2004 Vol. 23, No. 1
Display Method:
2004, (1): 1-10.
Abstract:
On the basis of the hydrographic data obtained from June 17 to 25, 1999 on board R/V Eardo, Korea (hereafter "the sec-ond cruise"), the circulation in the southern Huanghai Sea and East China Sea is computed by using the modified inverse method. The comparison between the two computed results in the first cruise, which was carried out from June 4 to 19, 1999 on board R/V Xiangyanghong 14, China, and in the second cruise is made. The following results have been obtained. (1) Part of the Kuroshio flows northward through the eastern part of Section E, and its volume transport(VT) is about 6.2×106 m3/s,and its maximum velocity is about 93 cm/s. This shows that most of the Kuroshio flows northward through the region east of Section E.The VT of the offshore branch of Taiwan Warm Current west of the Kuroshio through Section E is about 0.4×106 m3/s. (2) There is the following variability between these two cruises, whose time difference is about two weeks:①The position of the Kuroshio in the second cruise is slightly more east than that in the first cruise;②The high-density water(HDW)with a cold water occurs in the region south of Cheju Island between 125°30' and 127°E at Sections D and C. The circulation in the region of HDW is cyclonic. Comparing the position of HDW during the second cruise with that during the first cruise,it is found that its position in the second cruise moves slightly northward.(3) The cold and uniform mixing layer occurs in the layer from the 30 m level to the bottom of the middle part of Section A and in the layer from the 20 m level to the bottom of the middle part of Section B,respectively.They are both the southern part of the Huanghai Sea Cold Water Mass (HSCWM). (4) There are higher temperature and lower density with a weaker anticyclonic circulation in the southwestern part of the computed region. Its center is located at the western most point of Section E.
On the basis of the hydrographic data obtained from June 17 to 25, 1999 on board R/V Eardo, Korea (hereafter "the sec-ond cruise"), the circulation in the southern Huanghai Sea and East China Sea is computed by using the modified inverse method. The comparison between the two computed results in the first cruise, which was carried out from June 4 to 19, 1999 on board R/V Xiangyanghong 14, China, and in the second cruise is made. The following results have been obtained. (1) Part of the Kuroshio flows northward through the eastern part of Section E, and its volume transport(VT) is about 6.2×106 m3/s,and its maximum velocity is about 93 cm/s. This shows that most of the Kuroshio flows northward through the region east of Section E.The VT of the offshore branch of Taiwan Warm Current west of the Kuroshio through Section E is about 0.4×106 m3/s. (2) There is the following variability between these two cruises, whose time difference is about two weeks:①The position of the Kuroshio in the second cruise is slightly more east than that in the first cruise;②The high-density water(HDW)with a cold water occurs in the region south of Cheju Island between 125°30' and 127°E at Sections D and C. The circulation in the region of HDW is cyclonic. Comparing the position of HDW during the second cruise with that during the first cruise,it is found that its position in the second cruise moves slightly northward.(3) The cold and uniform mixing layer occurs in the layer from the 30 m level to the bottom of the middle part of Section A and in the layer from the 20 m level to the bottom of the middle part of Section B,respectively.They are both the southern part of the Huanghai Sea Cold Water Mass (HSCWM). (4) There are higher temperature and lower density with a weaker anticyclonic circulation in the southwestern part of the computed region. Its center is located at the western most point of Section E.
2004, (1): 11-22.
Abstract:
Using the hydrographic data obtained from two sectional observations crossing the Luzon strait in the summer of 1994 and in the winter of 1998, the volume transport through this strait is calculated. It is found that in winter the volume transport (4.45×106 m3/s) is far larger than that in the summer (2.0×106 m3/s), respectively being about equal to 15.0% and 6.9% of the Kuroshio.And the paths of water in and out of the section of the strait vary distinctly with the season. In summer, the water flows in and out of the South China Sea (SCS) three times:that is, the inlet passages almost appear on the southern sides of the three deep troughs,the outlet passages are all located on the northern sides of the troughs,and the in-out volume transports through the channel are not lower than 4.0×106 m3/s. The highest velocity (>80 cm/s) and the largest entering water capacity (6.6×106 m3/s) all occur in the Balintang Channel. Except for the north outlet passage in the section, all the higher velocities over 10 cm/s are mainly distributed on the layer above 500 m. In winter,the water flows in and out of the strait two times:the southern sides of the second and third deep troughs are the main passages of the Kuroshio water running into the SCS,while the whole section of the first deep trough and the bottom section of thesecond deep trough are the outlet passages. The higher velocities over 10 cm/s are almost distributed on the layer above 300m. Numerical calculation shows that the northern side of the third trough may be the outlet passage.
Using the hydrographic data obtained from two sectional observations crossing the Luzon strait in the summer of 1994 and in the winter of 1998, the volume transport through this strait is calculated. It is found that in winter the volume transport (4.45×106 m3/s) is far larger than that in the summer (2.0×106 m3/s), respectively being about equal to 15.0% and 6.9% of the Kuroshio.And the paths of water in and out of the section of the strait vary distinctly with the season. In summer, the water flows in and out of the South China Sea (SCS) three times:that is, the inlet passages almost appear on the southern sides of the three deep troughs,the outlet passages are all located on the northern sides of the troughs,and the in-out volume transports through the channel are not lower than 4.0×106 m3/s. The highest velocity (>80 cm/s) and the largest entering water capacity (6.6×106 m3/s) all occur in the Balintang Channel. Except for the north outlet passage in the section, all the higher velocities over 10 cm/s are mainly distributed on the layer above 500 m. In winter,the water flows in and out of the strait two times:the southern sides of the second and third deep troughs are the main passages of the Kuroshio water running into the SCS,while the whole section of the first deep trough and the bottom section of thesecond deep trough are the outlet passages. The higher velocities over 10 cm/s are almost distributed on the layer above 300m. Numerical calculation shows that the northern side of the third trough may be the outlet passage.
2004, (1): 23-30.
Abstract:
To investigate the interaction between the tropical Pacific and China seas a variable-grid global ocean circulation model with fine grid[(1/6)°] covering the area from 20°S to 50°N and from 99° to 150°E is developed. Numerical computation of the annually cyclic circulation fields is performed. The results of the annual mcan zonal currents and deep to abyssal western boundary currents in the equatorial Pacific Ocean are reported. The North Equatorial Current, the North Equatorial Countereurrent, the South Equatorial Current and the Equatorial Undercurrent are fairly well simulated. The model well reproduces the northward flowing abyssal western boundary current. From the model results a lower deep western boundary current east of the Bismarck-Solomon-New Hebrides Island chain at depths around 2 000 m has been found. The model results also show that the currents in the equatorial Pacific Ocean have multi-layer structures both in zonal currents and western boundary currents, indicating that the global ocean overturning thermohaline circulation appears of multi-layer pattern.
To investigate the interaction between the tropical Pacific and China seas a variable-grid global ocean circulation model with fine grid[(1/6)°] covering the area from 20°S to 50°N and from 99° to 150°E is developed. Numerical computation of the annually cyclic circulation fields is performed. The results of the annual mcan zonal currents and deep to abyssal western boundary currents in the equatorial Pacific Ocean are reported. The North Equatorial Current, the North Equatorial Countereurrent, the South Equatorial Current and the Equatorial Undercurrent are fairly well simulated. The model well reproduces the northward flowing abyssal western boundary current. From the model results a lower deep western boundary current east of the Bismarck-Solomon-New Hebrides Island chain at depths around 2 000 m has been found. The model results also show that the currents in the equatorial Pacific Ocean have multi-layer structures both in zonal currents and western boundary currents, indicating that the global ocean overturning thermohaline circulation appears of multi-layer pattern.
2004, (1): 31-40.
Abstract:
By using the upper layer data (downloaded trom the web of the Scripps Institution of Oceanography),the interannual variability of the heat storage of upper layer(from surface to 400 m depth) and the mixed layer depth in the tropical Pacific Ocean are investigated. The abnormal signal of the warm event comes from the central and west Pacific Ocean, whereas it is regarded that the abnormal signal of the warm event comes from the east Pacific Ocean in the popular viewpoint. From the viewpoint on the evolution of the interannual variability of the mixed layer depth and the heat storage of the whole upper layer, the difference between the two types of El Nino is so smallthat it can be neglected. During these two El Nino/La Nina events(1972/1973 and 1997/1998), other than the case of the heat storage or for the mixed layer depth, the abnormal signal propagates from the central and west Pacific Ocean to the east usually by the path along the equator whereas the abnormal signal propagates from the east to the west by the path northern to the equator. For the interannual variability, the evolution of the mixed layer depth corresponds to that of the heat storage in the upper layer very well. This is quite different from the evolution of seasonality.
By using the upper layer data (downloaded trom the web of the Scripps Institution of Oceanography),the interannual variability of the heat storage of upper layer(from surface to 400 m depth) and the mixed layer depth in the tropical Pacific Ocean are investigated. The abnormal signal of the warm event comes from the central and west Pacific Ocean, whereas it is regarded that the abnormal signal of the warm event comes from the east Pacific Ocean in the popular viewpoint. From the viewpoint on the evolution of the interannual variability of the mixed layer depth and the heat storage of the whole upper layer, the difference between the two types of El Nino is so smallthat it can be neglected. During these two El Nino/La Nina events(1972/1973 and 1997/1998), other than the case of the heat storage or for the mixed layer depth, the abnormal signal propagates from the central and west Pacific Ocean to the east usually by the path along the equator whereas the abnormal signal propagates from the east to the west by the path northern to the equator. For the interannual variability, the evolution of the mixed layer depth corresponds to that of the heat storage in the upper layer very well. This is quite different from the evolution of seasonality.
2004, (1): 41-50.
Abstract:
Three numerical oceanic circulation models:POM(Princeton ocean model), MICOM(Miami isopycnal coordinates ocean model) and GFDL model, which adopt sigma coordinate, isopycnal coordinate and depth coordinate respectively,are used in the South China Sea(SCS) circulation modeling. Model domain has the same topography, grid resolution,initial conditions and surface boundary conditions. The maximum ocean depth is set as 1000 m. Grid resolution is 0.5°×0.5°.Initial conditions are supplied by climatological temperature and salinity data in January. Climatological wind stress, surface temperature and salinity are used as surface forcing. Lateral boundaries take enclosed boundary conditions artificially. Focusing on the common point of different ocean circulation models, the circulation pattern in winter and summer, sea surface height in the northern SCS, seasonal cycle of the mixed layer thickness in the southem SCS,barotropic stream function in winter are selected to carry out intercomparison. In winter, a strong cyclonic gyre occupies the whole SCS. In summer, a strong anticyclonic gyre occupies the southern SCS and a weak cyclonic gyre occupies the northern SCS. The thickness of the mixed layer shows bimodal features in the southern SCS. Sea surface height anomaly(SSHA) in the northern SCS has an eastward propagating feature, in agreement with the remote sensing observation. Barotropic stream functions indicate that the circulation of the upper ocean is mainly forced by inputting of wind stress curl under closed boundary conditions. In addition, three models also show distinct differences. The basinscale circulation fiom MICOM is distinct. Output of POM has more mesoscale eddies than others. GFDL model seems good at simulating westward intensification.
Three numerical oceanic circulation models:POM(Princeton ocean model), MICOM(Miami isopycnal coordinates ocean model) and GFDL model, which adopt sigma coordinate, isopycnal coordinate and depth coordinate respectively,are used in the South China Sea(SCS) circulation modeling. Model domain has the same topography, grid resolution,initial conditions and surface boundary conditions. The maximum ocean depth is set as 1000 m. Grid resolution is 0.5°×0.5°.Initial conditions are supplied by climatological temperature and salinity data in January. Climatological wind stress, surface temperature and salinity are used as surface forcing. Lateral boundaries take enclosed boundary conditions artificially. Focusing on the common point of different ocean circulation models, the circulation pattern in winter and summer, sea surface height in the northern SCS, seasonal cycle of the mixed layer thickness in the southem SCS,barotropic stream function in winter are selected to carry out intercomparison. In winter, a strong cyclonic gyre occupies the whole SCS. In summer, a strong anticyclonic gyre occupies the southern SCS and a weak cyclonic gyre occupies the northern SCS. The thickness of the mixed layer shows bimodal features in the southern SCS. Sea surface height anomaly(SSHA) in the northern SCS has an eastward propagating feature, in agreement with the remote sensing observation. Barotropic stream functions indicate that the circulation of the upper ocean is mainly forced by inputting of wind stress curl under closed boundary conditions. In addition, three models also show distinct differences. The basinscale circulation fiom MICOM is distinct. Output of POM has more mesoscale eddies than others. GFDL model seems good at simulating westward intensification.
2004, (1): 51-60.
Abstract:
Based on the TOGA-TAO buoy chain observed data in the equatorial Pacific and the assimilation analysis results from SODA(simple ocean data assimilation analysis), the role of the meridional cells in the subsurface of the tropical Pacific was discussed. It was found that, the seasonal varying direction of EUC(the quatorial Undercurrent)in the Peacific is westwards beginning from the eastern equatorial Pacific in the boreal spring. The meridional cell south of the equator plays important role on this seasonal change of EUC.On the other hand, although the varying direction is westwards,the seasonal variation of temperature in the same region gets its minimum values in the boreal anttmm beginning from the eastern equatorial Pacific.The meridional cell north of the equator is most responsible for the seasonal temperature variation in the eastern equatorial Pacific while the meridional cell south of the equator mainly controls the seasonal temperature change in the central Pacific. It is probably true that the asymmetry by the equator is an important factor influencing the seasonal cycle of EUC and temperature in the tropical Pacific.
Based on the TOGA-TAO buoy chain observed data in the equatorial Pacific and the assimilation analysis results from SODA(simple ocean data assimilation analysis), the role of the meridional cells in the subsurface of the tropical Pacific was discussed. It was found that, the seasonal varying direction of EUC(the quatorial Undercurrent)in the Peacific is westwards beginning from the eastern equatorial Pacific in the boreal spring. The meridional cell south of the equator plays important role on this seasonal change of EUC.On the other hand, although the varying direction is westwards,the seasonal variation of temperature in the same region gets its minimum values in the boreal anttmm beginning from the eastern equatorial Pacific.The meridional cell north of the equator is most responsible for the seasonal temperature variation in the eastern equatorial Pacific while the meridional cell south of the equator mainly controls the seasonal temperature change in the central Pacific. It is probably true that the asymmetry by the equator is an important factor influencing the seasonal cycle of EUC and temperature in the tropical Pacific.
2004, (1): 61-72.
Abstract:
The interdecadal variation of Pacific thermocline represented by depth anomalies of 25 σθ isopycnal surface calculated from SODA data set is analyzed. The climatological depth of 25 σθ isopycnal surface is quite close to the depth of 20℃ isotherm in the tropical Pacific. The EOF1 mode of the 25 σθ isopycnal surface accounts for 26.4% of the total variance and its associated pattern is of east-west direction. The centers of positive and negative extremes are located near 10°S over the southern Pacific and the correlation coefficient with zero-lag between the corresponding EOF1 time coefficient and PDO index is -0.67. This shows that there is very close relation between the southern tropical Pacific and PDO.The wavelet analysis ofdetrended EOF1 time coefficient reveals that there are two dominant time scales of about 3~7 and 30 a respectively. An apparent abruptness of mean value occurred in the late 1970s. EOF2 mode accounts for 12.4% of the total variance and its pattern is an ENSO-related one. The correlation coefficient between the EOF2 time coefficient and NINO3 index is -0.68. The wavelet analysis of EOF2 time coefficient reveals that there are two leading time scales of about 2~7 and 10~15 a respectively. On an interdecadal scale, the zonal change is consistent along the equator and is seesaw along 10°S; there is consistent polarity in the tropics along 165°E, but reverse polarity between around equator and other tropical region along 120°W. In all the four profiles mentioned above, the regime shift occurred in the late 1970s. The evolving characteristics of anomalies can be explained mostly by the anomalies of ocean currents during a complete cycle on an interdecadal scale.
The interdecadal variation of Pacific thermocline represented by depth anomalies of 25 σθ isopycnal surface calculated from SODA data set is analyzed. The climatological depth of 25 σθ isopycnal surface is quite close to the depth of 20℃ isotherm in the tropical Pacific. The EOF1 mode of the 25 σθ isopycnal surface accounts for 26.4% of the total variance and its associated pattern is of east-west direction. The centers of positive and negative extremes are located near 10°S over the southern Pacific and the correlation coefficient with zero-lag between the corresponding EOF1 time coefficient and PDO index is -0.67. This shows that there is very close relation between the southern tropical Pacific and PDO.The wavelet analysis ofdetrended EOF1 time coefficient reveals that there are two dominant time scales of about 3~7 and 30 a respectively. An apparent abruptness of mean value occurred in the late 1970s. EOF2 mode accounts for 12.4% of the total variance and its pattern is an ENSO-related one. The correlation coefficient between the EOF2 time coefficient and NINO3 index is -0.68. The wavelet analysis of EOF2 time coefficient reveals that there are two leading time scales of about 2~7 and 10~15 a respectively. On an interdecadal scale, the zonal change is consistent along the equator and is seesaw along 10°S; there is consistent polarity in the tropics along 165°E, but reverse polarity between around equator and other tropical region along 120°W. In all the four profiles mentioned above, the regime shift occurred in the late 1970s. The evolving characteristics of anomalies can be explained mostly by the anomalies of ocean currents during a complete cycle on an interdecadal scale.
2004, (1): 73-82.
Abstract:
The relationship between sea surface temperature anomaly (SSTA) in the domain from the northwest of thc Pacific to Chinaseas (NWP-CS) andclimate (precipitation and surface temperature) anomaly in winters over east of Chinese Mainland (ECM) are investigated with composite analysis. The results suggest that (1) SSTA in NWP-CS usually appears as "seesaw" pattern, I.e., sign of SSTA in the northwest of thc Philippines is positive (negative) while in the southeast it is negative (positive), defmed as SSTA "seesaw" positive (negative) pattern. When SSTA "seesaw" positive(negative) pattern appears, the surface temperature in ECM is higher (lower) than the normal winters but thc precipitation anomaly is not distinct; (2) there are two anomalous anticyclones (cyclones) locating in the northwest Pacific and east of the Philippines at 850 hPa level and an anomalous anti-Hadley (Hadley) circulation, which descends (ascends)south of 18°N, ascends (descends) north of 18°N; (3) heat flux anomaly from ocean into atmosphere is weaker (stronger)in the northwest of the Philippines but stronger (weaker) in the southeast of the Philippines than the normal winters, because the weaker (stronger) northerly prevails in thc northwest of the Philippines and stronger (weaker) northeaster in the southeast of the Philippines induced by anomalous anticyclones (cyclones).
The relationship between sea surface temperature anomaly (SSTA) in the domain from the northwest of thc Pacific to Chinaseas (NWP-CS) andclimate (precipitation and surface temperature) anomaly in winters over east of Chinese Mainland (ECM) are investigated with composite analysis. The results suggest that (1) SSTA in NWP-CS usually appears as "seesaw" pattern, I.e., sign of SSTA in the northwest of thc Philippines is positive (negative) while in the southeast it is negative (positive), defmed as SSTA "seesaw" positive (negative) pattern. When SSTA "seesaw" positive(negative) pattern appears, the surface temperature in ECM is higher (lower) than the normal winters but thc precipitation anomaly is not distinct; (2) there are two anomalous anticyclones (cyclones) locating in the northwest Pacific and east of the Philippines at 850 hPa level and an anomalous anti-Hadley (Hadley) circulation, which descends (ascends)south of 18°N, ascends (descends) north of 18°N; (3) heat flux anomaly from ocean into atmosphere is weaker (stronger)in the northwest of the Philippines but stronger (weaker) in the southeast of the Philippines than the normal winters, because the weaker (stronger) northerly prevails in thc northwest of the Philippines and stronger (weaker) northeaster in the southeast of the Philippines induced by anomalous anticyclones (cyclones).
2004, (1): 83-90.
Abstract:
Based on the output data from 1997 to 2000 obtained by the MITgcm's (general circulation model) adjoint assimilation method, volume, heat and salt transports through the Luzon Strait are calculated. The results indicate that there are obvious different characteristics between 1997 and 1998~2000 on the transports through the Luzon Strait. During 1997, theLuzon Strait had a mean net westward transport of 3.93×106 m3/s with a maximum transport of 7.34×106 m3/s in October. During 1998~2000, the Luzon Strait possessed an annual mean eastward transport of 0.93×106, 1.80×106 and 1.00×106 m3/s respectively with a maximum eastward transport of 4.10×106/3.31×106 m3/s in July 1998/1999 and 2.06×106 m3/s in April 2000, respectively. Moreover, the transports in 1997 indicated a difference from the other years, i.e.,that the ranges of westward inflows expanded more obviously to north of the Luzon Strait and downwards exceedingthose of the other years. The westward inflows expanded horizontally to the north part of the Luzon Strait until 21°N.
Based on the output data from 1997 to 2000 obtained by the MITgcm's (general circulation model) adjoint assimilation method, volume, heat and salt transports through the Luzon Strait are calculated. The results indicate that there are obvious different characteristics between 1997 and 1998~2000 on the transports through the Luzon Strait. During 1997, theLuzon Strait had a mean net westward transport of 3.93×106 m3/s with a maximum transport of 7.34×106 m3/s in October. During 1998~2000, the Luzon Strait possessed an annual mean eastward transport of 0.93×106, 1.80×106 and 1.00×106 m3/s respectively with a maximum eastward transport of 4.10×106/3.31×106 m3/s in July 1998/1999 and 2.06×106 m3/s in April 2000, respectively. Moreover, the transports in 1997 indicated a difference from the other years, i.e.,that the ranges of westward inflows expanded more obviously to north of the Luzon Strait and downwards exceedingthose of the other years. The westward inflows expanded horizontally to the north part of the Luzon Strait until 21°N.
2004, (1): 91-96.
Abstract:
Based on TOPEX/Poseidon (T/P) and ERS-1 and 2 satellite altimeter data between October 1992 and December 2000,high frequency oscillations with periods less than 150 d are analyzed and their spatial distributions are described. Theratio, instead of the energy itself, of the energy corresponding to certain frequency band from power spectrun relative tothe total energy in the 20~143 d range is analyzed. The results show that the period of the most energetic oscillations inthis band increases with latitude from about 1 month near the tropics to about 4 months near 30°, in agreement with thelatitudinal dependency of the phase speed of westward propagating long Rossby waves,which dominate the variabilityin those latitudes. As a result,the global spatial distributions of the period of the dominant oscillations are largely zonal,with relatively small differences between different ocean basins. It suggests that the oscillations with periods around 60 d are mainly associated with planetary Rossby waves except the often regarded as tidal aliasing.
Based on TOPEX/Poseidon (T/P) and ERS-1 and 2 satellite altimeter data between October 1992 and December 2000,high frequency oscillations with periods less than 150 d are analyzed and their spatial distributions are described. Theratio, instead of the energy itself, of the energy corresponding to certain frequency band from power spectrun relative tothe total energy in the 20~143 d range is analyzed. The results show that the period of the most energetic oscillations inthis band increases with latitude from about 1 month near the tropics to about 4 months near 30°, in agreement with thelatitudinal dependency of the phase speed of westward propagating long Rossby waves,which dominate the variabilityin those latitudes. As a result,the global spatial distributions of the period of the dominant oscillations are largely zonal,with relatively small differences between different ocean basins. It suggests that the oscillations with periods around 60 d are mainly associated with planetary Rossby waves except the often regarded as tidal aliasing.
2004, (1): 97-108.
Abstract:
To meet the increasing demand of national spatial database infrastructureconstruction and application, a concept modelof China's coastal zone scientific data platform is established based on the information feature analysis of a compounddataset, consisting of remote sensing data and conventional data. Based on this concept model, the detailed logicaldatabase structure and the storage strategy of remote sensing data and their metadata using ArcSDE are designed. Thecomplicated technology of multisources data combination in this research is crucial to the future coastal zone andoffshore database construction and practical nmning, which will provide intelligent information analysis andtechnological service for coastal zone and offshore investigation, research, development and management.
To meet the increasing demand of national spatial database infrastructureconstruction and application, a concept modelof China's coastal zone scientific data platform is established based on the information feature analysis of a compounddataset, consisting of remote sensing data and conventional data. Based on this concept model, the detailed logicaldatabase structure and the storage strategy of remote sensing data and their metadata using ArcSDE are designed. Thecomplicated technology of multisources data combination in this research is crucial to the future coastal zone andoffshore database construction and practical nmning, which will provide intelligent information analysis andtechnological service for coastal zone and offshore investigation, research, development and management.
2004, (1): 109-118.
Abstract:
China's coastal zone is a region with a highly developed economy that contrasts clearly with the slow paced regular investigation on its natural environment,which cannot keep pace with the requirement of economic development and modem management. Laying a theoretical foundation for the modem management of China's costal zone is aimed at.This research focuses on the following processing and analyzing technologies for coastal zone high-resolution remote sensing data:organization and management of large amounts of high-resolution remote sensing data, quick and precise spatial positioning system,algorithms for image fusion in feature level and coastal zone feature extraction. They will form a technical foundation of the system. And, if combined with other research results such as coastal zone remote sensing classification system and its mapping subsystem, an advanced technical frame for remote sensing investigation of coastal zone resource will be constructed.
China's coastal zone is a region with a highly developed economy that contrasts clearly with the slow paced regular investigation on its natural environment,which cannot keep pace with the requirement of economic development and modem management. Laying a theoretical foundation for the modem management of China's costal zone is aimed at.This research focuses on the following processing and analyzing technologies for coastal zone high-resolution remote sensing data:organization and management of large amounts of high-resolution remote sensing data, quick and precise spatial positioning system,algorithms for image fusion in feature level and coastal zone feature extraction. They will form a technical foundation of the system. And, if combined with other research results such as coastal zone remote sensing classification system and its mapping subsystem, an advanced technical frame for remote sensing investigation of coastal zone resource will be constructed.
2004, (1): 119-128.
Abstract:
It is a valid route for quantitatively remote sensing on water pollution to build a model according to the physical mechanisms of scattering and absorbing of suspended substance, pollutant, and molecules of water. Remote sensing model for water pollution based on single scattering is simple and easy to be used, but the precision is affected by turbidity of water. The characteristics of the energy composition of multiple scattering, are analyzed and it is proposed that, based on the model of single scattering, ifthe flux of the second scattering is considered additionally, the precision of the modelwill be remarkably improved and the calculation is still very simple. The factor of the second scattering is deduced to build a double scattering model, and the practical arithmetic for the calculation of the model is put forward. The result of applying this model in the water area around the Zhujiang(Pearl) River outfall shows that the precision is obviously improved. The result also shows that the seriously polluted water area is distributed in the northeast of Lingding Sea, the Victoria Bay of Hong Kong, and the Shengzhen Bay.
It is a valid route for quantitatively remote sensing on water pollution to build a model according to the physical mechanisms of scattering and absorbing of suspended substance, pollutant, and molecules of water. Remote sensing model for water pollution based on single scattering is simple and easy to be used, but the precision is affected by turbidity of water. The characteristics of the energy composition of multiple scattering, are analyzed and it is proposed that, based on the model of single scattering, ifthe flux of the second scattering is considered additionally, the precision of the modelwill be remarkably improved and the calculation is still very simple. The factor of the second scattering is deduced to build a double scattering model, and the practical arithmetic for the calculation of the model is put forward. The result of applying this model in the water area around the Zhujiang(Pearl) River outfall shows that the precision is obviously improved. The result also shows that the seriously polluted water area is distributed in the northeast of Lingding Sea, the Victoria Bay of Hong Kong, and the Shengzhen Bay.
2004, (1): 129-134.
Abstract:
Organic carbon (OC) in definitely small area sediments(according to marine dimension)off the Huanghe River Estuary is investigated in order to evaluate the feature of regional difference of physical and chemical properties in marginal sea sediments. The distributions of OC in sediments with natural grain size and the relationship with the pH,Eh,Es and Fe3+/Fe2+ are discussed. In addition, OC decomposition rates in surfacial/subsurfacial sediments are estimated. OC concentrations range from 0.26% to 1.8%(wt)in the study area. Significant differences in OC content and in horizontal distribution as well as various trends in surfacial/subsurfacial sediments exhibit the feature of regional difference remarkably in marginal sea sediments. The complicated distribution of OC in surface sediments is due to the influence of bacterial activity and abundance, bioturbation of benthos and physical disturbance. The OC decomposition rate constant in surfacial/subsurfacial sediments ranges from 0.009 7 to 0.076 a-1 and the relatively high values may be mainly related to bacteria that are mainly responsible for OC mineralization;meio-and macrofauna affect OC degradation both directly, through feeding on it, and indirectly through bioturbation and at the same time coarse sediments are also disadvantageous to OC preservation. In almost all the middle and bottom sediments the contents of Ocdecrease with the increase of deposition depth, which indicates that mineralization of OC in the middle and bottom sediments has occurred via processes like SO42- reduction and Fe-oxide reduction.
Organic carbon (OC) in definitely small area sediments(according to marine dimension)off the Huanghe River Estuary is investigated in order to evaluate the feature of regional difference of physical and chemical properties in marginal sea sediments. The distributions of OC in sediments with natural grain size and the relationship with the pH,Eh,Es and Fe3+/Fe2+ are discussed. In addition, OC decomposition rates in surfacial/subsurfacial sediments are estimated. OC concentrations range from 0.26% to 1.8%(wt)in the study area. Significant differences in OC content and in horizontal distribution as well as various trends in surfacial/subsurfacial sediments exhibit the feature of regional difference remarkably in marginal sea sediments. The complicated distribution of OC in surface sediments is due to the influence of bacterial activity and abundance, bioturbation of benthos and physical disturbance. The OC decomposition rate constant in surfacial/subsurfacial sediments ranges from 0.009 7 to 0.076 a-1 and the relatively high values may be mainly related to bacteria that are mainly responsible for OC mineralization;meio-and macrofauna affect OC degradation both directly, through feeding on it, and indirectly through bioturbation and at the same time coarse sediments are also disadvantageous to OC preservation. In almost all the middle and bottom sediments the contents of Ocdecrease with the increase of deposition depth, which indicates that mineralization of OC in the middle and bottom sediments has occurred via processes like SO42- reduction and Fe-oxide reduction.
2004, (1): 135-148.
Abstract:
Dissolved and particulate 234Th, particulate organic carbon(PON), nitrogen, and chlorophyll-a concentrations in the upper 200 m of water columns from seven stations in the northwestern North Pacific Ocean were determined in the winter of 1997.The dissolved, particulate, and total 234Th activities (dissolved plus particulate)show a pronounced deficiency with respect to its parent 238U in the euphoric zone whereas the total 234Th shows a near-equilibrium at the depth greaterthan 100 m. The 234Th data are used to derive the mean residence time, export fluxes of 234Th, and fluxes of particulate organic carbon and nitrogen out of the euphotic zone. In the Subarctic Current area, the residence time of dissolved 234 Thwith respect to its removal onto particles is 40~50 d while the residence time of dissolved 234Th in the subtropical area is about 20 d due to the Kuroshio's influence.The particulate organic carbon (POC)and particulate organic nitroge(PON) fluxes in water range over 3.8~8.2 and 0.50~0.98 mmol/(m2·d),repectively,and are higher in the west region than in the east, and higher in the south than in the north. The co-influence of Kuroshio-Oyashio Currents withsupply of nutrient substances from the coastal area and the light condition are two factors determining the horizontaldistribution of POC fluxes in winter. The depth distribution of the chlorophyll-a as well as the consistence of the ratio ofPOC to PON with the Redfield ratio suggest that phytoplankton is the main contributor to the export of POC in this areain winter. The POC fluxes in the northwestern North Pacific Ocean in winter are comparable to some areas in the worldoceans in spring and summer seasons.
Dissolved and particulate 234Th, particulate organic carbon(PON), nitrogen, and chlorophyll-a concentrations in the upper 200 m of water columns from seven stations in the northwestern North Pacific Ocean were determined in the winter of 1997.The dissolved, particulate, and total 234Th activities (dissolved plus particulate)show a pronounced deficiency with respect to its parent 238U in the euphoric zone whereas the total 234Th shows a near-equilibrium at the depth greaterthan 100 m. The 234Th data are used to derive the mean residence time, export fluxes of 234Th, and fluxes of particulate organic carbon and nitrogen out of the euphotic zone. In the Subarctic Current area, the residence time of dissolved 234 Thwith respect to its removal onto particles is 40~50 d while the residence time of dissolved 234Th in the subtropical area is about 20 d due to the Kuroshio's influence.The particulate organic carbon (POC)and particulate organic nitroge(PON) fluxes in water range over 3.8~8.2 and 0.50~0.98 mmol/(m2·d),repectively,and are higher in the west region than in the east, and higher in the south than in the north. The co-influence of Kuroshio-Oyashio Currents withsupply of nutrient substances from the coastal area and the light condition are two factors determining the horizontaldistribution of POC fluxes in winter. The depth distribution of the chlorophyll-a as well as the consistence of the ratio ofPOC to PON with the Redfield ratio suggest that phytoplankton is the main contributor to the export of POC in this areain winter. The POC fluxes in the northwestern North Pacific Ocean in winter are comparable to some areas in the worldoceans in spring and summer seasons.
2004, (1): 149-158.
Abstract:
Influence of waterlogging time on the growth of Kandelia candel(L.) Druce seedlings grown for 70 d in the artificial-tidal tanks' simulated semidiumal tide under greenhouse is studied. Sand and soil act as the substrate and artificial sea-water with salinity of 15 is used in cultivation. Shorter waterlogging time (inundated for about 2~4 h) promotes thegrowth of K. candel seedlings, while longer time(inundated more than 8 h) or no waterlogging(0 h) inhibits theirgrowth. The number and length of aerating roots increase with the increase ofwaterlogging time. Under existing conditions, the optimal waterlogging time for the growth of K. candel seedlings is about 2~4 h in every tide cycle. Compared with other treatments, the 2 h sanded treatments obtain the highest biomass of seedlings, have the lowest massloss of hypocotyl and broaden the photosynthetic area by increasing the area per leaf after 70-d cultivation. And the soiltreatments have the similar tendeney. However, waterlogging for 8 h in every tide cycle is critieal for normal development of seedlings. K. candel seedlings are highly tolerant to waterlogging and a proper waterlogging is beneficial to thegrowth of K. candel seedlings.
Influence of waterlogging time on the growth of Kandelia candel(L.) Druce seedlings grown for 70 d in the artificial-tidal tanks' simulated semidiumal tide under greenhouse is studied. Sand and soil act as the substrate and artificial sea-water with salinity of 15 is used in cultivation. Shorter waterlogging time (inundated for about 2~4 h) promotes thegrowth of K. candel seedlings, while longer time(inundated more than 8 h) or no waterlogging(0 h) inhibits theirgrowth. The number and length of aerating roots increase with the increase ofwaterlogging time. Under existing conditions, the optimal waterlogging time for the growth of K. candel seedlings is about 2~4 h in every tide cycle. Compared with other treatments, the 2 h sanded treatments obtain the highest biomass of seedlings, have the lowest massloss of hypocotyl and broaden the photosynthetic area by increasing the area per leaf after 70-d cultivation. And the soiltreatments have the similar tendeney. However, waterlogging for 8 h in every tide cycle is critieal for normal development of seedlings. K. candel seedlings are highly tolerant to waterlogging and a proper waterlogging is beneficial to thegrowth of K. candel seedlings.
2004, (1): 159-168.
Abstract:
The topography data of the Zengmu Shoal and its adjacent area are acquired by the SeaBat-8111 multibeam system.The full survey covering over the Zengmu Shoal area gives us new knowledge about the area. It is a flat underwater plat-form consisting of coral reefs, its fathom line is like a trap in near SN direction and its shape is like an isosceles triangle with the acute angle pointing to the north. The east and west sides of the shoal are steep while its south side is more gentle. As viewed from geological evolution, the Zengmu Shoal is a typical biologic coral landform caused by tectonic uplift.
The topography data of the Zengmu Shoal and its adjacent area are acquired by the SeaBat-8111 multibeam system.The full survey covering over the Zengmu Shoal area gives us new knowledge about the area. It is a flat underwater plat-form consisting of coral reefs, its fathom line is like a trap in near SN direction and its shape is like an isosceles triangle with the acute angle pointing to the north. The east and west sides of the shoal are steep while its south side is more gentle. As viewed from geological evolution, the Zengmu Shoal is a typical biologic coral landform caused by tectonic uplift.
2004, (1): 169-178.
Abstract:
A reformed numerical model based on the "one-line theory" for beach deformation is presented. In this model, the change of beach slope during coastline procession is eonsidered. A wave numerical model combined with wave refraction, diffraction and reflection is used to simulate wave climate to increase numerical accuracy. The results show that the numerical model has a good precision based on the adequate field data. The results can be applied to practical engineering.
A reformed numerical model based on the "one-line theory" for beach deformation is presented. In this model, the change of beach slope during coastline procession is eonsidered. A wave numerical model combined with wave refraction, diffraction and reflection is used to simulate wave climate to increase numerical accuracy. The results show that the numerical model has a good precision based on the adequate field data. The results can be applied to practical engineering.
2004, (1): 179-186.
Abstract:
Dissolved oxygen (DO) concentrations were surveyed in the Daliao River Estuary in autumn to investigate the temporaland spatial trends of DO distributions. The results indicate that DO is weakly stratified in the Yingkou section of the Daliao River Estuary, and remains constant vertically in the areas near and out of the entrance. Horizontally, both in-stantaneous and continuous observations show that the Yingkou section of the Daliao River Estuary is affected by hypoxic conditions; while no conditions of low DO have been observed in the areas near and out of the entrance.DO-salinity correlations exhibit different controlling factors of DO distributions in different sections of the Daliao River Estuary. At the upstream part of the Yingkou section of the Daliao River (A1-A4), oxygen demanding materials and the associated biochemical processes are the main factor controlling the DO distribution, but in the lower part of the Yingkou section and the area near and out of the entrance (A5-A15), tidal advections are more influential for DO distributions.
Dissolved oxygen (DO) concentrations were surveyed in the Daliao River Estuary in autumn to investigate the temporaland spatial trends of DO distributions. The results indicate that DO is weakly stratified in the Yingkou section of the Daliao River Estuary, and remains constant vertically in the areas near and out of the entrance. Horizontally, both in-stantaneous and continuous observations show that the Yingkou section of the Daliao River Estuary is affected by hypoxic conditions; while no conditions of low DO have been observed in the areas near and out of the entrance.DO-salinity correlations exhibit different controlling factors of DO distributions in different sections of the Daliao River Estuary. At the upstream part of the Yingkou section of the Daliao River (A1-A4), oxygen demanding materials and the associated biochemical processes are the main factor controlling the DO distribution, but in the lower part of the Yingkou section and the area near and out of the entrance (A5-A15), tidal advections are more influential for DO distributions.
