2016 Vol. 38, No. 5
Display Method:
2016, 38(5): .
Abstract:
2016, 38(5): 1-13.
doi: 10.3969/j.issn.0253-4193.2016.05.001
Abstract:
The Northwest Pacific model, a regional (1/20)°eddy-resolving ocean general circulation model, is adapted to study the seasonal and inter-annual variation of circulation and water exchange in the Luzon Strait (LS) based on the ROMS (Regional Oceanic Model System). The LS is the main channel, through which the SCS exchange water with the West Pacific Ocean. The seasonal variation in the Luzon Strait Transport (LST) is found to be significant; and LST is westward throughout the year. The LST through the 120.75°E Section reaches the minimum in June of 0.40×106 m3/s and maximum in December of 6.14×106 m3/s. The mean LST is estimated to be 3.04×106 m3/s. In the upper-layer (0-500 m), the Kuroshio Intrusion takes the shape of Kuroshio Loop with a South China Sea branch of Kuroshio in winter and autumn, while the Kuroshio Intrusion is non-significant with the disappearance of South China Sea branch of Kuroshio in spring and summer. In the deep-layer (>500 m), the southward current of LS is significant in winter and spring with 10 cm/s, while the current become weak in summer and fall. The Luzon Trench is the main channel through in the deep-layer. Multi-core structure is a characteristic of the vertical transport pattern in the LS, with several cores in its southern part and only one core in its northern part. The lag correlation coefficient with six months between LST and Niño 3.4 can reach to 41.6%, which is closely related to the remote influence of ENSO, and there are 2-3 years and 8 years cycle in the inter-annual variation of LST in addition.
The Northwest Pacific model, a regional (1/20)°eddy-resolving ocean general circulation model, is adapted to study the seasonal and inter-annual variation of circulation and water exchange in the Luzon Strait (LS) based on the ROMS (Regional Oceanic Model System). The LS is the main channel, through which the SCS exchange water with the West Pacific Ocean. The seasonal variation in the Luzon Strait Transport (LST) is found to be significant; and LST is westward throughout the year. The LST through the 120.75°E Section reaches the minimum in June of 0.40×106 m3/s and maximum in December of 6.14×106 m3/s. The mean LST is estimated to be 3.04×106 m3/s. In the upper-layer (0-500 m), the Kuroshio Intrusion takes the shape of Kuroshio Loop with a South China Sea branch of Kuroshio in winter and autumn, while the Kuroshio Intrusion is non-significant with the disappearance of South China Sea branch of Kuroshio in spring and summer. In the deep-layer (>500 m), the southward current of LS is significant in winter and spring with 10 cm/s, while the current become weak in summer and fall. The Luzon Trench is the main channel through in the deep-layer. Multi-core structure is a characteristic of the vertical transport pattern in the LS, with several cores in its southern part and only one core in its northern part. The lag correlation coefficient with six months between LST and Niño 3.4 can reach to 41.6%, which is closely related to the remote influence of ENSO, and there are 2-3 years and 8 years cycle in the inter-annual variation of LST in addition.
2016, 38(5): 14-26.
doi: 10.3969/j.issn.0253-4193.2016.05.002
Abstract:
Based on the CTD data of PN Section provided by Japanese Oceanographic Data Center, the current velocity of ninety cruises during 1991 to 2011 are calculated with dynamic height method. The structure, maximum velocity, flux and width of the current are analyzed. The results show that there are three kinds of typical current structure of Kuroshio at PN Section, which are single core structure, double-core structure and multi-core structure. The occurrence probability of single core, double-core and multi-core are 50%, 39% and 11% respectively. The current structure of Kuroshio at PN section exhibits significant seasonal variation. In autumn, the probability of occurrence of multi-core structure reaches its maximum, and the quarterly average of current core number is greater than other seasons. In winter, multi-core structure never emerges and single core structure occurs more often than any other structures, and the quarterly average of current core number is less than other seasons. All kinds of current structure occur in spring and summer. The quarterly average of current core number of spring and summer are between autumn and winter. The flux of Kuroshio at PN Section exhibits seasonal variation too. The flux reaches the largest in winter and summer, and smallest in autumn. Seasonal variation also occurs in maximum velocity and current width of Kuroshio at PN Section, which are the largest in summer and the smallest in autumn, followed by spring and winter.
Based on the CTD data of PN Section provided by Japanese Oceanographic Data Center, the current velocity of ninety cruises during 1991 to 2011 are calculated with dynamic height method. The structure, maximum velocity, flux and width of the current are analyzed. The results show that there are three kinds of typical current structure of Kuroshio at PN Section, which are single core structure, double-core structure and multi-core structure. The occurrence probability of single core, double-core and multi-core are 50%, 39% and 11% respectively. The current structure of Kuroshio at PN section exhibits significant seasonal variation. In autumn, the probability of occurrence of multi-core structure reaches its maximum, and the quarterly average of current core number is greater than other seasons. In winter, multi-core structure never emerges and single core structure occurs more often than any other structures, and the quarterly average of current core number is less than other seasons. All kinds of current structure occur in spring and summer. The quarterly average of current core number of spring and summer are between autumn and winter. The flux of Kuroshio at PN Section exhibits seasonal variation too. The flux reaches the largest in winter and summer, and smallest in autumn. Seasonal variation also occurs in maximum velocity and current width of Kuroshio at PN Section, which are the largest in summer and the smallest in autumn, followed by spring and winter.
2016, 38(5): 27-33.
doi: 10.3969/j.issn.0253-4193.2016.05.003
Abstract:
In this work, the growing and vanishing processes of the Qingdao Cold Water Mass (QCWM) were studied based on monthly mean climatological sea temperature data in the South Yellow Sea. And then, the extinction mechanism for QCWM was also examined using the meteorological data and the numerical simulation results in this study area. The results showed that the QCWM appears in March, has stable pattern in April, is biggest in its area in May, becomes small in its area in June and vanishes in July. During June to July, the strengthening of southerly winds and weakening of the anticyclonic eddy below the thermocline are the dynamic mechanism for the QCWM extinction, while the downward transfer of sea surface solar radiation and horizontal heat input are the thermodynamic mechanism of the QCWM extinction.
In this work, the growing and vanishing processes of the Qingdao Cold Water Mass (QCWM) were studied based on monthly mean climatological sea temperature data in the South Yellow Sea. And then, the extinction mechanism for QCWM was also examined using the meteorological data and the numerical simulation results in this study area. The results showed that the QCWM appears in March, has stable pattern in April, is biggest in its area in May, becomes small in its area in June and vanishes in July. During June to July, the strengthening of southerly winds and weakening of the anticyclonic eddy below the thermocline are the dynamic mechanism for the QCWM extinction, while the downward transfer of sea surface solar radiation and horizontal heat input are the thermodynamic mechanism of the QCWM extinction.
2016, 38(5): 34-45.
doi: 10.3969/j.issn.0253-4193.2016.05.004
Abstract:
With the launch of the Soil Moisture and Ocean Salinity (SMOS) and American Aquarius, different sea surface salinity (SSS) gridded products have been developed by several institutions, including SMOS Locean L3 data released by the Centre Aval de Traitement des Données SMOS (CATDS) in France, SMOS BEC L4 data released by the Barcelona Expert Centre (BEC) in Spain and Aquarius V3.0 CAP L3 data released by NASA Jet Propulsion Laboratory(JPL). Based on in situ salinity measurements, this paper assesses the performances of three satellite products on their accuracy and ability to depict ocean phenomena. The results show as follows: (1) In terms of accuracy of products, Aquarius CAP data are of best quality and have stable and low mean bias and RMSE, which have reached the design accuracy in some regions. The deviation of SMOS products is less stable, becoming abnormal in some months. SMOS products data are of relatively high quality in open ocean and low latitudes, but there are great errors in high latitudes, which needs further improvement. (2) The study of depicting physical phenomena shows that Aquarius data perform best in depicting the eastern edge of warm pool salinity front, SMOS BEC data take second place. SMOS Locean data are full of noise in the tropical Pacific, and describe the physical phenomena in poor performance.
With the launch of the Soil Moisture and Ocean Salinity (SMOS) and American Aquarius, different sea surface salinity (SSS) gridded products have been developed by several institutions, including SMOS Locean L3 data released by the Centre Aval de Traitement des Données SMOS (CATDS) in France, SMOS BEC L4 data released by the Barcelona Expert Centre (BEC) in Spain and Aquarius V3.0 CAP L3 data released by NASA Jet Propulsion Laboratory(JPL). Based on in situ salinity measurements, this paper assesses the performances of three satellite products on their accuracy and ability to depict ocean phenomena. The results show as follows: (1) In terms of accuracy of products, Aquarius CAP data are of best quality and have stable and low mean bias and RMSE, which have reached the design accuracy in some regions. The deviation of SMOS products is less stable, becoming abnormal in some months. SMOS products data are of relatively high quality in open ocean and low latitudes, but there are great errors in high latitudes, which needs further improvement. (2) The study of depicting physical phenomena shows that Aquarius data perform best in depicting the eastern edge of warm pool salinity front, SMOS BEC data take second place. SMOS Locean data are full of noise in the tropical Pacific, and describe the physical phenomena in poor performance.
2016, 38(5): 46-56.
doi: 10.3969/j.issn.0253-4193.2016.05.005
Abstract:
Sea surface salinity (SSS) from Aquarius during August 2011 and March 2014, together with in situ salinity data (e.g. Argo) are used to explore seasonal and interannual variations of the SSS in the Bay of Bengal. It shows that Aquarius SSS has a significant positive correlation with Argo SSS. The Aquarius SSS is relatively lower than Argo SSS, and there exists a negative bias of -0.13 between these two data. The negative bias is larger in the northern bay than that in the southern bay (-0.28 vs -0.10). The bias mainly comes from the different depth between Aquarius and Argo floats in measuring SSS. Aquarius SSS captures main seasonal variations of the SSS in the bay, such as the intrusion of saltier water from Arabian Sea and seasonal migrations of the freshwater plumes in the northern bay. Besides, the SSS reveals anomalous salting (freshening) in the bay during the spring 2011 (2012). Our results suggest that the reduced (enhanced) precipitation during the summer 2010 (2011) in the northern bay reduced (enhanced) freshening in that region, and the anomalous salting (freshening) water was advected southward by the surface-layer circulation causing anomalous salting (freshening) in the whole bay. Meanwhile, the positive (negative) wind stress curl anomaly also contribute to the anomalous salting (freshening) event during spring 2011 (2012) in the bay via impacting the vertical mixing processes.
Sea surface salinity (SSS) from Aquarius during August 2011 and March 2014, together with in situ salinity data (e.g. Argo) are used to explore seasonal and interannual variations of the SSS in the Bay of Bengal. It shows that Aquarius SSS has a significant positive correlation with Argo SSS. The Aquarius SSS is relatively lower than Argo SSS, and there exists a negative bias of -0.13 between these two data. The negative bias is larger in the northern bay than that in the southern bay (-0.28 vs -0.10). The bias mainly comes from the different depth between Aquarius and Argo floats in measuring SSS. Aquarius SSS captures main seasonal variations of the SSS in the bay, such as the intrusion of saltier water from Arabian Sea and seasonal migrations of the freshwater plumes in the northern bay. Besides, the SSS reveals anomalous salting (freshening) in the bay during the spring 2011 (2012). Our results suggest that the reduced (enhanced) precipitation during the summer 2010 (2011) in the northern bay reduced (enhanced) freshening in that region, and the anomalous salting (freshening) water was advected southward by the surface-layer circulation causing anomalous salting (freshening) in the whole bay. Meanwhile, the positive (negative) wind stress curl anomaly also contribute to the anomalous salting (freshening) event during spring 2011 (2012) in the bay via impacting the vertical mixing processes.
2016, 38(5): 57-69.
doi: 10.3969/j.issn.0253-4193.2016.05.006
Abstract:
Based on sea ice velocity and extent data provided by National Snow and Ice Data Center(NSIDC), kinematic characteristics of the Arctic sea ice from 1979 to 2012 was analyzed, as well as the relationship between sea ice motion and extent. With the high resolution sea surface pressure (SLP) and wind data from European Center for Medium-Range Weather Forecasts(ECMWF) and sea ice velocity data from NSIDC in 2007 and 2012, the effects of surface wind and sea level pressure on Arctic sea ice motion were also investigated. The results showed that the Arctic sea ice motion was accelerating with rate of 2.1%/a in winter and 1.7%/a in summer. In the Beaufort-Chukchi area and the Fram Strait area, the accelerating rates were 2.0%/a and 4.9%/a in winter, 1.6%/a and 2.2%/a in summer, respectively. There was a significant negative correlation between sea ice motion and sea ice extent, with a correlation coefficient was -0.77 from 1979 to 2012. The tendency of wind field in winter and summer was in accord with that of mean sea ice motion with correlation coefficients of 0.50 and 0.48, respectively. The influence of sea surface wind and sea level pressure on sea ice motion, divergence and redistribution was significant. From 234th to 273rd in summer of 2007, high pressure system controlled the Beaufort Sea, leading to southerly wind in Bering Strait and Chukchi Sea. As well as, the stronger Beaufort Gyre made sea ice detained in the central Arctic and the clockwise wind filed drove sea ice aggregate north of Greenland and Canadian Arctic Archipelago. In 2012, both the Bering Strait and the Chukchi Sea were at the junction of the low and high pressure systems, northerly wind during the same period as 2007. Under the joint action of low pressure and high pressure systems, sea ice was transported from the east towards west in the Arctic Ocean. The multiyear sea ice in the Canadian Basin was diverged driven by the offshore movement, and transported towards Chukchi Sea and increased the melting by the Pacific warm inflow.
Based on sea ice velocity and extent data provided by National Snow and Ice Data Center(NSIDC), kinematic characteristics of the Arctic sea ice from 1979 to 2012 was analyzed, as well as the relationship between sea ice motion and extent. With the high resolution sea surface pressure (SLP) and wind data from European Center for Medium-Range Weather Forecasts(ECMWF) and sea ice velocity data from NSIDC in 2007 and 2012, the effects of surface wind and sea level pressure on Arctic sea ice motion were also investigated. The results showed that the Arctic sea ice motion was accelerating with rate of 2.1%/a in winter and 1.7%/a in summer. In the Beaufort-Chukchi area and the Fram Strait area, the accelerating rates were 2.0%/a and 4.9%/a in winter, 1.6%/a and 2.2%/a in summer, respectively. There was a significant negative correlation between sea ice motion and sea ice extent, with a correlation coefficient was -0.77 from 1979 to 2012. The tendency of wind field in winter and summer was in accord with that of mean sea ice motion with correlation coefficients of 0.50 and 0.48, respectively. The influence of sea surface wind and sea level pressure on sea ice motion, divergence and redistribution was significant. From 234th to 273rd in summer of 2007, high pressure system controlled the Beaufort Sea, leading to southerly wind in Bering Strait and Chukchi Sea. As well as, the stronger Beaufort Gyre made sea ice detained in the central Arctic and the clockwise wind filed drove sea ice aggregate north of Greenland and Canadian Arctic Archipelago. In 2012, both the Bering Strait and the Chukchi Sea were at the junction of the low and high pressure systems, northerly wind during the same period as 2007. Under the joint action of low pressure and high pressure systems, sea ice was transported from the east towards west in the Arctic Ocean. The multiyear sea ice in the Canadian Basin was diverged driven by the offshore movement, and transported towards Chukchi Sea and increased the melting by the Pacific warm inflow.
2016, 38(5): 70-82.
doi: 10.3969/j.issn.0253-4193.2016.05.007
Abstract:
The rapid decrease of Arctic sea ice in summer makes shipping in the Arctic possible. The accurate sea ice forecasts are urgently required to well service the Arctic shipping activities. A numerical Arctic forecasting system was built based on MIT general circulation model (MITgcm) ice-ocean coupled model and the Nudging data assimilation method was applied into this model and assimilate the Advanced Microwave Scanning Radiometer 2 (AMSR2) sea ice concentration data. Three different kinds of Nudging assimilation schemes were firstly accessed and the results showed that all three nudging schemes can largely improve the initial sea ice concentration fields. For comparison, two forecasting experiments with and without Nudging assimilation but with the same forcing were designed to evaluate the role of nudging data assimilation. By comparing with the assimilated satellite-derived data and the ship-based in situ sea ice concentration observations, it was shown that the nudging assimilation significantly improved the 24-120 h sea ice concentration forecasts. The results showed that improvements occurred not only in the whole Arctic sea ice concentration forecasts, but also in the single point forecasts. The persistence forecasts performed better in 24-120 h forecast than Nudging experiments when sea ice chance little in August.
The rapid decrease of Arctic sea ice in summer makes shipping in the Arctic possible. The accurate sea ice forecasts are urgently required to well service the Arctic shipping activities. A numerical Arctic forecasting system was built based on MIT general circulation model (MITgcm) ice-ocean coupled model and the Nudging data assimilation method was applied into this model and assimilate the Advanced Microwave Scanning Radiometer 2 (AMSR2) sea ice concentration data. Three different kinds of Nudging assimilation schemes were firstly accessed and the results showed that all three nudging schemes can largely improve the initial sea ice concentration fields. For comparison, two forecasting experiments with and without Nudging assimilation but with the same forcing were designed to evaluate the role of nudging data assimilation. By comparing with the assimilated satellite-derived data and the ship-based in situ sea ice concentration observations, it was shown that the nudging assimilation significantly improved the 24-120 h sea ice concentration forecasts. The results showed that improvements occurred not only in the whole Arctic sea ice concentration forecasts, but also in the single point forecasts. The persistence forecasts performed better in 24-120 h forecast than Nudging experiments when sea ice chance little in August.
2016, 38(5): 83-95.
doi: 10.3969/j.issn.0253-4193.2016.05.008
Abstract:
By using the surface sensible heat flux data of ERA-interim reanalysis,we researched the inter-annual variability of spring Tibetan Plateau (TP) surface sensible heat flux (TPSH) during the period of 1981 to 2010 as well as its connection to the sea surface temperature over different oceans, and such connection may affect the precipitation of East China. The main conclusions are as follows: (1) the two main modes of TPSH inter-annual variability are well associated with Pacific and India Ocean sea surface temperature (SST) separately. The middle and eastern tropical Pacific SST anomaly are affected by winter (DJF) ENSO signal which can stimulate a westward and poleward wave train to change the precipitation anomaly over the southern TP. Through this process,a zonal dipole SH distribution is formed as the first mode with a periodicity of 5 a. On the other hand, an across equator wave train was excited by the spring India Ocean SSTA tripole pattern. It may cause the east wind anomaly over TP, weakening the Background Westerly, causing an opposite SH distribution between body region of TP and the surrounding area with a periodicity of 5 a to 7 a. (2) The influence of ENSO SSTA over Pacific Ocean and the SSTA tripole pattern over spring India Ocean combined with the two modes of TP spring SH to the precipitation of East China are synergistic and it is found that TP spring SH have greater effect to spring precipitation at middle and higher latitudes.
By using the surface sensible heat flux data of ERA-interim reanalysis,we researched the inter-annual variability of spring Tibetan Plateau (TP) surface sensible heat flux (TPSH) during the period of 1981 to 2010 as well as its connection to the sea surface temperature over different oceans, and such connection may affect the precipitation of East China. The main conclusions are as follows: (1) the two main modes of TPSH inter-annual variability are well associated with Pacific and India Ocean sea surface temperature (SST) separately. The middle and eastern tropical Pacific SST anomaly are affected by winter (DJF) ENSO signal which can stimulate a westward and poleward wave train to change the precipitation anomaly over the southern TP. Through this process,a zonal dipole SH distribution is formed as the first mode with a periodicity of 5 a. On the other hand, an across equator wave train was excited by the spring India Ocean SSTA tripole pattern. It may cause the east wind anomaly over TP, weakening the Background Westerly, causing an opposite SH distribution between body region of TP and the surrounding area with a periodicity of 5 a to 7 a. (2) The influence of ENSO SSTA over Pacific Ocean and the SSTA tripole pattern over spring India Ocean combined with the two modes of TP spring SH to the precipitation of East China are synergistic and it is found that TP spring SH have greater effect to spring precipitation at middle and higher latitudes.
2016, 38(5): 96-107.
doi: 10.3969/j.issn.0253-4193.2016.05.009
Abstract:
The depositional environment and sedimentary provenance were studied in the Prydz Bay based on mineralogical analysis of 33 surface sediment samples. Seventeen types of heavy minerals were recognized in this study. Garnet,hornblende and magnetite are the dominant heavy minerals,hypersthene and hematite are the characteristic minerals. From the distribution of the mineral assemblages,four mineral provinces can be identified. In Fram Bank mineral province (Province I),the garnet is treated as the main mineral and has the highest content of heavy mineral. In Prydz channel mineral province (Province II),the magnetite is treated as the diagnostic mineral,garnet and epidote take a dominant position of the minerals. In Four Ladies Bank province (Province Ⅲ) has significant content of hypersthene. In deep slope mineral province (Province Ⅳ),the main mineral is hornblende and the garnet is less than other provinces. The mineralogical characteristics of garnets from the study area shows that, the clastic garnet contains higher Fe,Mg element and lower Ca,Mn element,and mainly comes from senior granulite facies. Detrital mineral distribution characteristics is controlled by provenance,the current system and glacier activities such as a product of the combined action of multiple factors.
The depositional environment and sedimentary provenance were studied in the Prydz Bay based on mineralogical analysis of 33 surface sediment samples. Seventeen types of heavy minerals were recognized in this study. Garnet,hornblende and magnetite are the dominant heavy minerals,hypersthene and hematite are the characteristic minerals. From the distribution of the mineral assemblages,four mineral provinces can be identified. In Fram Bank mineral province (Province I),the garnet is treated as the main mineral and has the highest content of heavy mineral. In Prydz channel mineral province (Province II),the magnetite is treated as the diagnostic mineral,garnet and epidote take a dominant position of the minerals. In Four Ladies Bank province (Province Ⅲ) has significant content of hypersthene. In deep slope mineral province (Province Ⅳ),the main mineral is hornblende and the garnet is less than other provinces. The mineralogical characteristics of garnets from the study area shows that, the clastic garnet contains higher Fe,Mg element and lower Ca,Mn element,and mainly comes from senior granulite facies. Detrital mineral distribution characteristics is controlled by provenance,the current system and glacier activities such as a product of the combined action of multiple factors.
2016, 38(5): 108-123.
doi: 10.3969/j.issn.0253-4193.2016.05.010
Abstract:
A shallow drilling (ZK3) of 36.7 m long was accomplished for the comprehensive studies on granulometric analysis,AMS14C dating,foraminifera analysis in the Dalinghe estuary area. Combining with the data from five other engineering drillings,a typical stratigraphical sequence and a time-space comparison framework are roughly established for the estuary since the Late Pleistocene,showing sedimentary evolutions from fluvial to limnetic to littoral/estuarine to shallow sea and then to deltaic environments in this area. This study reveals that marine environments began to prevail in the Dalinghe Estuary area at about 8 500 cal a BP,and evolved into deltaic one after 4 000 cal a BP; the sea level changes since the Late Pleistocene was the main factor controlling the sedimentation and environmental evolutions in the Dalinghe Estuary; Dalinghe may plays an important role for the development and evolution of the modern Liaohe Delta.
A shallow drilling (ZK3) of 36.7 m long was accomplished for the comprehensive studies on granulometric analysis,AMS14C dating,foraminifera analysis in the Dalinghe estuary area. Combining with the data from five other engineering drillings,a typical stratigraphical sequence and a time-space comparison framework are roughly established for the estuary since the Late Pleistocene,showing sedimentary evolutions from fluvial to limnetic to littoral/estuarine to shallow sea and then to deltaic environments in this area. This study reveals that marine environments began to prevail in the Dalinghe Estuary area at about 8 500 cal a BP,and evolved into deltaic one after 4 000 cal a BP; the sea level changes since the Late Pleistocene was the main factor controlling the sedimentation and environmental evolutions in the Dalinghe Estuary; Dalinghe may plays an important role for the development and evolution of the modern Liaohe Delta.
2016, 38(5): 124-132.
doi: 10.3969/j.issn.0253-4193.2016.05.011
Abstract:
Groundwater monitoring combined with mathematical analysis is the main method of groundwater dynamics studies. But there is less monitoring data for submarine groundwater than inland groundwater in the most coastal areas. In this study, sea drillings ZK03, ZK08 were designed to real-time monitor dynamics characteristic of submarine groundwater in multi-layers aquifers and ocean tides. Combined with stratum structure and sedimentary evolution setting, the paper analyzed the dynamic characteristics of submarine groundwater in the Laizhou Bay and revealed the driving mechanism. The results showed that submarine groundwater dynamic appeared to be periodic and stratified in the Laizhou Bay, Holocene aquifer were closely associated with the sea, where the vertical thickness of seawater intrusion interface was about 10 m. Submarine groundwater stratification were roughly consistent with sedimentary strata. Controlled by strata structure and sedimentary environment, the mixing process in different aquifer groundwater or between groundwater and seawater drived by precipitation, groundwater runoff and tide was the main driving mechanism of submarine groundwater dynamic. Then the paper constructed a preliminary submarine groundwater distribution pattern to explore the interaction between groundwater and seawater. The study on the dynamics characteristic of submarine groundwater in the Laizhou Bay play a positive role in analyzing saltwater interface change mechanism and exploring the submarine groundwater discharge.
Groundwater monitoring combined with mathematical analysis is the main method of groundwater dynamics studies. But there is less monitoring data for submarine groundwater than inland groundwater in the most coastal areas. In this study, sea drillings ZK03, ZK08 were designed to real-time monitor dynamics characteristic of submarine groundwater in multi-layers aquifers and ocean tides. Combined with stratum structure and sedimentary evolution setting, the paper analyzed the dynamic characteristics of submarine groundwater in the Laizhou Bay and revealed the driving mechanism. The results showed that submarine groundwater dynamic appeared to be periodic and stratified in the Laizhou Bay, Holocene aquifer were closely associated with the sea, where the vertical thickness of seawater intrusion interface was about 10 m. Submarine groundwater stratification were roughly consistent with sedimentary strata. Controlled by strata structure and sedimentary environment, the mixing process in different aquifer groundwater or between groundwater and seawater drived by precipitation, groundwater runoff and tide was the main driving mechanism of submarine groundwater dynamic. Then the paper constructed a preliminary submarine groundwater distribution pattern to explore the interaction between groundwater and seawater. The study on the dynamics characteristic of submarine groundwater in the Laizhou Bay play a positive role in analyzing saltwater interface change mechanism and exploring the submarine groundwater discharge.
2016, 38(5): 133-140.
doi: 10.3969/j.issn.0253-4193.2016.05.012
Abstract:
Different Multifractal spectrum can be used for petroleum prospect evaluation. A typical multifractal model called the method of moments is employed to study the distribution patterns based on the multifractal spectrum forms obtained from 13 oil and gas indexes and 2 684 data in the deepwater area of central canyon of the Qiongdongnan basin. The results show that the indicators with strong multi-fractal characteristics in deepwater have wide and continuous fractal spectrum function features, forming a right side arc shape. While other indicators display weak or single fractal feature. Comparing the result with the one from factor analysis, shows that these results are generally consistent. In order to further examine the weights of these oil and gas indexes, principal component analysis was used to analyze these indicators. The results indicate that isobutane, normal butane, iso-pentane is important indicators to delineate hydrocarbon in the deepwater area.
Different Multifractal spectrum can be used for petroleum prospect evaluation. A typical multifractal model called the method of moments is employed to study the distribution patterns based on the multifractal spectrum forms obtained from 13 oil and gas indexes and 2 684 data in the deepwater area of central canyon of the Qiongdongnan basin. The results show that the indicators with strong multi-fractal characteristics in deepwater have wide and continuous fractal spectrum function features, forming a right side arc shape. While other indicators display weak or single fractal feature. Comparing the result with the one from factor analysis, shows that these results are generally consistent. In order to further examine the weights of these oil and gas indexes, principal component analysis was used to analyze these indicators. The results indicate that isobutane, normal butane, iso-pentane is important indicators to delineate hydrocarbon in the deepwater area.
2016, 38(5): 141-149.
doi: 10.3969/j.issn.0253-4193.2016.05.013
Abstract:
An improved second-order numerical model for wave bottom boundary layer is developed, which includes both effects of wave Reynolds stress and mean horizontal pressure gradient. The simulated instantaneous velocity profiles, oscillatory velocity amplitudes and mean velocity profiles in the laminar boundary layer beneath shoaling waves are in good agreements with the experimental data. Effects of various dynamic processes on the mean velocity distribution are discussed. Results reveal that the mean velocity is directed onshore and offshore in the lower and upper regions of the bottom boundary layer, respectively, and this pattern becomes increasing obvious as wave shoals over a sloping bed. The near-bed onshore mean velocity is dominated by wave Reynolds stress related to the second-order advective terms, while the offshore mean velocity in the upper region is mostly due to the mean horizontal pressure gradient related to the undertow current.
An improved second-order numerical model for wave bottom boundary layer is developed, which includes both effects of wave Reynolds stress and mean horizontal pressure gradient. The simulated instantaneous velocity profiles, oscillatory velocity amplitudes and mean velocity profiles in the laminar boundary layer beneath shoaling waves are in good agreements with the experimental data. Effects of various dynamic processes on the mean velocity distribution are discussed. Results reveal that the mean velocity is directed onshore and offshore in the lower and upper regions of the bottom boundary layer, respectively, and this pattern becomes increasing obvious as wave shoals over a sloping bed. The near-bed onshore mean velocity is dominated by wave Reynolds stress related to the second-order advective terms, while the offshore mean velocity in the upper region is mostly due to the mean horizontal pressure gradient related to the undertow current.
2016, 38(5): 150-157.
doi: 10.3969/j.issn.0253-4193.2016.05.014
Abstract:
Automatic extraction of the side-scan sonar imagery outlines is difficult. The results extracted by edge detection based on sharp gray-scale gradient of image are discontinuous and rough, and also have gaps and holes edge detection. After preprocessing the side-scan sonar image and thresholding, some processings are carried out to take the smooth and continuous rims of the geological objectives, and to eliminate the background noises, by measuring and extracting the corresponding shape from the image with a certain form of structural element according to the basic idea of mathematical morphology. The algorithm of feature extraction for the side-scan sonar imagery based on mathematical morphology is as follows: firstly, preprocess the image and do thresholding it; then process the image by mathematical morphology; finally obtained the edges of the geological objectives by edge-detection technology. The numerical experiments show that this method leads to smooth and continuous and accurate detection, meanwhile, greatly reduced background noise.
Automatic extraction of the side-scan sonar imagery outlines is difficult. The results extracted by edge detection based on sharp gray-scale gradient of image are discontinuous and rough, and also have gaps and holes edge detection. After preprocessing the side-scan sonar image and thresholding, some processings are carried out to take the smooth and continuous rims of the geological objectives, and to eliminate the background noises, by measuring and extracting the corresponding shape from the image with a certain form of structural element according to the basic idea of mathematical morphology. The algorithm of feature extraction for the side-scan sonar imagery based on mathematical morphology is as follows: firstly, preprocess the image and do thresholding it; then process the image by mathematical morphology; finally obtained the edges of the geological objectives by edge-detection technology. The numerical experiments show that this method leads to smooth and continuous and accurate detection, meanwhile, greatly reduced background noise.
2016, 38(5): 158-167.
doi: 10.3969/j.issn.0253-4193.2016.05.015
Abstract:
Suspended sediment concentration (SSC) is an important environmental index of muddy coasts. To understand the response of the suspended sediment concentration and suspended sediment transport on tidal flat to a certain storm event, we carried out in situ measurements of water depth, wave height, near-bed velocity and SSC profiles in high resolution on an intertidal mudflat of Nanhui Spit, which is on the delta front of the Yangtze River, China. The measurements last for 9 tidal cycles, covering pre-, intra-and post-"Fung-wong" typhoon. The results show that: (1) mean and max wave heights, bed shear stress , SSC and suspended sediment transport rate during storm condition were several times higher than those in calm weather; (2) in storm condition, a fluid mud layer (SSC>10 g/L) in the thickness of tens of centimeters developed during slack water at high tides, resulting from settling of suspended sediment. We conclude that the drastic variation of suspended sediment concentration in muddy coastal areas is caused by enhanced energy in the water column caused by storm, leading to increasing combined wave-current bed shear stress, which leads to bed sediment resuspension.
Suspended sediment concentration (SSC) is an important environmental index of muddy coasts. To understand the response of the suspended sediment concentration and suspended sediment transport on tidal flat to a certain storm event, we carried out in situ measurements of water depth, wave height, near-bed velocity and SSC profiles in high resolution on an intertidal mudflat of Nanhui Spit, which is on the delta front of the Yangtze River, China. The measurements last for 9 tidal cycles, covering pre-, intra-and post-"Fung-wong" typhoon. The results show that: (1) mean and max wave heights, bed shear stress , SSC and suspended sediment transport rate during storm condition were several times higher than those in calm weather; (2) in storm condition, a fluid mud layer (SSC>10 g/L) in the thickness of tens of centimeters developed during slack water at high tides, resulting from settling of suspended sediment. We conclude that the drastic variation of suspended sediment concentration in muddy coastal areas is caused by enhanced energy in the water column caused by storm, leading to increasing combined wave-current bed shear stress, which leads to bed sediment resuspension.
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