2014 Vol. 36, No. 1
Display Method:
2014, 36(1): .
Abstract:
2014, 36(1): 1-6.
doi: 10.3969/j.issn.0253-4193.2014.01.001
Abstract:
This article summarizes the related progress and issues about the oceanic 3-D temperature, salinity and current numerical simulation, including ocean model, data assimilation, the applications in the mesoscale numerical forecast and reanalysis, as well as the required supporting conditions. The related scientific issues in the wide range, mesoscale and submesoscale high-resolution ocean 3-D temperature, salinity and current numerical simulation are pointed out. The necessity of the developments of the oceanic in situ observations, such as the Argo profiles, and the remote observations, like the satellite altimetry data, as well as the supporting conditions, such as the high-performance computer simulation platform, is briefly explained. From these, the related issues which constrain our high-speed progress of the mesoscale numerical simulation are preliminarily discussed.
This article summarizes the related progress and issues about the oceanic 3-D temperature, salinity and current numerical simulation, including ocean model, data assimilation, the applications in the mesoscale numerical forecast and reanalysis, as well as the required supporting conditions. The related scientific issues in the wide range, mesoscale and submesoscale high-resolution ocean 3-D temperature, salinity and current numerical simulation are pointed out. The necessity of the developments of the oceanic in situ observations, such as the Argo profiles, and the remote observations, like the satellite altimetry data, as well as the supporting conditions, such as the high-performance computer simulation platform, is briefly explained. From these, the related issues which constrain our high-speed progress of the mesoscale numerical simulation are preliminarily discussed.
2014, 36(1): 7-19.
doi: 10.3969/j.issn.0253-4193.2014.01.002
Abstract:
The secondary circulation in the mixed layer of the upper ocean can bring the heat, momentum and material from the upper ocean to the subsurface which affects the vertical transport, exchange and mixing in this layer. The studies on the secondary circulation, including its formation mechanism and the interaction with other dynamic process, can enrich our understanding of the ocean upper layer. In this study, we use the linear stability theory to analyze stability of classical Ekman flow on the upper ocean, and present the idea that the instability of the Ekman flow can induced a new kind of secondary circulation. The space scales of this secondary circulation are closely related with the Reynolds number, decaying rate of Ekman flow and the ratio between the horizontal and the vertical turbulent viscosity coefficients etc, and have a wide range from tens of meters to several kilometers. For the secondary circulation of tens of meters, its vertical structure and the deflection angle between the axis of secondary circulation and the main flow are very similar to that of the Langmuir circulation, so this is a new explanation of the formation mechanism for Langmuir circulation. For the secondary circulation of kilometers, it may be responsible for the band structure of surface drifting macroalgae in the western Yellow Sea. In addition, the deflection angle between the axis of the secondary circulation and the main flow is affected by the coriolis force, in the northern hemisphere the secondary circulation turns to the left of the main slow, and to the right in the southern hemisphere.
The secondary circulation in the mixed layer of the upper ocean can bring the heat, momentum and material from the upper ocean to the subsurface which affects the vertical transport, exchange and mixing in this layer. The studies on the secondary circulation, including its formation mechanism and the interaction with other dynamic process, can enrich our understanding of the ocean upper layer. In this study, we use the linear stability theory to analyze stability of classical Ekman flow on the upper ocean, and present the idea that the instability of the Ekman flow can induced a new kind of secondary circulation. The space scales of this secondary circulation are closely related with the Reynolds number, decaying rate of Ekman flow and the ratio between the horizontal and the vertical turbulent viscosity coefficients etc, and have a wide range from tens of meters to several kilometers. For the secondary circulation of tens of meters, its vertical structure and the deflection angle between the axis of secondary circulation and the main flow are very similar to that of the Langmuir circulation, so this is a new explanation of the formation mechanism for Langmuir circulation. For the secondary circulation of kilometers, it may be responsible for the band structure of surface drifting macroalgae in the western Yellow Sea. In addition, the deflection angle between the axis of the secondary circulation and the main flow is affected by the coriolis force, in the northern hemisphere the secondary circulation turns to the left of the main slow, and to the right in the southern hemisphere.
2014, 36(1): 20-27.
doi: 10.3969/j.issn.0253-4193.2014.01.003
Abstract:
The Kuroshio subsurface water intrusion onto the East China Sea continental shelf is a year-round phenomenon to the northeast of Taiwan. However, the seasonal variation of the Kuroshio subsurface water intrusion still remains unclear. In this paper, the seasonal variation of Kuroshio intrusion onto the East China Sea continental shelf is investigated based on the CTD (conductivity temperature depth) data obtained from the four seasonal cruises of the East China Sea from 2009 to 2011. It is found that: the intrusion strengthens in late spring, strongest in summer, weakens in fall and becomes the weakest in winter. The depth of origin of the intruded Kuroshio subsurface water also varies with season. In addition, there exists significant short-term variability of the subsurface intrusion.
The Kuroshio subsurface water intrusion onto the East China Sea continental shelf is a year-round phenomenon to the northeast of Taiwan. However, the seasonal variation of the Kuroshio subsurface water intrusion still remains unclear. In this paper, the seasonal variation of Kuroshio intrusion onto the East China Sea continental shelf is investigated based on the CTD (conductivity temperature depth) data obtained from the four seasonal cruises of the East China Sea from 2009 to 2011. It is found that: the intrusion strengthens in late spring, strongest in summer, weakens in fall and becomes the weakest in winter. The depth of origin of the intruded Kuroshio subsurface water also varies with season. In addition, there exists significant short-term variability of the subsurface intrusion.
2014, 36(1): 28-37.
doi: 10.3969/j.issn.0253-4193.2014.01.004
Abstract:
On the basis of satellite altimeter data for 1993—2011, the seasonal signal, linear trend and low-frequency signal of the sea-level change in the East China Sea are investigated. The driving mechanisms of seasonal signal and low-frequency signal are analyzed by combining wind data, IshⅡ subsurface temperature and salinity data, sea surface temperature data and so on. The seasonal sea-level change mainly consists of annual signal, and occupies most of the sea-level change. The distribution of annual signal amplitude and phase is different in different regions. The main driving powers of seasonal signal in sea-level change are wind and thermal expansion, and the driving mechanisms are different in different regions and seasons. The leading role is also changing with the change of time and space. Besides, the seasonal signal is influenced by Kuroshio in the Kuroshio region. The mean linear trend of sea level is 3.28 mm/a and the trend is various in different places. The low-frequency signal of the sea-level change and the low-frequency signal of the steric sea-level change have notable relevance, and the correlation coefficient is 0.55. The low-frequency signal of the steric sea-level change and the low-frequency signal of SOI have certain relevance, and the max correlation coefficient is 0.3. ENSO can affect the steric sea-level change through the atmospheric circulation and the Kuroshio, and the steric sea-level change then can influence the sea-level change in the East China Sea. Therefore, ENSO can influence sea-level change through the steric-sea level change.
On the basis of satellite altimeter data for 1993—2011, the seasonal signal, linear trend and low-frequency signal of the sea-level change in the East China Sea are investigated. The driving mechanisms of seasonal signal and low-frequency signal are analyzed by combining wind data, IshⅡ subsurface temperature and salinity data, sea surface temperature data and so on. The seasonal sea-level change mainly consists of annual signal, and occupies most of the sea-level change. The distribution of annual signal amplitude and phase is different in different regions. The main driving powers of seasonal signal in sea-level change are wind and thermal expansion, and the driving mechanisms are different in different regions and seasons. The leading role is also changing with the change of time and space. Besides, the seasonal signal is influenced by Kuroshio in the Kuroshio region. The mean linear trend of sea level is 3.28 mm/a and the trend is various in different places. The low-frequency signal of the sea-level change and the low-frequency signal of the steric sea-level change have notable relevance, and the correlation coefficient is 0.55. The low-frequency signal of the steric sea-level change and the low-frequency signal of SOI have certain relevance, and the max correlation coefficient is 0.3. ENSO can affect the steric sea-level change through the atmospheric circulation and the Kuroshio, and the steric sea-level change then can influence the sea-level change in the East China Sea. Therefore, ENSO can influence sea-level change through the steric-sea level change.
2014, 36(1): 38-47.
doi: 10.3969/j.issn.0253-4193.2014.01.005
Abstract:
The simulation abilities of 32 CMIP5 (Coupled Model Intercomparison Project Phase 5) climate models to the historical sea surface temperature (SST) in the South China Sea are evaluated by verifying its long-term linear trend and standard deviation. The projections of the SST for the 21st century under different RCP (Representative Concentration Pathway) emission scenarios are analyzed. The results show that most of the models can well reproduce the primary characteristic and change of the historical SST in the South China Sea. However,the simulations of the historical SST are unsatisfactory for 15 climate models. These models are excluded in evaluating the RCP forecasts for minimizing the uncertainty of the forecast results,while their effects to the multi-model ensemble mean are not so significant. Other models show that the SST in the South China Sea will be significant warming in the 21st century,whose linear trends of the multi-model ensemble mean are 0.42,1.50 and 3.30℃/(100 a) under RCP26,RCP45,and RCP85 scenarios,respectively. The changes of these trends are relatively small in space,but not with time. The warming in the early 21st century is significantly stronger than that in the late 21st century under RCP26 and RCP45scenarios,while the opposite under RCP85 scenario.
The simulation abilities of 32 CMIP5 (Coupled Model Intercomparison Project Phase 5) climate models to the historical sea surface temperature (SST) in the South China Sea are evaluated by verifying its long-term linear trend and standard deviation. The projections of the SST for the 21st century under different RCP (Representative Concentration Pathway) emission scenarios are analyzed. The results show that most of the models can well reproduce the primary characteristic and change of the historical SST in the South China Sea. However,the simulations of the historical SST are unsatisfactory for 15 climate models. These models are excluded in evaluating the RCP forecasts for minimizing the uncertainty of the forecast results,while their effects to the multi-model ensemble mean are not so significant. Other models show that the SST in the South China Sea will be significant warming in the 21st century,whose linear trends of the multi-model ensemble mean are 0.42,1.50 and 3.30℃/(100 a) under RCP26,RCP45,and RCP85 scenarios,respectively. The changes of these trends are relatively small in space,but not with time. The warming in the early 21st century is significantly stronger than that in the late 21st century under RCP26 and RCP45scenarios,while the opposite under RCP85 scenario.
2014, 36(1): 48-55.
doi: 10.3969/j.issn.0253-4193.2014.01.006
Abstract:
The water age concept is applied to the Changjiang Estuary to quantitatively study the influences of tide and river discharge on the transport timescale under the long-term mean flow discharge condition based on numerical model simulations. The study provides the spatial structure of the mean transport timescale of freshwater in the estuary. The result shows that it takes approximately 24 days for the water to be transported from the Xuliujing to the mouth of the Changjiang Estuary(122.5°E). The transport timescale is dominated by the river discharge on the upstream portion of the estuary prior to the bifurcation between the South Channel and the North Channel. The mean transport time is 8 day in this area. From the bifurcation location to the middle portion of the North Passage, both the river runoff and tide affect the transport timescale, and the transport time is about 16 days in this area, indicating that the transport rate is slower than both the upstream and the downstream. The stratification impact on transport timescale is evident in the Changjiang Estuary. A 6 day difference of transport timescale between the surface and bottom is observed. The numerical experiment results indicate that the tide is the key forcing affecting the transport timescale in the estuary, which increase exchange rate and decreased the transport time in the Changjiang Estuary. This study illustrates that the water age concept can not only be used to investigate the transport of water, but also provide the underlying hydrodynamics for the transport of pollutants and suspended sediment in the Changjiang Estuary.
The water age concept is applied to the Changjiang Estuary to quantitatively study the influences of tide and river discharge on the transport timescale under the long-term mean flow discharge condition based on numerical model simulations. The study provides the spatial structure of the mean transport timescale of freshwater in the estuary. The result shows that it takes approximately 24 days for the water to be transported from the Xuliujing to the mouth of the Changjiang Estuary(122.5°E). The transport timescale is dominated by the river discharge on the upstream portion of the estuary prior to the bifurcation between the South Channel and the North Channel. The mean transport time is 8 day in this area. From the bifurcation location to the middle portion of the North Passage, both the river runoff and tide affect the transport timescale, and the transport time is about 16 days in this area, indicating that the transport rate is slower than both the upstream and the downstream. The stratification impact on transport timescale is evident in the Changjiang Estuary. A 6 day difference of transport timescale between the surface and bottom is observed. The numerical experiment results indicate that the tide is the key forcing affecting the transport timescale in the estuary, which increase exchange rate and decreased the transport time in the Changjiang Estuary. This study illustrates that the water age concept can not only be used to investigate the transport of water, but also provide the underlying hydrodynamics for the transport of pollutants and suspended sediment in the Changjiang Estuary.
2014, 36(1): 56-64.
doi: 10.3969/j.issn.0253-4193.2014.01.007
Abstract:
A numerical simulation study on potential earthquake-generated tsunami is carried out in the paper for Bohai Sea based on comprehensive consideration of the tsunamigenic conditions, topography feature, geological structure, seismological features and historical records about earthquake and tsunami. Tsunamigenic zones and possibility of tsunami hazards in Bohai Sea were analyzed and discussed respectively. Several local tsunamis were simulated by tsunami numerical model which was triggered by historical subduction earthquakes which have magnitudes larger than Mw7.0 in Bohai Sea. The tsunami model adopted adaptive mesh refinement technology based on Quadtree principle. The contradiction between the local resolution and the computational efficiency was resolved by using adaptive mesh. Numerical computation including seabed deformation,tsunami propagating over deep and shallow water. Potential tsunami induced by a hypothetical earthquake with Mw7.8 was simulated using tsunami numerical model in this paper. Its propagation scenario and wave characteristics were analyzed around Bohai Sea region. The impact of potential tsunami on Bohai Sea coasts and northern Huanghai Sea coasts was discussed quantitatively ground on the numerical calculation result. A preliminary tsunami hazards for Bohai Sea were classified. The study presented in this paper will serve as the technological support to the tsunami hazards analysis and the technology research of tsunami early warning.
A numerical simulation study on potential earthquake-generated tsunami is carried out in the paper for Bohai Sea based on comprehensive consideration of the tsunamigenic conditions, topography feature, geological structure, seismological features and historical records about earthquake and tsunami. Tsunamigenic zones and possibility of tsunami hazards in Bohai Sea were analyzed and discussed respectively. Several local tsunamis were simulated by tsunami numerical model which was triggered by historical subduction earthquakes which have magnitudes larger than Mw7.0 in Bohai Sea. The tsunami model adopted adaptive mesh refinement technology based on Quadtree principle. The contradiction between the local resolution and the computational efficiency was resolved by using adaptive mesh. Numerical computation including seabed deformation,tsunami propagating over deep and shallow water. Potential tsunami induced by a hypothetical earthquake with Mw7.8 was simulated using tsunami numerical model in this paper. Its propagation scenario and wave characteristics were analyzed around Bohai Sea region. The impact of potential tsunami on Bohai Sea coasts and northern Huanghai Sea coasts was discussed quantitatively ground on the numerical calculation result. A preliminary tsunami hazards for Bohai Sea were classified. The study presented in this paper will serve as the technological support to the tsunami hazards analysis and the technology research of tsunami early warning.
2014, 36(1): 65-71.
doi: 10.3969/j.issn.0253-4193.2014.01.008
Abstract:
Double-diffusive staircases are located between the cold, fresh upper water and the warm, salty Atlantic Water in the Arctic Ocean. Based on the data of Moored Profiler, Ice-Tethered Profilers,and Microstructure Profiler, heat flux across the staircases were analyzed. Three staircases in Moored profiles were traced to study the temporal evolution of hydrographical properties of the staircases. Heat flux differences between the upper and lower interfaces were correlated with heat variance of the mixed layer. With the data of Microstructure Profiler, heat flux across the interface was estimated by the assumption of the molecular heat conduction being dominated. When the maximum potential temperature gradient was taken, the result was close to that based on the empirical formula of heat flux. Therefore, it was confirmed that empirical formula of heat flux obtained from the laboratory experiments can be applied in the diffusive convection of the Arcitc Ocean.
Double-diffusive staircases are located between the cold, fresh upper water and the warm, salty Atlantic Water in the Arctic Ocean. Based on the data of Moored Profiler, Ice-Tethered Profilers,and Microstructure Profiler, heat flux across the staircases were analyzed. Three staircases in Moored profiles were traced to study the temporal evolution of hydrographical properties of the staircases. Heat flux differences between the upper and lower interfaces were correlated with heat variance of the mixed layer. With the data of Microstructure Profiler, heat flux across the interface was estimated by the assumption of the molecular heat conduction being dominated. When the maximum potential temperature gradient was taken, the result was close to that based on the empirical formula of heat flux. Therefore, it was confirmed that empirical formula of heat flux obtained from the laboratory experiments can be applied in the diffusive convection of the Arcitc Ocean.
2014, 36(1): 72-85.
doi: 10.3969/j.issn.0253-4193.2014.01.009
Abstract:
The air-sea coupled features are investigated associated with Eastern Pacific (EP) La Niña and Central Pacific (CP) La Niña during seasonal evolution, by using the monthly sea surface temperature from HadISST, subsurface sea temperature from SODA, and reanalysis data from NCEP/NCAR. For EP La Niña, the sea surface temperature anomalies (SSTA) occur over South American coast in developing summer and then are displaced westward. The negative SSTA center covers the eastern equatorial Pacific during the mature phase. Nevertheless, no significant propagation of SSTA is observed for the CP La Niña and its SSTA center maintains at around 160°W. The CP La Niña-SSTA are more intensive and persist longer compared to the EP La Niña. Tropical atmosphere responses are different for two types of La Niña. The CP La Niña is featured by a stronger intensity, a larger extent, and a slightly westward displacement in moist divergence compared to the EP La Niña. As a response to the two types of La Niña, height anomalies are both weak in developing summer and autumn. A negative Pacific-North America (PNA) pattern tends to be dominant during La Niña winters. However, their intensity and location differ from each other. Almost opposing North Atlantic Oscillation (NAO)-like atmospheric anomalies occur during the EP and CP La Niña winters, which may cause very different regional climate anomalies.
The air-sea coupled features are investigated associated with Eastern Pacific (EP) La Niña and Central Pacific (CP) La Niña during seasonal evolution, by using the monthly sea surface temperature from HadISST, subsurface sea temperature from SODA, and reanalysis data from NCEP/NCAR. For EP La Niña, the sea surface temperature anomalies (SSTA) occur over South American coast in developing summer and then are displaced westward. The negative SSTA center covers the eastern equatorial Pacific during the mature phase. Nevertheless, no significant propagation of SSTA is observed for the CP La Niña and its SSTA center maintains at around 160°W. The CP La Niña-SSTA are more intensive and persist longer compared to the EP La Niña. Tropical atmosphere responses are different for two types of La Niña. The CP La Niña is featured by a stronger intensity, a larger extent, and a slightly westward displacement in moist divergence compared to the EP La Niña. As a response to the two types of La Niña, height anomalies are both weak in developing summer and autumn. A negative Pacific-North America (PNA) pattern tends to be dominant during La Niña winters. However, their intensity and location differ from each other. Almost opposing North Atlantic Oscillation (NAO)-like atmospheric anomalies occur during the EP and CP La Niña winters, which may cause very different regional climate anomalies.
2014, 36(1): 86-97.
doi: 10.3969/j.issn.0253-4193.2014.01.010
Abstract:
In this paper, the impact of the preceding-summer heat content over western Pacific warm pool on Spring Persistent Rain was analyzed based on the GODAS monthly mean sea temperature, China 753 stations precipitation and NCEP/NCAR daily reanalysis data. Possible process and mechanism were studied through anomalous circulation in upper and low level. Major results were: (1) Heat content over key region(9°~16°N,150°~166°E) in preceding-summer was anti-correlated with the intensity of SPR. The significant low heat content in preceding-summer strongly indicated surplus rainfall in spring. (2)Difference field (rainy years minus drought years) in spring was consistent with spring circulation regressed by the heat content(opposite sign) in preceding-summer over warm pool. Direct causes of surplus rainfall were warm and wet southwest airflow in the low level, which located in northwest of the anomalous Philippine Sea anticyclone, and the pumping effect over Jiang Nan in upper level. (3)The anomalous low heat content over key region in preceding-summer induced low-level anomalous anticyclone in northwest, which persisted to current spring from preceding-summer. In spring, driven by the anomalous anticyclone, powerful southwest flow carried abundant moisture to Jiang Nan. Meanwhile, anomalous cyclone of upper level over mainland of China was stimulated and lasted from preceding-autumn to current spring. The anomalous cyclone led to southward replacement of westerly jet axis and formation of the abnormal divergence center with intense pumping effect in the upper level, hence resulting in surplus rainfall in spring. Process of abnormally less rainfall in spring caused by anomalous high heat content in pre-summer was on the contrary.
In this paper, the impact of the preceding-summer heat content over western Pacific warm pool on Spring Persistent Rain was analyzed based on the GODAS monthly mean sea temperature, China 753 stations precipitation and NCEP/NCAR daily reanalysis data. Possible process and mechanism were studied through anomalous circulation in upper and low level. Major results were: (1) Heat content over key region(9°~16°N,150°~166°E) in preceding-summer was anti-correlated with the intensity of SPR. The significant low heat content in preceding-summer strongly indicated surplus rainfall in spring. (2)Difference field (rainy years minus drought years) in spring was consistent with spring circulation regressed by the heat content(opposite sign) in preceding-summer over warm pool. Direct causes of surplus rainfall were warm and wet southwest airflow in the low level, which located in northwest of the anomalous Philippine Sea anticyclone, and the pumping effect over Jiang Nan in upper level. (3)The anomalous low heat content over key region in preceding-summer induced low-level anomalous anticyclone in northwest, which persisted to current spring from preceding-summer. In spring, driven by the anomalous anticyclone, powerful southwest flow carried abundant moisture to Jiang Nan. Meanwhile, anomalous cyclone of upper level over mainland of China was stimulated and lasted from preceding-autumn to current spring. The anomalous cyclone led to southward replacement of westerly jet axis and formation of the abnormal divergence center with intense pumping effect in the upper level, hence resulting in surplus rainfall in spring. Process of abnormally less rainfall in spring caused by anomalous high heat content in pre-summer was on the contrary.
2014, 36(1): 98-108.
doi: 10.3969/j.issn.0253-4193.2014.01.011
Abstract:
Using the CMA-STI Best Track Dataset and NCEP/NCAR reanalysis data,super typhoon Saomai(0608) is diagnosed during its rapid intensification stage over the coastal waters of China. The results show that the total vorticity budget begins to increase in the upper troposphere,and then it increases in the mid-level and gradually stretches to the lower troposphere. When the upper vorticity decreases and the middle and lower vorticity both increase,Saomai becoms rapid intensification. The vorticity advection term contributes greatest to the rapid-intensification of Saomai in the mid and lower troposphere,which is closely linked with tropical cyclone Bopha(0609). Further exploring the advanced research meso-scale model WRF_ARW V 3.3 to study,the simulation results show that the intensity rapid change over the coastal waters of Saomai is closely related to the entrainment of vorticity belt into its circulation from the remnant of typhoon Bopha (0609) which is neighboring to Saomai.
Using the CMA-STI Best Track Dataset and NCEP/NCAR reanalysis data,super typhoon Saomai(0608) is diagnosed during its rapid intensification stage over the coastal waters of China. The results show that the total vorticity budget begins to increase in the upper troposphere,and then it increases in the mid-level and gradually stretches to the lower troposphere. When the upper vorticity decreases and the middle and lower vorticity both increase,Saomai becoms rapid intensification. The vorticity advection term contributes greatest to the rapid-intensification of Saomai in the mid and lower troposphere,which is closely linked with tropical cyclone Bopha(0609). Further exploring the advanced research meso-scale model WRF_ARW V 3.3 to study,the simulation results show that the intensity rapid change over the coastal waters of Saomai is closely related to the entrainment of vorticity belt into its circulation from the remnant of typhoon Bopha (0609) which is neighboring to Saomai.
2014, 36(1): 109-118.
doi: 10.3969/j.issn.0253-4193.2014.01.012
Abstract:
Three-dimensional reconstruction of temperature and salinity based on Optimal interpolation requires correct estimation of the background error covariance and the error correlation scale is determined by baroclinic Rossby radius of deformation. According this issue,they proposed a research scheme of optimizing the correlation length-scale by baroclinic Rossby radius of deformation using the newest high resolution regional climatological data. In this paper,they compared the different results calculated by homogenization correlation scale scheme,the French ISAS scale scheme and the radius of deformation scheme. The results showed that: the RMSE of homogenization correlation scales scheme was much smaller than that of ISAS scheme,but pattern of temperature was too smooth and appears unreasonable extremes,so it could not describe some of the important physical phenomena; when the error correlation length was taken as 2 times the radius of deformation,the RMSE at every level was relatively smaller; in addition,the temperature calculated by the new scales scheme determined by the radius of deformation could better describe the three-dimensional structure of temperature affected by both Kuroshio and vortex field in Shikoku basin. As the actual physical processes in the ocean were different,the settings of optimal scales scheme was different in different layers.
Three-dimensional reconstruction of temperature and salinity based on Optimal interpolation requires correct estimation of the background error covariance and the error correlation scale is determined by baroclinic Rossby radius of deformation. According this issue,they proposed a research scheme of optimizing the correlation length-scale by baroclinic Rossby radius of deformation using the newest high resolution regional climatological data. In this paper,they compared the different results calculated by homogenization correlation scale scheme,the French ISAS scale scheme and the radius of deformation scheme. The results showed that: the RMSE of homogenization correlation scales scheme was much smaller than that of ISAS scheme,but pattern of temperature was too smooth and appears unreasonable extremes,so it could not describe some of the important physical phenomena; when the error correlation length was taken as 2 times the radius of deformation,the RMSE at every level was relatively smaller; in addition,the temperature calculated by the new scales scheme determined by the radius of deformation could better describe the three-dimensional structure of temperature affected by both Kuroshio and vortex field in Shikoku basin. As the actual physical processes in the ocean were different,the settings of optimal scales scheme was different in different layers.
2014, 36(1): 119-125.
doi: 10.3969/j.issn.0253-4193.2014.01.013
Abstract:
Based on several foreign commercial software in the field of sub-bottom profile's data acquisition which has been widely used in our country,the article analyzes and discusses their several basic defects in data acquisition and storage,such as severe GPS's lag,the change of high-energy reflection events phase and polar,data acquisition and storage in deep water,etc. In ordered to resolve the defects mentioned above,Oriented ChirpⅢ device developed by American Benthos Corporation,the author independently developed the Chinese data acquisition software. By this software,the author analyzes the defects within foreign commercial software and put forward the reliable solutions. By actual testing and comparing the data playback,developed software is proved to successfully solve the defects existed in foreign commercial software.
Based on several foreign commercial software in the field of sub-bottom profile's data acquisition which has been widely used in our country,the article analyzes and discusses their several basic defects in data acquisition and storage,such as severe GPS's lag,the change of high-energy reflection events phase and polar,data acquisition and storage in deep water,etc. In ordered to resolve the defects mentioned above,Oriented ChirpⅢ device developed by American Benthos Corporation,the author independently developed the Chinese data acquisition software. By this software,the author analyzes the defects within foreign commercial software and put forward the reliable solutions. By actual testing and comparing the data playback,developed software is proved to successfully solve the defects existed in foreign commercial software.
2014, 36(1): 126-130.
doi: 10.3969/j.issn.0253-4193.2014.01.014
Abstract:
Based on a well-verified three-dimensional tidal flow mathematical model, the Xiangshan Harbour is divieled into seven areas, seven different dissolved conservative materials are used as tracers, an advection-diffusion water exchange numerical model is established, and an associated matrix method is applied to describing water exchange characteristics between districts, and between these districts and the sea. The concentration distribution of different tracers, is used to calculate water exchange matrixes of the 15th, 30th, 45th,60th and 80th day. According to the water exchange matrix in each moment, among the seven regions of the Xiangshan Harbour, exchanging with the outside water in Region I is the fastest, which has an exchange rate of 85% in 15 d, while the slowest Region Ⅶ only reaches about 10% after the same duration. In Region Ⅲ (the Xihu Inlet), Region Ⅵ (the Huangdun Inlet) and Region Ⅶ (the Tiegang Inlet)the water exchange speed is slow between these regions and the outside water,but is still significantly faster than other regions. The fastest is in Region Ⅵ, in which the original water accounts for 1.5% on the 15th day, and 0.3% on the 60th day. And the slowest is in Huangdun Inlet Ⅳ, in which the original water accounts for 22.7% on the 15th day, and 4.4% on the 60th day. Furthermore, the matrix suggests that water exchanges between the Xihu Inlet and the Huangdun Inlet and three inner inlets are very weak.
Based on a well-verified three-dimensional tidal flow mathematical model, the Xiangshan Harbour is divieled into seven areas, seven different dissolved conservative materials are used as tracers, an advection-diffusion water exchange numerical model is established, and an associated matrix method is applied to describing water exchange characteristics between districts, and between these districts and the sea. The concentration distribution of different tracers, is used to calculate water exchange matrixes of the 15th, 30th, 45th,60th and 80th day. According to the water exchange matrix in each moment, among the seven regions of the Xiangshan Harbour, exchanging with the outside water in Region I is the fastest, which has an exchange rate of 85% in 15 d, while the slowest Region Ⅶ only reaches about 10% after the same duration. In Region Ⅲ (the Xihu Inlet), Region Ⅵ (the Huangdun Inlet) and Region Ⅶ (the Tiegang Inlet)the water exchange speed is slow between these regions and the outside water,but is still significantly faster than other regions. The fastest is in Region Ⅵ, in which the original water accounts for 1.5% on the 15th day, and 0.3% on the 60th day. And the slowest is in Huangdun Inlet Ⅳ, in which the original water accounts for 22.7% on the 15th day, and 4.4% on the 60th day. Furthermore, the matrix suggests that water exchanges between the Xihu Inlet and the Huangdun Inlet and three inner inlets are very weak.
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