Based on a comparison of synchronized temperature and salinity data collected in the eastern Qiongzhou Strait and at coastal marine stations, this study finds that, in summer, the variation in salinity near the Weizho...Based on a comparison of synchronized temperature and salinity data collected in the eastern Qiongzhou Strait and at coastal marine stations, this study finds that, in summer, the variation in salinity near the Weizhou Island in Guangxi is similar to that in the eastern and central portions of the Qiongzhou Strait. Additionally, the Beihai Station in Guangxi exhibits a small salinity variation, whereas the Longmen and Bailongwei Stations, both of which are located far from the Qiongzhou Strait, mainly exhibit continental hydrological characteristics in summer. Moreover, a comparison of the multi-year ocean current data from the Qiongzhou Strait and ocean current observations from the Weizhou Island Station and recently installed current-measuring stations shows that the residual current in the Qiongzhou Strait flows westward in winter and summer. The numerical simulation results also indicate that water from the eastern Qiongzhou Strait enters the Beibu Gulf. The characteristics of the temperature and salinity distributions and analyses of the residual currents further confirm that the western Guangdong coastal current is the main source of the westward transport of water in the Qiongzhou Strait. The primary driver of the formation of the western Guangdong coastal current is the westward flow of freshwater from the Zhujiang (Pearl) River. This water enters the Beibu Gulf via the Qiongzhou Strait and enhances the formation of the cyclonic circulation in the northern Beibu Gulf. In summer, the strong influence of the southwesterly wind leads to the formation of a strong northward coastal current along the western coast of the Beibu Gulf. This process promotes the transport of low-salinity diluted water toward the open ocean and the formation of larger- scale cyclonic circulation around Weizhou Island in the eastern Beibu Gulf. The results of this study regarding the effects of the water inflow from the eastern Qiongzhou Strait to the Beibu Gulf on the Guangxi coastal circulation directly challenge conventional conclusions concerning the transport direction of water through the Qiongzhou Strait in winter and summer.展开更多
In the present study, an existing three-dimensional finite volume computational ocean model （FVCOM） was refined and configured including an algorithm for computing the power density and mean power density at Qiongzh...In the present study, an existing three-dimensional finite volume computational ocean model （FVCOM） was refined and configured including an algorithm for computing the power density and mean power density at Qiongzhou Strait of China. The refined model was validated with the measured tidal levels and tidal currents at different gauging stations. The model results are in reasonable agreement with the measured data. Based on the modeling results, we assess the resource of the tidal stream energy in the Qiongzhou Strait and discuss the temporal and the spatial distribution of the tidal current energy there. The conclusion is extracted： the higher power density occurs in the middle area of the strait, and lower at both sides. Characteristics of power density such as the maximum possibility speed, maximum power density during the spring tide period and the neap tide period, have the similar distribution. The southeast part and central area of the strait are of rich tidal current energy, where the maximum possibility speed can reach to 4.6 m/s, and the maximum power density of the spring tide period and the neap tide period can reach 5 996 and 467 W/mz separately in the surface layer The annual mean power density can reach 819 W/m2. Statistical length of accumulative time of the velocity exceeding 0.7 m/s is about 4 717 h at local point during a year. The total theoretical tidal current energy resource is approximately 189.55 MW and the available exploited energy on present technology condition is 249, 20.2 and 263 GW/a separately by using the methods FLUX, FARM and GC in the Qiongzhou Strait.展开更多
We analyzed heavy metal concentrations in a number of surface sediments and cores from the Qiongzhou Strait and surrounding marine areas.The areas of high concentrations are primarily outside the eastern mouth of the ...We analyzed heavy metal concentrations in a number of surface sediments and cores from the Qiongzhou Strait and surrounding marine areas.The areas of high concentrations are primarily outside the eastern mouth of the Qiongzhou Strait and on the west side of the Leizhou Peninsula,whereas the areas of low concentrations are located primarily in the eastern Qiongzhou Strait.The maximum Cd,Pb and Zn concentrations in the samples collected in our study do not exceed the official standards for marine sediments,whereas the concentrations of Cr and Cu slightly exceed the standards.Correlations exist between the concentrations of Cu,Pb,Zn,Cr and Cd,and the concentrations of these metals are positively correlated with the mean particle size(φ value),indicating that the finer sediments have adsorbed greater amounts of heavy metal elements than the coarser sediments.An evaluation of the potential environmental risks demonstrates that certain indices of heavy metal pollution and environmental risks are relatively low and may be assigned low risk levels,thereby indicating that,in terms of heavy metals,the marine sedimentary environment in this region is only mildly impacted.Our analysis of the contaminant origins shows that the heavy metals in this region primarily originate in the Pearl River Estuary and that a small amount of them is derived from local runoff.The elevated heavy metal concentrations from the upper sections of the cores started 130 years ago,which indicats that heavy metals in the surface sediments are primarily due to human activities associated with industrialization.展开更多
Effects of currents on winter wind waves in the tide-dominated Qiongzhou Strait(QS)were numerically evaluated via employing the coupled ocean-atmosphere-wave-sediment transport(COAWST)modeling system.Validations showe...Effects of currents on winter wind waves in the tide-dominated Qiongzhou Strait(QS)were numerically evaluated via employing the coupled ocean-atmosphere-wave-sediment transport(COAWST)modeling system.Validations showed satisfactory model performance in simulating the intense tidal currents in the QS.Different effects of sea level variations and tidal currents on waves were examined under the maximum eastward(METC)and westward(MWTC)tidal currents.In the east entrance area of the QS,the positive sea levels under the MWTC deepened the water depth felt by waves,benefiting the further propagation of wave energy into the inner strait and causing increased wave height.The METC and the MWTC could both enhance the wave height in the east entrance area of the QS,mainly through current-induced convergence and wavenumber shift,respectively.By current-induced refraction,the METC(MWTC)triggered counterclockwise(clockwise)rotation in peak wave directions in the northern part of the QS while clockwise(counterclockwise)rotation in the southern part.展开更多
From the magnetotelluric detection in the epicentral region and the adjacent areas of the 1605 M7.5 Qiongzhou earthquake, we have discovered there is a low resistive body in the deep crust of the epicentral region. Th...From the magnetotelluric detection in the epicentral region and the adjacent areas of the 1605 M7.5 Qiongzhou earthquake, we have discovered there is a low resistive body in the deep crust of the epicentral region. The low resistive body extends straightly from the depth of about 13 km to the upper mantle, which is supposed as an uprising mantle pole. We therefore consider it is just the existing mantle pole and its upwelling thermal material that result in the faulting and stick-slipping activities of the upper crust, which is an important factor for the M7.5 Qiongzhou great earthquake occurrence. The postseismic faulting activity is characterized by creep, which shows that the risk is greatly decreased for the occurrence of a great earthquake with similar intensity in the future.展开更多
The spatial variation and diurnal fluctuation of sea surface wind over the Qiongzhou Strait were described using verified datasets from automatic weather stations on board a ferry, buoys, and on the coast. Results are...The spatial variation and diurnal fluctuation of sea surface wind over the Qiongzhou Strait were described using verified datasets from automatic weather stations on board a ferry, buoys, and on the coast. Results are as follows： （1） On average, sea surface wind speed is 34 m/s larger over the Qiongzhou Strait than in the coastal area. Sea surface wind speeds of 8.0 rrds or above （on Beaufort scale five） in the coastal area are associated with speeds 5-6 m/s greater over the surface of the Qiongzhou Strait. （2） Gust coefficients for the Qiongzhou Strait decrease along with increasing wind speeds. When coastal wind speed is less than scale five, the average gust coefficient over the sea surface is between 1.4 and 1.5; when wind speed is equal to scale five or above, the average gust coefficient is about 1.35. （3） In autumn and winter, the diurnal differences of average wind speed and wind consistency over the strait are less than those in the coastal area; when wind speed is 10.8 m/s （scale six） or above, the diurnal difference of average wind speed decreases while wind consistency increases for both the strait and the coast.展开更多
The velocity structure of the residual current across an entire section of the Qiongzhou Strait(QS) in summer is presented for the fi rst time. Shipboard Acoustic Doppler Current Profi le measurements, from the mid-re...The velocity structure of the residual current across an entire section of the Qiongzhou Strait(QS) in summer is presented for the fi rst time. Shipboard Acoustic Doppler Current Profi le measurements, from the mid-region of the QS(110.18°E), were collected on 1–4 August 2010. The diurnal tidal currents had their maximum amplitudes between 4.24 and 20.24 m. Their amplitude along the major axis ranged from approximately 0.55 m/s in the middle part of the strait(20.15°N) to 0.84 m/s in the north part of the strait(20.20°N). Both anticlockwise and clockwise tidal current rotations exist in the QS. During the observation period(neap tide), a signifi cant westward residual current occupied almost the entire study section. Two velocity cores of westward current were observed at the northern part and near the deepest trough, although an eastward current appeared in the middle part of the transect. The deepest core was located near 62 m at 20.13°N, with a maximum velocity of-0.34 m/s. The shallower core was located at approximately 16 m at 20.20°N, with a maximum velocity of-0.33 m/s. The estimated total volume of water transported through the QS was-0.16 Sv. This value is an important boundary condition, applicable to numerical models studying coastal ocean circulation in the northwestern South China Sea.展开更多
In this study,power spectral density and inverse analyses were performed to obtain the frequency characteristics and spatial distribution of temperature in the Qiongzhou Strait using reciprocal sound transmission data...In this study,power spectral density and inverse analyses were performed to obtain the frequency characteristics and spatial distribution of temperature in the Qiongzhou Strait using reciprocal sound transmission data obtained in a coastal acoustic tomo-graphy experiment conducted in 2013.The results reveal three dominant types of internal tides(diurnal,semidiurnal,and terdiurnal).Spectral analysis of the range-average temperature deviation along the northern and southern transmission paths shows that along the northern path,the energy of the diurnal internal tides was significantly larger than that of the semidiurnal tides.The semidiurnal internal tides,in contrast,were more pronounced along the southern path.A terdiurnal spectrum with an energy level equivalent to that of the semidiurnal internal tide was discernable for both the northern and southern paths.These three types of internal tides can also be recognized in the time variation of the zonal-average temperature deviation.The diurnal internal tides were strengthened along the northern coast,implying their westward propagation and the existence of coastally trapped effects.The other two types of internal tides,which have smaller wavelengths than the diurnal internal tides,were less resolved over the entire tomographic domain due to the insufficient resolution of the inversion.The data quality was verified to be satisfactory by error estimation.展开更多
The active period of the faults in the Qiongzhou Straits occurred principally in the Tertiary. The rupture zone is situated in the nearly E-W striking tectonic lowland between the Leizhou Peninsula and the Hainan Isla...The active period of the faults in the Qiongzhou Straits occurred principally in the Tertiary. The rupture zone is situated in the nearly E-W striking tectonic lowland between the Leizhou Peninsula and the Hainan Island, which was preformed by the southward and northward compressions due to the expansion of the South China Sea Basin. During the interglacial periods in the Quaternary, the lowland was inundated and deepened gradually due to erosion by sea curfent. It was until the last uprising of sea level during the postglacial period that the Qiongzhou Straits assumed its present appearance.展开更多
古海岸线重建能为理解全球气候变化和海陆格局演变提供重要的线索。笔者等基于钻孔资料重建了北部湾—雷琼地区新生代以来古海岸线变迁与琼州海峡演变过程。结果表明,北部湾—雷州半岛—海南岛(雷琼地区)新生代经历了古近纪北部湾古湖...古海岸线重建能为理解全球气候变化和海陆格局演变提供重要的线索。笔者等基于钻孔资料重建了北部湾—雷琼地区新生代以来古海岸线变迁与琼州海峡演变过程。结果表明,北部湾—雷州半岛—海南岛(雷琼地区)新生代经历了古近纪北部湾古湖、新近纪—早更新世早期古琼州海峡、早更新世晚期—晚更新世峡湾和全新世琼州海峡四个演化阶段。古近纪北部湾形成NEE向互不连通的断陷盆地并充填河—湖相沉积,渐新世晚期海水间歇性入侵北部湾古湖并连通孤立的断陷盆地;中新世早—中期(23.3~10.4 Ma)南海西北部海岸线快速后退,北部湾古湖演变为古琼州海峡,中新世晚期—上新世(10.4~2.58 Ma)海岸线继续后退形成宽阔的古琼州海峡,早更新世早期海退及火山喷发导致古琼州海峡萎缩;早更新世晚期—晚更新世气候频繁波动控制了峡湾与陆地的不断转化,而末次盛冰期大幅度海退直接导致北部湾—雷琼地区从海转陆;15~12 ka BP以来海岸线快速后退并在12~11 ka BP期间短暂停留,北部湾再次由陆转海,之后海平面继续上升,琼州海峡于11 ka BP自西向东完全打开,至6 ka BP海平面达到现今海平面以上2 m左右,现今海陆格局形成。展开更多
为研究中国气象局(China Meteorological Administration,CMA)研发的中国第一代全球再分析产品CRA(CMA Global Reanalysis)对海雾模拟的适用性,将CRA与欧洲中心再分析产品ERA5(the 5th Generation of ECMWF Reanalysis)以及美国国家环...为研究中国气象局(China Meteorological Administration,CMA)研发的中国第一代全球再分析产品CRA(CMA Global Reanalysis)对海雾模拟的适用性,将CRA与欧洲中心再分析产品ERA5(the 5th Generation of ECMWF Reanalysis)以及美国国家环境预报中心的再分析产品FNL(Final Reanalysis Data)分别作为WRF(Weather Research and Forecast)模式驱动的初边界条件,对发生在琼州海峡的一次持续性海雾过程进行数值模拟。结果表明:将3种再分析产品作为初始场均能模拟出琼州海峡海雾发展过程。CRA和ERA5模拟的海雾在偏东风下开始发展,风向转为东北风后消散。CRA模拟的海雾强度最强且维持时间最长,FNL模拟的底层风场较早转为东北风,海雾消散早。在垂直方向上,ERA5和CRA模拟的海雾发展高度与实况接近,FNL则明显偏低。CRA中较低的逆温层以及近地层温度将水汽聚集在低层,使得海雾可以持续发展并长时间维持。在加入实时更新的高分辨率海温后,模拟的气海温差场更精细,可反映出琼州海峡中部及东部气海温差小于0.5℃的区域,模拟海雾发展的能力更强。展开更多
利用中国第一代全球大气/陆面再分析产品(China’s first generation global atmospheric/land surface reanalysis product,简称CRA),结合地面自动站观测、中国气象局陆面数据同化系统的能见度格点数据、葵花8号卫星资料,分析了2021年1...利用中国第一代全球大气/陆面再分析产品(China’s first generation global atmospheric/land surface reanalysis product,简称CRA),结合地面自动站观测、中国气象局陆面数据同化系统的能见度格点数据、葵花8号卫星资料,分析了2021年1月21—26日琼州海峡一次持续性海雾过程的发展演变、环流形势以及边界层特征,同时分析了两种不同类型雾的形成机制。结果表明:(1)21—22日为低层冷空气扩散形成的锋面雾;23—26日为冷高后部偏东气流型平流雾过程,其中23日23:00至24日14:00大雾发展最强盛,连续12个时次出现特强浓雾,最小能见度达25 m。(2)锋面雾阶段,偏北风影响,风速为1~3 m/s;平流雾阶段,偏东风影响,风速为4~6 m/s。(3)锋面雾阶段,水汽辐合中心位于琼州海峡南岸至海南岛东北部陆地,大雾在陆地开始发展。平流雾阶段,水汽辐合中心位于琼州海峡北岸至海南岛东部海面一带,大雾自海上发展。(4)锋面雾阶段,逆温层在950 hPa左右高度发展,为下冷上暖的平流配置;平流雾阶段,950 hPa以下均为暖平流,逆温层从地面开始发展。大雾过程中锋面雾和平流雾两种不同性质大雾的发展使得大雾长时间维持。展开更多
基金The National Natural Science Foundation of China under contract No.41576024the Key Research and Development Program of Guangxi under contract No.AB16380282+1 种基金the Guangxi Key Laboratory of Marine Environmental Science Program under contract No.GXKLHY15-01the Fundamental Research Fund of Guangxi Academy of Sciences under contract No.2018YBJ301
文摘Based on a comparison of synchronized temperature and salinity data collected in the eastern Qiongzhou Strait and at coastal marine stations, this study finds that, in summer, the variation in salinity near the Weizhou Island in Guangxi is similar to that in the eastern and central portions of the Qiongzhou Strait. Additionally, the Beihai Station in Guangxi exhibits a small salinity variation, whereas the Longmen and Bailongwei Stations, both of which are located far from the Qiongzhou Strait, mainly exhibit continental hydrological characteristics in summer. Moreover, a comparison of the multi-year ocean current data from the Qiongzhou Strait and ocean current observations from the Weizhou Island Station and recently installed current-measuring stations shows that the residual current in the Qiongzhou Strait flows westward in winter and summer. The numerical simulation results also indicate that water from the eastern Qiongzhou Strait enters the Beibu Gulf. The characteristics of the temperature and salinity distributions and analyses of the residual currents further confirm that the western Guangdong coastal current is the main source of the westward transport of water in the Qiongzhou Strait. The primary driver of the formation of the western Guangdong coastal current is the westward flow of freshwater from the Zhujiang (Pearl) River. This water enters the Beibu Gulf via the Qiongzhou Strait and enhances the formation of the cyclonic circulation in the northern Beibu Gulf. In summer, the strong influence of the southwesterly wind leads to the formation of a strong northward coastal current along the western coast of the Beibu Gulf. This process promotes the transport of low-salinity diluted water toward the open ocean and the formation of larger- scale cyclonic circulation around Weizhou Island in the eastern Beibu Gulf. The results of this study regarding the effects of the water inflow from the eastern Qiongzhou Strait to the Beibu Gulf on the Guangxi coastal circulation directly challenge conventional conclusions concerning the transport direction of water through the Qiongzhou Strait in winter and summer.
基金The Chinese Marine Renewable Energy Special Fund under contract Nos GHME2012ZC05 and GHME2013ZC03
文摘In the present study, an existing three-dimensional finite volume computational ocean model （FVCOM） was refined and configured including an algorithm for computing the power density and mean power density at Qiongzhou Strait of China. The refined model was validated with the measured tidal levels and tidal currents at different gauging stations. The model results are in reasonable agreement with the measured data. Based on the modeling results, we assess the resource of the tidal stream energy in the Qiongzhou Strait and discuss the temporal and the spatial distribution of the tidal current energy there. The conclusion is extracted： the higher power density occurs in the middle area of the strait, and lower at both sides. Characteristics of power density such as the maximum possibility speed, maximum power density during the spring tide period and the neap tide period, have the similar distribution. The southeast part and central area of the strait are of rich tidal current energy, where the maximum possibility speed can reach to 4.6 m/s, and the maximum power density of the spring tide period and the neap tide period can reach 5 996 and 467 W/mz separately in the surface layer The annual mean power density can reach 819 W/m2. Statistical length of accumulative time of the velocity exceeding 0.7 m/s is about 4 717 h at local point during a year. The total theoretical tidal current energy resource is approximately 189.55 MW and the available exploited energy on present technology condition is 249, 20.2 and 263 GW/a separately by using the methods FLUX, FARM and GC in the Qiongzhou Strait.
基金supported by China’s Offshore Marine Comprehensive Survey and Evaluation Project and the Science and Technology Fund of the South China Sea Branch(No.1315)
文摘We analyzed heavy metal concentrations in a number of surface sediments and cores from the Qiongzhou Strait and surrounding marine areas.The areas of high concentrations are primarily outside the eastern mouth of the Qiongzhou Strait and on the west side of the Leizhou Peninsula,whereas the areas of low concentrations are located primarily in the eastern Qiongzhou Strait.The maximum Cd,Pb and Zn concentrations in the samples collected in our study do not exceed the official standards for marine sediments,whereas the concentrations of Cr and Cu slightly exceed the standards.Correlations exist between the concentrations of Cu,Pb,Zn,Cr and Cd,and the concentrations of these metals are positively correlated with the mean particle size(φ value),indicating that the finer sediments have adsorbed greater amounts of heavy metal elements than the coarser sediments.An evaluation of the potential environmental risks demonstrates that certain indices of heavy metal pollution and environmental risks are relatively low and may be assigned low risk levels,thereby indicating that,in terms of heavy metals,the marine sedimentary environment in this region is only mildly impacted.Our analysis of the contaminant origins shows that the heavy metals in this region primarily originate in the Pearl River Estuary and that a small amount of them is derived from local runoff.The elevated heavy metal concentrations from the upper sections of the cores started 130 years ago,which indicats that heavy metals in the surface sediments are primarily due to human activities associated with industrialization.
基金The Fund of Southern Marine Science and Engineering Guangdong Laboratory(Zhanjiang)under contract No.ZJW-2019-08the Program for Scientific Research Start-up Funds of Guangdong Ocean University under contract No.101302/R18001+1 种基金the National Natural Science Foundation of China under contract No.41776034the First-class Discipline Plan of Guangdong Province under contract No.CYL231419012。
文摘Effects of currents on winter wind waves in the tide-dominated Qiongzhou Strait(QS)were numerically evaluated via employing the coupled ocean-atmosphere-wave-sediment transport(COAWST)modeling system.Validations showed satisfactory model performance in simulating the intense tidal currents in the QS.Different effects of sea level variations and tidal currents on waves were examined under the maximum eastward(METC)and westward(MWTC)tidal currents.In the east entrance area of the QS,the positive sea levels under the MWTC deepened the water depth felt by waves,benefiting the further propagation of wave energy into the inner strait and causing increased wave height.The METC and the MWTC could both enhance the wave height in the east entrance area of the QS,mainly through current-induced convergence and wavenumber shift,respectively.By current-induced refraction,the METC(MWTC)triggered counterclockwise(clockwise)rotation in peak wave directions in the northern part of the QS while clockwise(counterclockwise)rotation in the southern part.
基金Joint Seismological Science Foundation of China (104123).
文摘From the magnetotelluric detection in the epicentral region and the adjacent areas of the 1605 M7.5 Qiongzhou earthquake, we have discovered there is a low resistive body in the deep crust of the epicentral region. The low resistive body extends straightly from the depth of about 13 km to the upper mantle, which is supposed as an uprising mantle pole. We therefore consider it is just the existing mantle pole and its upwelling thermal material that result in the faulting and stick-slipping activities of the upper crust, which is an important factor for the M7.5 Qiongzhou great earthquake occurrence. The postseismic faulting activity is characterized by creep, which shows that the risk is greatly decreased for the occurrence of a great earthquake with similar intensity in the future.
基金Research on the Pattern of gales over the Qiongzhou Strait and Forecasting Methods, a project of Natural Science Foundation of China (40765002)Forecasting System of Gales over the Qiongzhou Strait, a key science project for Hainan province (070302)
文摘The spatial variation and diurnal fluctuation of sea surface wind over the Qiongzhou Strait were described using verified datasets from automatic weather stations on board a ferry, buoys, and on the coast. Results are as follows： （1） On average, sea surface wind speed is 34 m/s larger over the Qiongzhou Strait than in the coastal area. Sea surface wind speeds of 8.0 rrds or above （on Beaufort scale five） in the coastal area are associated with speeds 5-6 m/s greater over the surface of the Qiongzhou Strait. （2） Gust coefficients for the Qiongzhou Strait decrease along with increasing wind speeds. When coastal wind speed is less than scale five, the average gust coefficient over the sea surface is between 1.4 and 1.5; when wind speed is equal to scale five or above, the average gust coefficient is about 1.35. （3） In autumn and winter, the diurnal differences of average wind speed and wind consistency over the strait are less than those in the coastal area; when wind speed is 10.8 m/s （scale six） or above, the diurnal difference of average wind speed decreases while wind consistency increases for both the strait and the coast.
基金Supported by the National Natural Science Foundation for Young Scientists of China(No.40806012)
文摘The velocity structure of the residual current across an entire section of the Qiongzhou Strait(QS) in summer is presented for the fi rst time. Shipboard Acoustic Doppler Current Profi le measurements, from the mid-region of the QS(110.18°E), were collected on 1–4 August 2010. The diurnal tidal currents had their maximum amplitudes between 4.24 and 20.24 m. Their amplitude along the major axis ranged from approximately 0.55 m/s in the middle part of the strait(20.15°N) to 0.84 m/s in the north part of the strait(20.20°N). Both anticlockwise and clockwise tidal current rotations exist in the QS. During the observation period(neap tide), a signifi cant westward residual current occupied almost the entire study section. Two velocity cores of westward current were observed at the northern part and near the deepest trough, although an eastward current appeared in the middle part of the transect. The deepest core was located near 62 m at 20.13°N, with a maximum velocity of-0.34 m/s. The shallower core was located at approximately 16 m at 20.20°N, with a maximum velocity of-0.33 m/s. The estimated total volume of water transported through the QS was-0.16 Sv. This value is an important boundary condition, applicable to numerical models studying coastal ocean circulation in the northwestern South China Sea.
基金This study was supported by the National Natural Science Foundation of China(Nos.41776107,41920104006,41906024,41906023,41806020,52071293,and 41976001)the Scientific Research Fund of SIO(Nos.JB2004,JZ2001 and JT1801)the Project of State Key Laboratory of Satellite Ocean Environment Dynamics,SIO(No.SOED ZZ2106).
文摘In this study,power spectral density and inverse analyses were performed to obtain the frequency characteristics and spatial distribution of temperature in the Qiongzhou Strait using reciprocal sound transmission data obtained in a coastal acoustic tomo-graphy experiment conducted in 2013.The results reveal three dominant types of internal tides(diurnal,semidiurnal,and terdiurnal).Spectral analysis of the range-average temperature deviation along the northern and southern transmission paths shows that along the northern path,the energy of the diurnal internal tides was significantly larger than that of the semidiurnal tides.The semidiurnal internal tides,in contrast,were more pronounced along the southern path.A terdiurnal spectrum with an energy level equivalent to that of the semidiurnal internal tide was discernable for both the northern and southern paths.These three types of internal tides can also be recognized in the time variation of the zonal-average temperature deviation.The diurnal internal tides were strengthened along the northern coast,implying their westward propagation and the existence of coastally trapped effects.The other two types of internal tides,which have smaller wavelengths than the diurnal internal tides,were less resolved over the entire tomographic domain due to the insufficient resolution of the inversion.The data quality was verified to be satisfactory by error estimation.
文摘The active period of the faults in the Qiongzhou Straits occurred principally in the Tertiary. The rupture zone is situated in the nearly E-W striking tectonic lowland between the Leizhou Peninsula and the Hainan Island, which was preformed by the southward and northward compressions due to the expansion of the South China Sea Basin. During the interglacial periods in the Quaternary, the lowland was inundated and deepened gradually due to erosion by sea curfent. It was until the last uprising of sea level during the postglacial period that the Qiongzhou Straits assumed its present appearance.
文摘古海岸线重建能为理解全球气候变化和海陆格局演变提供重要的线索。笔者等基于钻孔资料重建了北部湾—雷琼地区新生代以来古海岸线变迁与琼州海峡演变过程。结果表明,北部湾—雷州半岛—海南岛(雷琼地区)新生代经历了古近纪北部湾古湖、新近纪—早更新世早期古琼州海峡、早更新世晚期—晚更新世峡湾和全新世琼州海峡四个演化阶段。古近纪北部湾形成NEE向互不连通的断陷盆地并充填河—湖相沉积,渐新世晚期海水间歇性入侵北部湾古湖并连通孤立的断陷盆地;中新世早—中期(23.3~10.4 Ma)南海西北部海岸线快速后退,北部湾古湖演变为古琼州海峡,中新世晚期—上新世(10.4~2.58 Ma)海岸线继续后退形成宽阔的古琼州海峡,早更新世早期海退及火山喷发导致古琼州海峡萎缩;早更新世晚期—晚更新世气候频繁波动控制了峡湾与陆地的不断转化,而末次盛冰期大幅度海退直接导致北部湾—雷琼地区从海转陆;15~12 ka BP以来海岸线快速后退并在12~11 ka BP期间短暂停留,北部湾再次由陆转海,之后海平面继续上升,琼州海峡于11 ka BP自西向东完全打开,至6 ka BP海平面达到现今海平面以上2 m左右,现今海陆格局形成。
文摘为研究中国气象局(China Meteorological Administration,CMA)研发的中国第一代全球再分析产品CRA(CMA Global Reanalysis)对海雾模拟的适用性,将CRA与欧洲中心再分析产品ERA5(the 5th Generation of ECMWF Reanalysis)以及美国国家环境预报中心的再分析产品FNL(Final Reanalysis Data)分别作为WRF(Weather Research and Forecast)模式驱动的初边界条件,对发生在琼州海峡的一次持续性海雾过程进行数值模拟。结果表明:将3种再分析产品作为初始场均能模拟出琼州海峡海雾发展过程。CRA和ERA5模拟的海雾在偏东风下开始发展,风向转为东北风后消散。CRA模拟的海雾强度最强且维持时间最长,FNL模拟的底层风场较早转为东北风,海雾消散早。在垂直方向上,ERA5和CRA模拟的海雾发展高度与实况接近,FNL则明显偏低。CRA中较低的逆温层以及近地层温度将水汽聚集在低层,使得海雾可以持续发展并长时间维持。在加入实时更新的高分辨率海温后,模拟的气海温差场更精细,可反映出琼州海峡中部及东部气海温差小于0.5℃的区域,模拟海雾发展的能力更强。
