2018 Vol. 40, No. 3
Display Method:
2018, 40(3): .
Abstract:
2018, 40(3): 1-15.
doi: 10.3969/j.issn.0253-4193.2018.03.001
Abstract:
Using the climatology data of temperature and salinity from the World Ocean Atlas 2013 (WOA2013) and the ocean current data of the Simple Ocean Data Assimilation version 3.3.1 (SODA v3.3.1), the vertical distribution and water mass sources of the Indonesian Throughflow (ITF) in its east pathway are analyzed, especially the sub-surface, intermediate and deep waters in the Molukka Sea and Halmahera Sea. The results show that the warmer and saltier subsurface waters around 24.5σθ (about 150 m) in the Molukka Sea come from the North Pacific (NP), with characteristics close to those of the NP Tropic Water (NPTW), while the subsurface water in the Halmahera Sea is closely related to the South Pacific Tropical Water (SPTW). For the intermediate water around 26.8σθ (about 480 m), which is characterized by low temperature and low salinity, the South Pacific (SP) water intrudes into the Molukka Sea, and further enters the Halmahera Sea from the southwest straits. In the transition layer between the subsurface and intermediate waters, the waters in the Molukka Sea and Halmahera Sea are mixed waters from the NP and the SP. There is water exchange between the two seas. In the deep layer around 27.2σθ (about 850 m), the water in the Molukka Sea is inclined to being from the northern Banda Sea and the Selan Sea. The deep water in the Halmahera Sea is isolated without direct exchange with the Pacific water due to topographic barrier.
Using the climatology data of temperature and salinity from the World Ocean Atlas 2013 (WOA2013) and the ocean current data of the Simple Ocean Data Assimilation version 3.3.1 (SODA v3.3.1), the vertical distribution and water mass sources of the Indonesian Throughflow (ITF) in its east pathway are analyzed, especially the sub-surface, intermediate and deep waters in the Molukka Sea and Halmahera Sea. The results show that the warmer and saltier subsurface waters around 24.5σθ (about 150 m) in the Molukka Sea come from the North Pacific (NP), with characteristics close to those of the NP Tropic Water (NPTW), while the subsurface water in the Halmahera Sea is closely related to the South Pacific Tropical Water (SPTW). For the intermediate water around 26.8σθ (about 480 m), which is characterized by low temperature and low salinity, the South Pacific (SP) water intrudes into the Molukka Sea, and further enters the Halmahera Sea from the southwest straits. In the transition layer between the subsurface and intermediate waters, the waters in the Molukka Sea and Halmahera Sea are mixed waters from the NP and the SP. There is water exchange between the two seas. In the deep layer around 27.2σθ (about 850 m), the water in the Molukka Sea is inclined to being from the northern Banda Sea and the Selan Sea. The deep water in the Halmahera Sea is isolated without direct exchange with the Pacific water due to topographic barrier.
The dynamic characteristics of turbulence in the Modaomen Estuary river plume based on the ADCP data
2018, 40(3): 16-24.
doi: 10.3969/j.issn.0253-4193.2018.03.002
Abstract:
This thesis aimed to analyze the dynamic characteristics of turbulence with the field observation data getting by a 1 200 kHz, broadband RDI ADCP rigidly mounted in the front of the sand bar and in the deep-water zone in the Modaomen Estuary in July 2015, with the "variance method". The results show that the flow velocity presenta typical three-layer circulation structure, and high-speed velocity area appeared in the Modaomen Estuary river plume. The Reynolds stress estimated in the deep-water zone was between 10-3-10-5 m2/s2, and smaller than that in the front of sand bar. The turbulence kinetic energy density parameter was larger in the river plume than in the bottom, and the size of it in both place was between 0.01-0.6 m2/s2. In the front of the sand bar, the turbulence kinetic energy production rate was in the order of 10-3 W/kg in the river plume, 2-3 orders of magnitude lager than that in the bottom and stronger than that in the deep-water zone. The vertical eddy viscosity coefficient was between 0-0.15 m2/s. In general, the river plume presents a state of stably stratified, with strongly mixed and high turbulence kinetic energy production rate, which provides a dynamical condition for the long-distance transport of high turbidity suspended sediment.
This thesis aimed to analyze the dynamic characteristics of turbulence with the field observation data getting by a 1 200 kHz, broadband RDI ADCP rigidly mounted in the front of the sand bar and in the deep-water zone in the Modaomen Estuary in July 2015, with the "variance method". The results show that the flow velocity presenta typical three-layer circulation structure, and high-speed velocity area appeared in the Modaomen Estuary river plume. The Reynolds stress estimated in the deep-water zone was between 10-3-10-5 m2/s2, and smaller than that in the front of sand bar. The turbulence kinetic energy density parameter was larger in the river plume than in the bottom, and the size of it in both place was between 0.01-0.6 m2/s2. In the front of the sand bar, the turbulence kinetic energy production rate was in the order of 10-3 W/kg in the river plume, 2-3 orders of magnitude lager than that in the bottom and stronger than that in the deep-water zone. The vertical eddy viscosity coefficient was between 0-0.15 m2/s. In general, the river plume presents a state of stably stratified, with strongly mixed and high turbulence kinetic energy production rate, which provides a dynamical condition for the long-distance transport of high turbidity suspended sediment.
2018, 40(3): 25-35.
doi: 10.3969/j.issn.0253-4193.2018.03.003
Abstract:
The satellite altimeter data, sea surface temperature (SST) data and on-site sea level data are used to analyse the effects of the ENSO on the sea level in the offshore areas of China, and to investigate the regional characteristics of the effects of ENSO on the sea level in this paper. Results show that significant teleconnection exists between the SST of the tropical Pacific Ocean and the sea level in the China Sea, and the correlation coefficient decreases progressively from south to north. Thus the offshore areas of China can be divided into three regions:the Bohai and Yellow Sea, the East China Sea, and the South China Sea. The correlation in the South China Sea is the most significant, with the coefficient larger than 0.6 at most areas. The correlation coefficient in the East China Sea is smaller than that in the South China Sea but larger than that in the Bohai Sea and Yellow Sea, and in most areas the coefficient is larger than 0.4. The correlation in the Bohai and Yellow Sea is the weakest among the three areas, yet the correlation coefficient is larger than 0.3 and has passed the significant tests. The annual amplitudes of the sea levels at tide gauges along the coast of China are also studied. It reveals that the seasonal variations of the sea levels at tide gauges are significantly correlated with the ENSO and show distinctive regional characteristic. Thus according to the correlations, the coast of China can be separated into three regions, the area in the north of the Changjiang River Estuary, from Changjiang River Estuary to the Taiwan Strait and south of the Taiwan Strait. Furthermore, the results indicate that the annual amplitude of the sea levels is at low level in El Niño years, and the minimal annual amplitude during the whole period occurs in the El Niño year as well. And the response intensity of the annual amplitude of the sea levels to the ENSO is highly related to the intensity of the ENSO events. When the ENSO event is strong, the response region is relatively larger and the amplitude is bigger than normal situations. The sea levels show significant oscillation period scaled at about 4-7 years in the above three sea regions. For the fluctuation with the period of 7 years in the South China Sea, the oscillation amplitude is about 1.5 cm, which is the largest among all frequencies. In the East China Sea the amplitude is about 1.3 cm. The amplitude of the 6 years period in the Bohai Sea and Yellow Sea is the minimum, less than 1 cm.
The satellite altimeter data, sea surface temperature (SST) data and on-site sea level data are used to analyse the effects of the ENSO on the sea level in the offshore areas of China, and to investigate the regional characteristics of the effects of ENSO on the sea level in this paper. Results show that significant teleconnection exists between the SST of the tropical Pacific Ocean and the sea level in the China Sea, and the correlation coefficient decreases progressively from south to north. Thus the offshore areas of China can be divided into three regions:the Bohai and Yellow Sea, the East China Sea, and the South China Sea. The correlation in the South China Sea is the most significant, with the coefficient larger than 0.6 at most areas. The correlation coefficient in the East China Sea is smaller than that in the South China Sea but larger than that in the Bohai Sea and Yellow Sea, and in most areas the coefficient is larger than 0.4. The correlation in the Bohai and Yellow Sea is the weakest among the three areas, yet the correlation coefficient is larger than 0.3 and has passed the significant tests. The annual amplitudes of the sea levels at tide gauges along the coast of China are also studied. It reveals that the seasonal variations of the sea levels at tide gauges are significantly correlated with the ENSO and show distinctive regional characteristic. Thus according to the correlations, the coast of China can be separated into three regions, the area in the north of the Changjiang River Estuary, from Changjiang River Estuary to the Taiwan Strait and south of the Taiwan Strait. Furthermore, the results indicate that the annual amplitude of the sea levels is at low level in El Niño years, and the minimal annual amplitude during the whole period occurs in the El Niño year as well. And the response intensity of the annual amplitude of the sea levels to the ENSO is highly related to the intensity of the ENSO events. When the ENSO event is strong, the response region is relatively larger and the amplitude is bigger than normal situations. The sea levels show significant oscillation period scaled at about 4-7 years in the above three sea regions. For the fluctuation with the period of 7 years in the South China Sea, the oscillation amplitude is about 1.5 cm, which is the largest among all frequencies. In the East China Sea the amplitude is about 1.3 cm. The amplitude of the 6 years period in the Bohai Sea and Yellow Sea is the minimum, less than 1 cm.
2018, 40(3): 36-49.
doi: 10.3969/j.issn.0253-4193.2018.03.004
Abstract:
Based on the high-resolution multi-beam bathymetry and backscatter intensity data, this study calculated the morphological parameters of the seabed pockmarks in the North Yellow Sea and carried out quantitative analysis. Combined with the water depth, terrain slope and the back-scattering intensity data, the outline of the seabed pockmarks were accurately defined, and 282 pockmarks were identified which have circle, elliptic, or elongated shape in the plan view. By using ArcGIS software, the morphological parameters of the pockmarks were calculated and analyzed, the average long axis and short axis were 1.36 km and 0.78 km respectively, the average diameter were 0.94 km, average area and the average circumference were 0.88 km2 and 3.82 km, the pockmarks also have a aspect ratio of 1.83, average relief of 0.3 m to 2.5 m, and the average area concentration 13%, profile shapes of the pockmarks have W1, W2 and V type three categories, distributed in the north, south, and west of the pockmark group respectively. The large plane size but small vertical scale may be associated with the low concentration of the fluid, the external forces such as earthquake, tsunami or storm may also induced the formation as a trigger. The orientation of the major axis of the pockmarks aligned around ENE-WSW, NNE-SSW direction, consistent with the main direction of the bottom current in the study area. Some pockmarks string arranged along the same direction as the long axis, which shows that the development of the pockmarks may be controlled by the sedimentary strata as ancient river, or ancient lagoon etc. Acoustic backscatter strength of the area ranges from -60 dB to -71 dB, the data inside the pockmarks significantly higher than that of the outside, the average difference up to 5 dB, the high backscatter strength may attribute to the coarse sediments that left inside the pockmark due to winnowing of fine-grained sediments, or result of the precipitation of diagenitic or authigenic minerals associated with fluid venting.
Based on the high-resolution multi-beam bathymetry and backscatter intensity data, this study calculated the morphological parameters of the seabed pockmarks in the North Yellow Sea and carried out quantitative analysis. Combined with the water depth, terrain slope and the back-scattering intensity data, the outline of the seabed pockmarks were accurately defined, and 282 pockmarks were identified which have circle, elliptic, or elongated shape in the plan view. By using ArcGIS software, the morphological parameters of the pockmarks were calculated and analyzed, the average long axis and short axis were 1.36 km and 0.78 km respectively, the average diameter were 0.94 km, average area and the average circumference were 0.88 km2 and 3.82 km, the pockmarks also have a aspect ratio of 1.83, average relief of 0.3 m to 2.5 m, and the average area concentration 13%, profile shapes of the pockmarks have W1, W2 and V type three categories, distributed in the north, south, and west of the pockmark group respectively. The large plane size but small vertical scale may be associated with the low concentration of the fluid, the external forces such as earthquake, tsunami or storm may also induced the formation as a trigger. The orientation of the major axis of the pockmarks aligned around ENE-WSW, NNE-SSW direction, consistent with the main direction of the bottom current in the study area. Some pockmarks string arranged along the same direction as the long axis, which shows that the development of the pockmarks may be controlled by the sedimentary strata as ancient river, or ancient lagoon etc. Acoustic backscatter strength of the area ranges from -60 dB to -71 dB, the data inside the pockmarks significantly higher than that of the outside, the average difference up to 5 dB, the high backscatter strength may attribute to the coarse sediments that left inside the pockmark due to winnowing of fine-grained sediments, or result of the precipitation of diagenitic or authigenic minerals associated with fluid venting.
2018, 40(3): 50-61.
doi: 10.3969/j.issn.0253-4193.2018.03.005
Abstract:
To comprehend occurrence potential condition of submarine Quaternary freshwater resources in north Zhoushan sea area, Quaternary stratigraphic texture and sedimentary environment are analyzed based on drilling cores and high-resolution single-channel seismic profiles. Regularities of distribution of submarine loose sediment are elaborated. Extension and distribution of paleo-channels in middle and late Early-Pleistocene and early Early-Pleistocene form Shanghai land area and occurrence status of submarine Quaternary aquifer in the study sea area are discussed. The main exploitable Quaternary aquifers are the 4th confined aquifer in middle and late Early-Pleistocene and the 5th confined aquifer in early Early-Pleistocene. The water-abundance in the area of paleo-channels in the 4th confined aquifer is best, the confined aquifer with thick upper clay confining layer may be prone to reserving freshwater resources. The exploitable potential is classified into three types:better development prospect (type A), good development prospect (type B) and general development prospect (type C). The water-abundance in the area of paleo-channel in the 5th confined aquifer is also good, in which the reserving capacity and prospect of development and utilization are favorable.
To comprehend occurrence potential condition of submarine Quaternary freshwater resources in north Zhoushan sea area, Quaternary stratigraphic texture and sedimentary environment are analyzed based on drilling cores and high-resolution single-channel seismic profiles. Regularities of distribution of submarine loose sediment are elaborated. Extension and distribution of paleo-channels in middle and late Early-Pleistocene and early Early-Pleistocene form Shanghai land area and occurrence status of submarine Quaternary aquifer in the study sea area are discussed. The main exploitable Quaternary aquifers are the 4th confined aquifer in middle and late Early-Pleistocene and the 5th confined aquifer in early Early-Pleistocene. The water-abundance in the area of paleo-channels in the 4th confined aquifer is best, the confined aquifer with thick upper clay confining layer may be prone to reserving freshwater resources. The exploitable potential is classified into three types:better development prospect (type A), good development prospect (type B) and general development prospect (type C). The water-abundance in the area of paleo-channel in the 5th confined aquifer is also good, in which the reserving capacity and prospect of development and utilization are favorable.
2018, 40(3): 62-73.
doi: 10.3969/j.issn.0253-4193.2018.03.006
Abstract:
The Changjiang (Yangtze River) Estuary is a typical high-turbidity estuary, and Suspended Particulate Matter (SPM) in the Changjiang Estuary and its adjacent sea have large variation ranges of mass concentration, and show quite active and complicated behaviors there. SPM at 99 and 89 stations in this area was studied using OBS and LISST instruments in July 9-20, 2015 and in March 7-19, 2016, respectively, and parameters of turbidity, beam attenuation coefficient, floc total volume, mean size, and size spectrum of SPM were obtained from the two instruments. SPM mass concentration at surface, middle, and bottom layers of all stations were obtained after filtration, and δ13C(‰) values of particulate organic carbon (POC), δ15N(‰) values of particulate nitrogen (PN), and molecular ratios of POC/PN in SPM at typical stations were also obtained. The three parameters of turbidity, beam attenuation coefficient, and floc total volume all showed significant positive correlations with SPM mass concentration. Larger SPM mean sizes were generally found at bottom rather than at surface in the study area, and generally found in the dry season rather than in the flood season. The mean sizes of SPM released by the Changjiang freshwater were also much larger in March than in July. The SPM contents with similar size spectra could be further differentiated by their significantly different δ13C and δ15N values. The parameter of SPM mean effective density, calculated by mass concentration divided by floc total volume, can help elucidate the field depositing processes. The two parameters of SPM mean effective density and size showed significant negative correlations during both cruises. All the above results suggest that in March under the influence of strong vertical mixing, the Changjiang-originated SPM (with larger size, lower density and then lower depositing velocity) would be mixed with the resuspended sediments near the Changjiang mouth bar, and then transported as far as the eastern edge of the northern part of the study area. However in July, the Changjiang-originated SPM with smaller size, higher density and then higher depositing velocity would deposit rapidly near the river mouth.
The Changjiang (Yangtze River) Estuary is a typical high-turbidity estuary, and Suspended Particulate Matter (SPM) in the Changjiang Estuary and its adjacent sea have large variation ranges of mass concentration, and show quite active and complicated behaviors there. SPM at 99 and 89 stations in this area was studied using OBS and LISST instruments in July 9-20, 2015 and in March 7-19, 2016, respectively, and parameters of turbidity, beam attenuation coefficient, floc total volume, mean size, and size spectrum of SPM were obtained from the two instruments. SPM mass concentration at surface, middle, and bottom layers of all stations were obtained after filtration, and δ13C(‰) values of particulate organic carbon (POC), δ15N(‰) values of particulate nitrogen (PN), and molecular ratios of POC/PN in SPM at typical stations were also obtained. The three parameters of turbidity, beam attenuation coefficient, and floc total volume all showed significant positive correlations with SPM mass concentration. Larger SPM mean sizes were generally found at bottom rather than at surface in the study area, and generally found in the dry season rather than in the flood season. The mean sizes of SPM released by the Changjiang freshwater were also much larger in March than in July. The SPM contents with similar size spectra could be further differentiated by their significantly different δ13C and δ15N values. The parameter of SPM mean effective density, calculated by mass concentration divided by floc total volume, can help elucidate the field depositing processes. The two parameters of SPM mean effective density and size showed significant negative correlations during both cruises. All the above results suggest that in March under the influence of strong vertical mixing, the Changjiang-originated SPM (with larger size, lower density and then lower depositing velocity) would be mixed with the resuspended sediments near the Changjiang mouth bar, and then transported as far as the eastern edge of the northern part of the study area. However in July, the Changjiang-originated SPM with smaller size, higher density and then higher depositing velocity would deposit rapidly near the river mouth.
2018, 40(3): 74-85.
doi: 10.3969/j.issn.0253-4193.2018.03.007
Abstract:
With the technology development of basin simulation and geologic modeling, the study of hydrocarbon accumulation goes in quantitative, dynamic and 3D-visual direction. Combined with multi-dimension simulation of PetroMod software and data management of Petrel software, a technology platform called "multi-dimension, dynamic and visual" was constructed, and the technological process of spacial geologic modeling for exploration was built, which consisted of structure modeling, lithofacies modeling, parameter setting and model correction. By the former technology, the spacial geologic model of Baodao Sag in Qiongdongnan Basin was built in first time, while the dynamic and 3D-visual accumulation of southern fault terrace zone in deepwater was realized; finally, the spacial and dynamic accumulation process of southern fault terrace zone was restored on 4 critical periods. In conclusion, the earlier spatiotemporal relation was fine with smaller accumulation scale in southern fault terrace zone, and the later spatiotemporal relation was excellent with larger accumulation scale. In conclusion, the accumulation pattern in southern fault terrace zone could be described as hydrocarbon supplied by coal and neritic source rocks, migrated with faults, sand and ridges in stair shape, accumulated in large submarine fans, also compositely in multi-layers, the 3rd Lingshui member and the 1st Sanya member should be selected as the major layers, and the next exploration target will be the large reservoirs accumulated in multi-periods and multi-layers.
With the technology development of basin simulation and geologic modeling, the study of hydrocarbon accumulation goes in quantitative, dynamic and 3D-visual direction. Combined with multi-dimension simulation of PetroMod software and data management of Petrel software, a technology platform called "multi-dimension, dynamic and visual" was constructed, and the technological process of spacial geologic modeling for exploration was built, which consisted of structure modeling, lithofacies modeling, parameter setting and model correction. By the former technology, the spacial geologic model of Baodao Sag in Qiongdongnan Basin was built in first time, while the dynamic and 3D-visual accumulation of southern fault terrace zone in deepwater was realized; finally, the spacial and dynamic accumulation process of southern fault terrace zone was restored on 4 critical periods. In conclusion, the earlier spatiotemporal relation was fine with smaller accumulation scale in southern fault terrace zone, and the later spatiotemporal relation was excellent with larger accumulation scale. In conclusion, the accumulation pattern in southern fault terrace zone could be described as hydrocarbon supplied by coal and neritic source rocks, migrated with faults, sand and ridges in stair shape, accumulated in large submarine fans, also compositely in multi-layers, the 3rd Lingshui member and the 1st Sanya member should be selected as the major layers, and the next exploration target will be the large reservoirs accumulated in multi-periods and multi-layers.
2018, 40(3): 86-94.
doi: 10.3969/j.issn.0253-4193.2018.03.008
Abstract:
The neon flying squid Ommastrephes bartramii is a short-lived squid species, its suitable habitat is primarily dominated by the water temperature. In this study, the fishery data during 2006-2015 were obtained from the Chinese squid-jigging Science and Technology Group. Based on the relationship between the fishing effort and sea surface temperature (SST), we calculated the monthly proportion of favorable-SST area (PFSST) for O. bartramii, and further estimated the PFSST during 1985-2015. The decadal variability in the PFSST was examined and we also evaluated the influence of El Niño and La Niña events with different intensity on squid PFSST. Results suggested that the suitable SST for O. bartramii dramatically varied from month to month, corresponding to 16-19℃, 17-21℃, 15-19℃, 14-16℃ and 12-13℃, respectively, from July to November. The catch per unit effort (CPUE) varied with the PFSST, significantly positive correlation was found between them, suggesting that the PFSST on the fishing ground of O. bartramii increased, the CPUE would increase. The PFSST over 1985-2015 showed clearly monthly and interannual variability, which initially increased then decreased from July to November. Interannual variability of PFSST in July, August and September was basically the same, and similar interannual fluctuation in PFSST was found in October and November. Furthermore, significant positive relationship was found between the PFSST and SST on the fishing ground of O. bartramii during 1985-2015. The PFSST on the fishing ground of O. bartramii was greatly affected by the El Niño and La Niña events, but the influence varied with the intensity of each climatic event, which presented as:the SST under the weak La Niña event and normal climatic condition was the highest, the PFSST significantly increased; the SST under the Niña event with moderate and strong intensity was also high, however, the PFSST decreased. The SST under the El Niño events with weak, moderate and very strong intensity was low, while the PFSST for weak and very strong El Niño events was higher than that under the moderate El Niño event.
The neon flying squid Ommastrephes bartramii is a short-lived squid species, its suitable habitat is primarily dominated by the water temperature. In this study, the fishery data during 2006-2015 were obtained from the Chinese squid-jigging Science and Technology Group. Based on the relationship between the fishing effort and sea surface temperature (SST), we calculated the monthly proportion of favorable-SST area (PFSST) for O. bartramii, and further estimated the PFSST during 1985-2015. The decadal variability in the PFSST was examined and we also evaluated the influence of El Niño and La Niña events with different intensity on squid PFSST. Results suggested that the suitable SST for O. bartramii dramatically varied from month to month, corresponding to 16-19℃, 17-21℃, 15-19℃, 14-16℃ and 12-13℃, respectively, from July to November. The catch per unit effort (CPUE) varied with the PFSST, significantly positive correlation was found between them, suggesting that the PFSST on the fishing ground of O. bartramii increased, the CPUE would increase. The PFSST over 1985-2015 showed clearly monthly and interannual variability, which initially increased then decreased from July to November. Interannual variability of PFSST in July, August and September was basically the same, and similar interannual fluctuation in PFSST was found in October and November. Furthermore, significant positive relationship was found between the PFSST and SST on the fishing ground of O. bartramii during 1985-2015. The PFSST on the fishing ground of O. bartramii was greatly affected by the El Niño and La Niña events, but the influence varied with the intensity of each climatic event, which presented as:the SST under the weak La Niña event and normal climatic condition was the highest, the PFSST significantly increased; the SST under the Niña event with moderate and strong intensity was also high, however, the PFSST decreased. The SST under the El Niño events with weak, moderate and very strong intensity was low, while the PFSST for weak and very strong El Niño events was higher than that under the moderate El Niño event.
2018, 40(3): 95-101.
doi: 10.3969/j.issn.0253-4193.2018.03.009
Abstract:
For the issues that existed in the old streamline numerical integration procedure which used the fixed integrating-step, such as inaccurate calculation results and unnecessary calculations, literature 15 presented the adaptive-step based marine fluid flow streamline constructing algorithm (AMFCA). The adaptive-step integration model in AMFCA could use the local grid's flow direction and velocity at same time, and had the advantage of adjusting the integrating-step in two degrees of freedom. But the model also had several issues, such as the streamline tracking process interruption when the adjacent grids' flow direction changes rapidly, the calculation endless loop when the flow velocity is close to zero, and so on. In order to solve these problems, the paper gave a new adaptive-step integration optimization model. This new model kept all the advantages of the old model, and by limiting the integral step's lowest value, it resolved the front issues. In addition to this, through adjusted μ and δ's control ranges, the new model also made the applicability of integration step more widely,improved the computing efficiency, reduced the number of sampling data, and avoided the overlap and saw teeth of streamlines. Through many experiments and 3D simulating, it verified the practicability and feasibility of the new model.
For the issues that existed in the old streamline numerical integration procedure which used the fixed integrating-step, such as inaccurate calculation results and unnecessary calculations, literature 15 presented the adaptive-step based marine fluid flow streamline constructing algorithm (AMFCA). The adaptive-step integration model in AMFCA could use the local grid's flow direction and velocity at same time, and had the advantage of adjusting the integrating-step in two degrees of freedom. But the model also had several issues, such as the streamline tracking process interruption when the adjacent grids' flow direction changes rapidly, the calculation endless loop when the flow velocity is close to zero, and so on. In order to solve these problems, the paper gave a new adaptive-step integration optimization model. This new model kept all the advantages of the old model, and by limiting the integral step's lowest value, it resolved the front issues. In addition to this, through adjusted μ and δ's control ranges, the new model also made the applicability of integration step more widely,improved the computing efficiency, reduced the number of sampling data, and avoided the overlap and saw teeth of streamlines. Through many experiments and 3D simulating, it verified the practicability and feasibility of the new model.
2018, 40(3): 102-111.
doi: 10.3969/j.issn.0253-4193.2018.03.010
Abstract:
The sea surface features of internal waves in the Japan Sea are very complicated because of the special geographical location and topography. Remote sensing is an effective method for the detection of internal waves, and has been applied to the investigation of internal waves. In this paper, a study of internal waves in the Japan Sea with MODIS, GF-1 and ENVISAT ASAR data was presented. The distribution of internal waves in the Japan Sea was presented by extracting crests of internal waves. The crest length and propagation speed of internal waves were presented and amplitude inversion of internal waves in the Japan Sea were also conducted using the nonlinear Schrödinger (NLS) equation. The results demonstrated that internal waves in the Japan Sea shows broad distribution which mainly distributed in the zone of continental shelf and deep sea. The zone near the Japan Sea of 45°N where are fewer internal waves. A large number of small scale internal waves were detected in the continental shelf shallow of North Korea using GF-1 image. Internal waves in the southwest of Yamato Basin and Yamato Rise was not detected. The crest length of internal waves in the Japan Sea is usually more than 100 km, and the propagation speed of internal waves in the deep sea is greater than 1 m/s. The amplitude of internal waves in the continental shelf shallow is about 10 m, and it can be up to 60 m in the deep sea.
The sea surface features of internal waves in the Japan Sea are very complicated because of the special geographical location and topography. Remote sensing is an effective method for the detection of internal waves, and has been applied to the investigation of internal waves. In this paper, a study of internal waves in the Japan Sea with MODIS, GF-1 and ENVISAT ASAR data was presented. The distribution of internal waves in the Japan Sea was presented by extracting crests of internal waves. The crest length and propagation speed of internal waves were presented and amplitude inversion of internal waves in the Japan Sea were also conducted using the nonlinear Schrödinger (NLS) equation. The results demonstrated that internal waves in the Japan Sea shows broad distribution which mainly distributed in the zone of continental shelf and deep sea. The zone near the Japan Sea of 45°N where are fewer internal waves. A large number of small scale internal waves were detected in the continental shelf shallow of North Korea using GF-1 image. Internal waves in the southwest of Yamato Basin and Yamato Rise was not detected. The crest length of internal waves in the Japan Sea is usually more than 100 km, and the propagation speed of internal waves in the deep sea is greater than 1 m/s. The amplitude of internal waves in the continental shelf shallow is about 10 m, and it can be up to 60 m in the deep sea.
2018, 40(3): 112-120.
doi: 10.3969/j.issn.0253-4193.2018.03.011
Abstract:
A monthly sea surface temperature(SST)data from 1982 to 2015 of the South China Sea(SCS)was extracted based on the NOAA OISST data set in this study. First count up the SST at the Dongsha, Xisha and Nansha reef islands on time scale. Then the empirical orthogonal function(EOF)method was applied to the monthly anomaly field of the data set to analyze the characteristics of the yearly spatial and temporal variabilities of the SCS SST distribution. The study showed as follows:(1) The SST warming trends were differed at different reef areas. The rising trend of SST in the Dongsha reef area was the most significant(about 0.216℃/(10 a)). The following trends were 0.18℃/(10 a) at Xisha reef area and 0.096℃/(10 a) at Nansha reef area, respectively; (2) The SST in the Xisha and Nansha reef areas were in the optimum growth temperature of hermatypic corals in the whole year. There were about 4 months lower SST for hermatypic corals in the Dongsha reef area. The hottest month were focus on July(Dongsha), June(Xisha)and May(Nansha), respectively; (3) The first mode of EOF showed that SST over the SCS was spatially in phase and declined from northwest to southeast. That was Dongsha > Xisha > Nansha; (4) The first mode temporal distribution of EOF showed that the variation of SST in the SCS was related to the El Niño. The correlation analysis between SSTA over the SCS and the index of Niño3.4 showed that the average incidence was 0.655, and the highest correlation degree was 0.723. The SSTA over the SCS was lag of Niño3.4 about 7-8 months. In summary, under the background of global warming, the change of SST in the SCS is not only affected by the El Niño, but the continued rising is quietly threaten the growth of corals.
A monthly sea surface temperature(SST)data from 1982 to 2015 of the South China Sea(SCS)was extracted based on the NOAA OISST data set in this study. First count up the SST at the Dongsha, Xisha and Nansha reef islands on time scale. Then the empirical orthogonal function(EOF)method was applied to the monthly anomaly field of the data set to analyze the characteristics of the yearly spatial and temporal variabilities of the SCS SST distribution. The study showed as follows:(1) The SST warming trends were differed at different reef areas. The rising trend of SST in the Dongsha reef area was the most significant(about 0.216℃/(10 a)). The following trends were 0.18℃/(10 a) at Xisha reef area and 0.096℃/(10 a) at Nansha reef area, respectively; (2) The SST in the Xisha and Nansha reef areas were in the optimum growth temperature of hermatypic corals in the whole year. There were about 4 months lower SST for hermatypic corals in the Dongsha reef area. The hottest month were focus on July(Dongsha), June(Xisha)and May(Nansha), respectively; (3) The first mode of EOF showed that SST over the SCS was spatially in phase and declined from northwest to southeast. That was Dongsha > Xisha > Nansha; (4) The first mode temporal distribution of EOF showed that the variation of SST in the SCS was related to the El Niño. The correlation analysis between SSTA over the SCS and the index of Niño3.4 showed that the average incidence was 0.655, and the highest correlation degree was 0.723. The SSTA over the SCS was lag of Niño3.4 about 7-8 months. In summary, under the background of global warming, the change of SST in the SCS is not only affected by the El Niño, but the continued rising is quietly threaten the growth of corals.
2018, 40(3): 121-128.
doi: 10.3969/j.issn.0253-4193.2018.03.012
Abstract:
The method proposed by Lyzenga et al., due to its simplicity and effectiveness, has been widely applied to shallow-water bathymetry. However, this method is easy to underfit which will lead to low precision. We propose a modified model to improve the precision which will fit more correctly by amplifying the characteristic dimension and adding the degree of polynomial. We use the proposed model with WorldView-2 multispectral images and the measured 0-30 m water depth data to estimate the shallow water depth around the reef, and the 10-fold cross validation and residual analysis to validate the model. The results indicate that our model can improve the precision and is optimal using the degree of polynomial 3. At last, the water depth estimated by our model is used to calculate the terrain model around the reef, which can express the topographic feature intuitively and abundantly.
The method proposed by Lyzenga et al., due to its simplicity and effectiveness, has been widely applied to shallow-water bathymetry. However, this method is easy to underfit which will lead to low precision. We propose a modified model to improve the precision which will fit more correctly by amplifying the characteristic dimension and adding the degree of polynomial. We use the proposed model with WorldView-2 multispectral images and the measured 0-30 m water depth data to estimate the shallow water depth around the reef, and the 10-fold cross validation and residual analysis to validate the model. The results indicate that our model can improve the precision and is optimal using the degree of polynomial 3. At last, the water depth estimated by our model is used to calculate the terrain model around the reef, which can express the topographic feature intuitively and abundantly.
2018, 40(3): 129-140.
doi: 10.3969/j.issn.0253-4193.2018.03.013
Abstract:
Based on heavy mineral analysis of the shallow drilling (WHZK01) with a hole length of 25.1 m from the muddy area in the southern Weihai coast, the main mineral type of Core WHZK01 is hornblende (22.1%), magnetite (20.0%) and epidote (17.7%), three mineral assemblage units can be divided since the Late Pleistocene. (1) Fluvial facies (DU3, late MIS3) has a hornblende-epidote assemblage; (2) flood plain and estuarine faces (DU2, early MIS1) has a hornblende-epidote-ilmenite-limonite assemblage; (3) nearshore and shallow marine facies(DU1, Holocene) has a magnetite-epidote-micas-authigenic pyrite assemblage. Source identification indicates that the sediments of DU3 and DU2 are all from coastal rivers of the southern Shandong Peninsula. The sediments of DU1 are derived largely from the Yellow River transported by the coastal current, and are also influenced slightly by the coast rivers and island erosions.
Based on heavy mineral analysis of the shallow drilling (WHZK01) with a hole length of 25.1 m from the muddy area in the southern Weihai coast, the main mineral type of Core WHZK01 is hornblende (22.1%), magnetite (20.0%) and epidote (17.7%), three mineral assemblage units can be divided since the Late Pleistocene. (1) Fluvial facies (DU3, late MIS3) has a hornblende-epidote assemblage; (2) flood plain and estuarine faces (DU2, early MIS1) has a hornblende-epidote-ilmenite-limonite assemblage; (3) nearshore and shallow marine facies(DU1, Holocene) has a magnetite-epidote-micas-authigenic pyrite assemblage. Source identification indicates that the sediments of DU3 and DU2 are all from coastal rivers of the southern Shandong Peninsula. The sediments of DU1 are derived largely from the Yellow River transported by the coastal current, and are also influenced slightly by the coast rivers and island erosions.
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