and Csanady (1983). In this paper, the winter circulation in the East China Sea is studied by a prognostic model similar to that of Shaw and Csanady (1983). The hydrographic data used are mostly the same as those of Yuan et al (1987).
Journal of Geophysical Research: Biogeosciences, 2019
The Bohai Sea to the west of the North Yellow Sea in the Northwest Pacific is a semienclosed shal... more The Bohai Sea to the west of the North Yellow Sea in the Northwest Pacific is a semienclosed shallow‐water marginal sea on a critical path of eutrophication and environmental degradation. To better understand the Bohai Sea metabolism‐induced summertime dissolved oxygen (DO) decline and acidification, eight field surveys were conducted between August 2011 and September 2017, investigating seasonal and interannual variations in DO and carbonate system parameters in the central Bohai Sea. The historically lowest Bohai Sea DO was recorded at 66 μmol O2/kg in subsurface waters in early September 2015. By comparing our data set with literature data obtained in the 1980s, 1990s, and 2000s, the emergence history of summertime hypoxia in this marginal sea was shown. Associated with the seasonal DO shortage, the metabolism‐enhanced CO2 accumulation in subsurface waters in summer resulted in critical aragonite saturation states of close to or even less than 1.5, threatening calcifiers with pot...
Hilbert-Huang Transform (HHT) is a newly developed powerful method for nonlinear and non-stationa... more Hilbert-Huang Transform (HHT) is a newly developed powerful method for nonlinear and non-stationary time series analysis. The empirical mode decomposition is the key part of HHT, while its algorithm was protected by NASA as a US patent, which limits the wide application among the scientific community. Two approaches, mirror periodic and extrema extending methods, have been developed for handling the end effects of empirical mode decomposition. The implementation of the HHT is realized in detail to widen the application. The detailed comparison of the results from two methods with that from Huang et al. (1998, 1999), and the comparison between two methods are presented. Generally, both methods reproduce faithful results as those of Huang et al. For mirror periodic method (MPM), the data are extended once forever. Ideally, it is a way for handling the end effects of the HHT, especially for the signal that has symmetric waveform. The extrema extending method (EEM) behaves as good as MPM, and it is better than MPM for the signal that has strong asymmetric waveform. However, it has to perform extrema envelope extending in every shifting process.
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