Using the 25-h continuing hydrographic observations at three successive stations in February 2012 and the mooring time series of current observations from January to March 2015,the tidal currents and tidal energy flux...Using the 25-h continuing hydrographic observations at three successive stations in February 2012 and the mooring time series of current observations from January to March 2015,the tidal currents and tidal energy fluxes in the coastal waters east of Hainan Island in the northwestern South China Sea were analyzed.The diurnal and semidiurnal(using K_(1) and M_(2) as proxies,respectively)tidal currents and associated isopycnal undulations were derived with harmonic analysis.Results show that the velocities of the diurnal and semidiurnal tides derived from the 25-h observations are comparable to those from the mooring series.The semi-major axes of the tidal ellipses were O(4-7 cm/s)for barotropic tides and O(2-4 cm/s)for baroclinic tides.The directions were in NE-SW at deeper stations to N-S at the shallowest station for the diurnal tide and from NW-SE to NE-SW for the semidiurnal tide.Both the diurnal and semidiurnal isopycnal fl uctuations reached O(5 m),O(8 m),and O(10 m)at the cross-shelf stations(H03,H04,and H05)from 35 m,45 m,to 55 m,respectively,showing insignifi cant vertical variation,and the barotropic signals were predominate.The baroclinic diurnal tide showed fi rst-mode structures at H03-05,as does the semidiurnal tide at H03.The semidiurnal tide at H04 and H05 exhibited higher-mode structures.The time series of both the alongshore and cross-shore components reveal the vertically propagation features of the baroclinic tidal phase and energy.The calculated horizontal energy fl uxes of the diurnal and semidiurnal internal tides decreased from O(0.1 W/m)at H05 to O(0.01 W/m)at H03,implying a propagation and dissipation of energy from off shore to inshore.展开更多
The Mudui stratigraphic section represents the typical records of sedimentation processes of sand dunes and interdune depressions on the east coast of Hainan Island.Based on high-density sampling and optically stimula...The Mudui stratigraphic section represents the typical records of sedimentation processes of sand dunes and interdune depressions on the east coast of Hainan Island.Based on high-density sampling and optically stimulated luminescence(OSL) dating of the strata of the section,the grain-size composition,grain-size parameters,cumulative distribution probability curve,and grain-size-sensitivity indexes(SC/D) were analyzed.The analyzed results show that the grain-size features of aeolian sand,weakly developed sandy paleosol,two-facies(aeolian and aqueous) deposits,and lagoon deposits are all different.This indicates four evolutionary phases of the sedimentary environment of the east coast of Hainan Island since 38 ka B.P.Phase I:38-22 ka B.P.;phase II:22-17 ka B.P.;phase III:17-10 ka B.P.;phase IV:10 ka B.P.-present.The climate experienced the hot-wet/hot-dry,hot-wet/hot-dry,and warm-wet/hot-wet fluctuations,and the sedimentary environment also underwent lagoon deposition,dune and interdune depression deposition,dune stabilization and soil development,shifting sand deposition,and evolutionary processes.展开更多
Material fluxes （e.g., nutrients） from coastal waters to offshore areas play an important role in controlling the water quality of the adjacent sea areas not only by increasing nutrient concentration hut also by cha...Material fluxes （e.g., nutrients） from coastal waters to offshore areas play an important role in controlling the water quality of the adjacent sea areas not only by increasing nutrient concentration hut also by changing nutrient structures. In this study, naturally occurring isotopes, ^226Ra and ^228Ra, were measured with the alpha spectrometry in the Wenjiao-Wenchang and Wanquan estuaries and adjacent sea areas along the east coast of Hainan Island. The excess ^226Ra and ^228Ra activities were observed by comparison with the values derived from the conservative mixing of freshwater and seawater end-members in both estuaries. Using a one-dimensional diffusion model, the horizontal eddy diffusion coefficient of 3.1 6 × 10^5 cm^2/s, for nutrients diffusing from their sources, was derived from 228Ra activities. Consequently, the corresponding nutrient fluxes flowing into the coastal waters were assessed. The results can provide useful information for the study of the mixing and exchange processes of coastal waters as well as dissoluble pollutant transport in this sea area.展开更多
Marginal water east of the Hainan Island is where internal waves occur frequently. Few studies have been conducted on these internal waves so far, and their formation mechanism remains unclear. In this study, the auth...Marginal water east of the Hainan Island is where internal waves occur frequently. Few studies have been conducted on these internal waves so far, and their formation mechanism remains unclear. In this study, the author uses the China-Brazil Earth Resources Satellite data (CBERS) to detect and calculate the distribution, direction, wavelength and amplitude of internal waves in this area. The results show that the direction of these internal waves is offshore and their wavelength is about 150-200 m. The internal waves can be postulated as formed by upwelling or reversed tide.展开更多
基金Supported by the National Nature Science Foundation of China(Nos.41776034,41506018,41706025,41706129)the First-Class Discipline Plan of Guangdong Province(Nos.CYL231419012,231819002)+4 种基金the Matched Grant of Guangdong Ocean University(No.P15299)the PhD Start-up Grant of Guangdong Ocean University(No.R20022)the Project of Enhancing School with Innovation of Guangdong University(No.Q16303)the Project of Enhancing School with Innovation of Education Department of Guangdong Province(Nos.2018KQNCX082,2019KCXTF021)the Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(No.GML2019ZD0303)。
文摘Using the 25-h continuing hydrographic observations at three successive stations in February 2012 and the mooring time series of current observations from January to March 2015,the tidal currents and tidal energy fluxes in the coastal waters east of Hainan Island in the northwestern South China Sea were analyzed.The diurnal and semidiurnal(using K_(1) and M_(2) as proxies,respectively)tidal currents and associated isopycnal undulations were derived with harmonic analysis.Results show that the velocities of the diurnal and semidiurnal tides derived from the 25-h observations are comparable to those from the mooring series.The semi-major axes of the tidal ellipses were O(4-7 cm/s)for barotropic tides and O(2-4 cm/s)for baroclinic tides.The directions were in NE-SW at deeper stations to N-S at the shallowest station for the diurnal tide and from NW-SE to NE-SW for the semidiurnal tide.Both the diurnal and semidiurnal isopycnal fl uctuations reached O(5 m),O(8 m),and O(10 m)at the cross-shelf stations(H03,H04,and H05)from 35 m,45 m,to 55 m,respectively,showing insignifi cant vertical variation,and the barotropic signals were predominate.The baroclinic diurnal tide showed fi rst-mode structures at H03-05,as does the semidiurnal tide at H03.The semidiurnal tide at H04 and H05 exhibited higher-mode structures.The time series of both the alongshore and cross-shore components reveal the vertically propagation features of the baroclinic tidal phase and energy.The calculated horizontal energy fl uxes of the diurnal and semidiurnal internal tides decreased from O(0.1 W/m)at H05 to O(0.01 W/m)at H03,implying a propagation and dissipation of energy from off shore to inshore.
文摘The Mudui stratigraphic section represents the typical records of sedimentation processes of sand dunes and interdune depressions on the east coast of Hainan Island.Based on high-density sampling and optically stimulated luminescence(OSL) dating of the strata of the section,the grain-size composition,grain-size parameters,cumulative distribution probability curve,and grain-size-sensitivity indexes(SC/D) were analyzed.The analyzed results show that the grain-size features of aeolian sand,weakly developed sandy paleosol,two-facies(aeolian and aqueous) deposits,and lagoon deposits are all different.This indicates four evolutionary phases of the sedimentary environment of the east coast of Hainan Island since 38 ka B.P.Phase I:38-22 ka B.P.;phase II:22-17 ka B.P.;phase III:17-10 ka B.P.;phase IV:10 ka B.P.-present.The climate experienced the hot-wet/hot-dry,hot-wet/hot-dry,and warm-wet/hot-wet fluctuations,and the sedimentary environment also underwent lagoon deposition,dune and interdune depression deposition,dune stabilization and soil development,shifting sand deposition,and evolutionary processes.
基金supported by the Natural Science Foundation of China (Grant No.41021064)the Sino-German Cooperation Project of Ministry of Science and Technology of China (Grant No.2007DFB20380)the Ph. D. Program Scholarship Fund of East China Normal University (Grant No.2010047)
文摘Material fluxes （e.g., nutrients） from coastal waters to offshore areas play an important role in controlling the water quality of the adjacent sea areas not only by increasing nutrient concentration hut also by changing nutrient structures. In this study, naturally occurring isotopes, ^226Ra and ^228Ra, were measured with the alpha spectrometry in the Wenjiao-Wenchang and Wanquan estuaries and adjacent sea areas along the east coast of Hainan Island. The excess ^226Ra and ^228Ra activities were observed by comparison with the values derived from the conservative mixing of freshwater and seawater end-members in both estuaries. Using a one-dimensional diffusion model, the horizontal eddy diffusion coefficient of 3.1 6 × 10^5 cm^2/s, for nutrients diffusing from their sources, was derived from 228Ra activities. Consequently, the corresponding nutrient fluxes flowing into the coastal waters were assessed. The results can provide useful information for the study of the mixing and exchange processes of coastal waters as well as dissoluble pollutant transport in this sea area.
基金supported by the Project of Knowledge Innovation of Chinese Academy of Sciences (KZCX1-YW-12-01)863(2008AA09Z112)+3 种基金National Natural Sciences Foundation of China(40876092)Program of Guangdong Provincial Science &Technology(2008B030303026)Natural Sciences Foundation of Guangdong Province(8351030101000002)Project of Knowledge Innovation of South China Sea Institute of Oceanology(LYQY200701)
文摘Marginal water east of the Hainan Island is where internal waves occur frequently. Few studies have been conducted on these internal waves so far, and their formation mechanism remains unclear. In this study, the author uses the China-Brazil Earth Resources Satellite data (CBERS) to detect and calculate the distribution, direction, wavelength and amplitude of internal waves in this area. The results show that the direction of these internal waves is offshore and their wavelength is about 150-200 m. The internal waves can be postulated as formed by upwelling or reversed tide.
