目的验证TIDE(Track of Indels by Decomposition)和TIDER(Tracking of Insertion,DEletions and Recombination events)分析绵羊囊胚基因组编辑结果的可靠性,为检测基因组编辑绵羊胚胎突变效率提供精准、及时的分析方法。方法TIDE是1...目的验证TIDE(Track of Indels by Decomposition)和TIDER(Tracking of Insertion,DEletions and Recombination events)分析绵羊囊胚基因组编辑结果的可靠性,为检测基因组编辑绵羊胚胎突变效率提供精准、及时的分析方法。方法TIDE是1种简便精准的检测方法,能精确测定CRISPR/Cas9在细胞群体中引发的靶向突变谱型和频率。利用TIDE平台对绵羊囊胚的基因组诱导突变进行表征分析与量化。结果以MSTN基因突变绵羊的基因组样本为材料,进行PCR扩增并构建T载体,随机选取单克隆测序。测序结果证实了TIDE分析基因组编辑结果的准确性。通过将TIDER分析单链寡核苷酸模板整合产生的编辑结果与DNA限制性酶切图谱对比,验证了TIDER分析外源DNA短片段导入的准确性。结论TIDE和TIDER工具可有效量化绵羊囊胚突变率,识别主要的插入和缺失类型,是高效经济的基因突变分析方法。展开更多
Accurate knowledge of mesospheric winds and waves is essential for studying the dynamics and climate in the mesosphere and lower thermosphere(MLT)region.In this study,we conduct a comparative analysis of the mesospher...Accurate knowledge of mesospheric winds and waves is essential for studying the dynamics and climate in the mesosphere and lower thermosphere(MLT)region.In this study,we conduct a comparative analysis of the mesosphere tidal results obtained from two adjacent meteor radars at low latitudes in Kunming,China,from November 2013 to December 2014.These two radars operate at different frequencies of 37.5 MHz and 53.1 MHz,respectively.However,overall good agreement is observed between the two radars in terms of horizontal winds and tide observations.The results show that the dominant tidal waves of the zonal and meridional winds are diurnal and semidiurnal tides.Moreover,we conduct an exhaustive statistical analysis to compare the tidal amplitudes and vertical wavelengths recorded by the dual radar systems,which reveals a high degree of alignment in tidal dynamics.The investigation includes variances and covariances of tidal amplitudes,which demonstrate remarkable consistency across measurements from both radars.This finding highlights clear uniformity in the mesospheric tidal patterns observed at low latitudes by the two neighboring meteor radars.Results of the comparative analysis specifically underscore the significant correlation in vertical wavelength measurements,validating the robustness of radar observations for tidal research.展开更多
The large-scale green tide(YSGT)has been persisting in the Yellow Sea over a decade,while its impacts on various trophic organisms remained inconclusive.Field surveys were conducted to investigate the dynamic of plank...The large-scale green tide(YSGT)has been persisting in the Yellow Sea over a decade,while its impacts on various trophic organisms remained inconclusive.Field surveys were conducted to investigate the dynamic of planktonic crustacean community in response to the massive blooming of Ulva biomass in the Subei Shoal and the adjacent water.A rapid change of the planktonic crustacean populations during the development process of YSGT was revealed by this study.Copepods,mysids and euphausiids,and amphipods were three major groups of the planktonic crustacean community in the survey region.Copepods were the dominant group,accounting for 82.16%±3.41%of the total biomass.The total biomass of planktonic crustaceans decreased from 70.98 mg/m3to 7.36 mg/m3with the bloom of Ulva algae.Copepods,mysids and euphausiids were the two groups contributing for the rapid decline.At the same time,amphipods showed evident species succession.The planktonic Themisto gaudichaudii absolutely dominated before the green tide,while the epizootic Sunamphitoe tea and Apohyale sp.succeeded during the bloom.Based on this study,the massive YSGTs seriously destructed the planktonic crustacean community and reduced the secondary productivity,which likely impaired the fishery resources and benthos through trophic chains.展开更多
We use a high-resolution numerical simulation to analyze the generation and evolution of semidiurnal internal tides in the Weddell-Scotia Confluence.Our results indicate that two ridges near the Antarctic Peninsula,th...We use a high-resolution numerical simulation to analyze the generation and evolution of semidiurnal internal tides in the Weddell-Scotia Confluence.Our results indicate that two ridges near the Antarctic Peninsula,the South Scotia Ridge(SSR)and the Philip Ridge(PR),are energetic sources of semidiurnal internal tides.The strongest semidiurnal barotropic to baroclinic energy conversion occurs around the crest of the SSR,reaching 0.3 W/m^(2).The depthintegrated,tidally averaged semidiurnal internal tide energy fluxes that radiated from the SSR reach about 2 kW/m.The northward semidiurnal internal tide energy fluxes entering the Scotia Sea are stronger than the southward energy fluxes entering the Powell Basin.For the SSR region between the South Orkney Plateau and Elephant Island,the areaintegrated barotropic to baroclinic conversion rate is 0.71 GW,of which 0.56 GW(79%)dissipates locally.The dissipation of internal tides occurs mainly in water depths of less than 1000 m.The dissipation rate over the SSR is as high as 10−7 W/kg.The energy fluxes create an anticlockwise gyre between the SSR and PR.The horizontal kinetic energy and available potential energy oscillate sinusoidally with peaks occurring at quarter-wavelength intervals.This energy pattern suggests the formation of standing waves due to interference between the semidiurnal internal tides originating from the SSR and PR.The results of this study show that internal tides and related mixing need to be considered in the analysis of water mass transformation in the Southern Ocean.展开更多
Red tide is an ecological disaster caused by the excessive proliferation of photosynthetic algae in the ocean.The frequent occurrences of red tide have brought serious harms to the marine aquaculture and caused signif...Red tide is an ecological disaster caused by the excessive proliferation of photosynthetic algae in the ocean.The frequent occurrences of red tide have brought serious harms to the marine aquaculture and caused significant economic losses to the marine industry.Red tide prediction can alleviate and even stop the long-term damages to marine ecosystems,which helps maintain the ecological balance of the ocean environment and contributes to the Sustainable Development Goal of“life below water”formulated by the United Nations.Aiming at red tide prediction using remote sensing technology,this study proposed a novel approach of red tide prediction using time-series hyperspectral observations,and examined the proposed method in the Xinghai Bay,China.Three spectral indices,namely the twoband ratio(TBR),the three-band spectral index(TBSI),and the fluorescence baseline height(FLH),were used to reduce the dimensionality of hyperspectral data and extract spectral features.Two machine learning models including the random forest(RF)and the support vector machine(SVM)were employed to predict whether red tide would occur on a target day based on the time-series spectral indices obtained in the previous days.By comparing and analyzing the prediction results of multiple machine learning models trained with different spectral indices and temporal lengths,it is found that both the RF and the SVM models can predict the red tide outbreaks at the accuracies over 0.9 using adequate temporal lengths of input data.When the temporal length of input data is limited,however,it is suggested to use the RF model,which accurately predicts red tide outbreaks using the temporal input of the 2-d TBSI.The proposed method is expected to provide oceanic and maritime agencies with early warnings on red tide outbreaks and ensure the safety of the coastal environment in large spatial scales using optical remote sensing technology.展开更多
Ocean mixing is a consequence of essential dynamic processes such as internal tides and lee waves that occur near the seafloor topography.Internal tides and lee waves are generated by barotropic tidal currents and geo...Ocean mixing is a consequence of essential dynamic processes such as internal tides and lee waves that occur near the seafloor topography.Internal tides and lee waves are generated by barotropic tidal currents and geostrophic flows,respectively.Ocean current is composed of multiple flows;thus,internal tides and lee waves occur concurrently in the real ocean.In this paper,the Massachusetts Institute of Technology general circulation model(MITgcm)is used to conduct 2D numerical experiments.By varying background flow intensities,the energy and dissipation relationship between internal tides and lee waves are investigated.The results reveal that the internal tide beams become asymmetric due to the influence of Doppler shift.The lee wave structure gradually leads the wave field when the background flow velocity rises constantly.The presence of a background flow increases the energy portion of the high-mode wave by up to 15%-20%.Moreover,strong shear,owing to the background flow,considerably increases dissipation.When the background flow velocity is higher than the barotropic tidal current velocity,the isopycnal overturn triggered by the lee wave generates a dissipation of the same order of magnitude as the shear.展开更多
As a frequently occurred marine pollution phenomenon,red tides of water body due to eutrophication cause massive mortality of marine organisms and serious ecological problems.The early warning and prediction of red ti...As a frequently occurred marine pollution phenomenon,red tides of water body due to eutrophication cause massive mortality of marine organisms and serious ecological problems.The early warning and prediction of red tide outbreak can provide guidance to the coastal management,and is of great value to the aquaculture industry and marine environment protection.An approach for the risk assessment of red tide occurrence using spectral indices was made.The optimal spectral indices were explored from three candidates,namely two-band ratio(TBR)method,three-band spectral index(TBSI)method,and fluorescence baseline(FLB)method.The correlations between the spectral indices and the red tide occurrence were quantitatively evaluated through analysis of variance(ANOVA).The risk maps for the Beibu Gulf and the Bohai Bay in China were produced with the normalized spectral indices based on the multi-spectral observation from Sentinel-3 satellite.Results show that both TBR and TBSI values have significant correlations with the occurrences of red tide as the ANOVA results.TBSI illustrated correctly the risk of red tide occurrence in the risk maps and was the optimal spectral index offshore risk assessment of red tide.FLB method failed to recognize the high-risk regions and may not be the appropriate spectral index.The risk assessment method proposed in this study can provide early alarms on red tide occurrence and help timely the countermeasure against potential harms.展开更多
Ulva prolifera green tides are becoming aworldwide environmental problem,especially in the Yellow Sea,China.However,the effects of the occurrence of U.prolifera green tides on the community organization and stability ...Ulva prolifera green tides are becoming aworldwide environmental problem,especially in the Yellow Sea,China.However,the effects of the occurrence of U.prolifera green tides on the community organization and stability of surrounding microbiomes have still not been de-termined.Here,the prokaryotic microbial community network stability and assembly char-acteristics were systematically analyzed and compared between the green tide and non-green tide periods.U.prolifera blooms weaken the community complexity and robustness of surrounding microbiomes,increasing fragmentation and decreasing diversity.Bacteria and archaea exhibited distinct community distributions and assembly patterns under the influ-ence of green tides,and bacterial communities were more sensitive to outbreaks of green tides.The bacterial communities exhibited a greater niche breadth and a lower phyloge-netic distance during the occurrence of U.prolifera green tides compared to those during the non-green tide period while archaeal communities remained unchanged,suggesting that the bacterial communities underwent stronger homogeneous selection and more sensitive to green tide blooms than the archaeal communities.Piecewise structural equation model analysis revealed that the different responses of major prokaryotic microbial groups,such as Cyanobacteria,to environmental variables during green tides,were influenced by the variations in pH and nitrate during green tides and correlated with the salinity gradient during the non-green tide period.This study elucidates the response of the adaptability,associations,and stability of surrounding microbiomes to outbreaks of U.prolifera green tides.展开更多
Motivated by the wide applications of empirical global ocean tide models in Earth science,particularly in shallow waters and coastal regions,we proposed an updated global ocean tide model representing all major diurna...Motivated by the wide applications of empirical global ocean tide models in Earth science,particularly in shallow waters and coastal regions,we proposed an updated global ocean tide model representing all major diurnal and semidiurnal tidal constituents.We integrated the development technique of the Technical University of Denmark(DTU10)model and calculated the residual tides using the intermediary FES2012 model.We utilized all available Topex/Poseidon,Jason-1,Ocean Surface Topography Mission(OSTM)/Jason-2 primary and tandem missions to develop the new model.To reduce the discrepancies between the model and in situ measurements estimated S2 tide constituent,the ERA-Interim model was selected for dry tropospheric correction of altimetry data.The newly developed model with an improved spatial resolution from 1/8°×1/8°to 1/16°×1/16°was assessed and compared against contemporary global ocean tide models using in situ measurements in coastal regions,continental shelf waters,marginal seas,and deep waters.The results demonstrate improvements in shallow waters and coastal regions,particularly in representative coastal re-gions such as the Northwest European Shelf and East Asian Marginal Seas.Moreover,the model performs well in simulating S_(2) and K_(2) tides with root mean square differences of 0.355 and 0.234 cm,respectively,against in situ measurements in deep waters world-wide.Compared with that of DTU10,the root sum square of the new model for the eight main tidal constituents decrease by 8.4%to 0.997 cm.展开更多
A parameterized internal tide dissipation term and self-attraction and loading(SAL) tide term are introduced in a barotropic numerical model to investigate the dynamics of semidiurnal tidal constituents M_2 and S_2 in...A parameterized internal tide dissipation term and self-attraction and loading(SAL) tide term are introduced in a barotropic numerical model to investigate the dynamics of semidiurnal tidal constituents M_2 and S_2 in the Bohai Sea, Yellow Sea and East China Sea(BYECS). The optimal parameters for bottom friction and internal dissipation are obtained through a series of numerical computations. Numerical simulation shows that the tide-generating force contributes 1.2% of M_2 power for the entire BYECS and up to 2.8% for the East China Sea deep basin. SAL tide contributes 4.4% of M_2 power for the BYECS and up to 9.3% for the East China Sea deep basin. Bottom friction plays a major role in dissipating tidal energy in the shelf regions, and the internal tide eff ect is important in the deep water regions. Numerical experiments show that artifi cial removal of tide-generating force in the BYECS can cause a signifi cant dif ference(as much as 30 cm) in model output. Artifi cial removal of SAL tide in the BYECS can cause even greater diff erence, up to 40 cm. This indicates that SAL tide should be taken into account in numerical simulations, especially if the tide-generating force is considered.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
By using 11 global ocean tide models and tidal gauge data obtained in the East China Sea and South China Sea, the influence of the ocean loading on gravity field in China and its neighbor area is calculated in this pa...By using 11 global ocean tide models and tidal gauge data obtained in the East China Sea and South China Sea, the influence of the ocean loading on gravity field in China and its neighbor area is calculated in this paper. Furthermore, the differences between the results from original global models and modified models with local tides are discussed based on above calculation. The comparison shows that the differences at the position near the sea are so large that the local tides must be taken into account in the calculation. When the global ocean tide models of CSR4.0, FES02, GOT00, NAO99 and ORI96 are chosen, the local effect for M2 is less than 0.10 × 10-8 m·s-2 over the area far away from sea. And the local effect for O1 is less than 0.05 × 10-8 m·s-2 over that area when choosing AG95 or CSR3.0 models. This numerical result demonstrates that the choice of model is a complex problem because of the inconsistent accuracy of the models over the areas of East and South China Seas.展开更多
Many studies point out that weather conditions involving temperature, wind power, monsoon transform, air pressure, sea condition, tide, ocean current, salinity, eutrophic environment and so on are key factors causing ...Many studies point out that weather conditions involving temperature, wind power, monsoon transform, air pressure, sea condition, tide, ocean current, salinity, eutrophic environment and so on are key factors causing Red Tide. In the red tide high frequency areas of the South China Sea, the eutrophic environment of sea water has already existed, so the key elements such as meteorological and hydrological conditions play an importance role in the occurrence of red tide. The atmospheric circulation maintenance and variation decide whether meteorological phenomena, and hydrological key elements stabilize or change. Moreover, the red tide organisms＇ breeding from the initial stage to the blooming reproduction stage, until reaching the biological density of the red tide, generally takes 4 - 5 days. In the paper, the red tide examples are analyzed in the past 10 years, and the weather circulation situation and hydro-meteorological key elements of it are counted to find the previous circulation mode and bring out important factors inducing the blooming of red tide. The predicted result in 2003 according to this method was satisfactory.展开更多
The annual frequency of red tides from 1977 to 2012 and the monthly frequency of red tides from 2001 to 2012 in China seas were used to establish the time series of red tide annual frequency and monthly frequency, res...The annual frequency of red tides from 1977 to 2012 and the monthly frequency of red tides from 2001 to 2012 in China seas were used to establish the time series of red tide annual frequency and monthly frequency, respectively. The annual frequency fit well with time segments revealed by piecewise linear regression analysis. The seasonal maximum of monthly frequency was in May （-18.22）, and the stochastic volatility tended to increase gradually with time series, with peak values occurring from May to July. Holt exponential smoothing and Holt-winter exponential smoothing were used to predict red tide annual and monthly frequencies, which revealed that the annual frequency of red tides would rise slowly by one time from 2013 to 2020, and that red tides would mainly occur from May to July in 2013-2016 with a peak value of about 25 times in May.展开更多
In this study,to meet the need for accurate tidal prediction,the accuracy of global ocean tide models was assessed in the South China Sea(0°–26°N,99°–121°E).Seven tide models,namely,DTU10,EOT11 a...In this study,to meet the need for accurate tidal prediction,the accuracy of global ocean tide models was assessed in the South China Sea(0°–26°N,99°–121°E).Seven tide models,namely,DTU10,EOT11 a,FES2014,GOT4.8,HAMTIDE12,OSU12 and TPXO8,were considered.The accuracy of eight major tidal constituents(i.e.,Q1,O1,P1,K1,N2,M2,S2 and K2)were assessed for the shallow water and coastal areas based on the tidal constants derived from multi-mission satellite altimetry(TOPEX and Jason series)and tide gauge observations.The root mean square values of each constituent between satellite-derived tidal constants and tide models were found in the range of 0.72–1.90 cm in the deep ocean(depth>200 m)and 1.18–5.63 cm in shallow water area(depth<200 m).Large inter-model discrepancies were noted in the Strait of Malacca and the Taiwan Strait,which could be attributable to the complicated hydrodynamic systems and the paucity of high-quality satellite altimetry data.In coastal regions,an accuracy performance was investigated using tidal results from 37 tide gauge stations.The root sum square values were in the range of 9.35–19.11 cm,with the FES2014 model exhibiting slightly superior performance.展开更多
The numerical method of lines(MOLs)in coordination with the classical fourth-order Runge Kutta(RK(4,4))method is used to solve shallow water equations(SWEs)for foreseeing water levels owing to the nonlinear interactio...The numerical method of lines(MOLs)in coordination with the classical fourth-order Runge Kutta(RK(4,4))method is used to solve shallow water equations(SWEs)for foreseeing water levels owing to the nonlinear interaction of tide and surge accompanying with a storm along the coast of Bangladesh.The SWEs are developed by extending the body forces with tide generating forces(TGFs).Spatial variables of the SWEs along with the boundary conditions are approximated by means of finite difference technique on an Arakawa C-grid to attain a system of ordinary differential equations(ODEs)of initial valued in time,which are being solved with the aid of the RK(4,4)method.Nested grid technique is adopted to solve coastal complexities closely with least computational cost.A stable tidal solution in the region of our choice is produced by applying the tidal forcing with the major tidal constituent M2(lunar semi-diurnal)along the southern open-sea boundary of the outer scheme.Numerical experimentations are carried out to simulate water levels generated by the cyclonic storm AILA along the coast of Bangladesh.The model simulated results are found to be in a reasonable agreement with the limited available reported data and observations.展开更多
With the rapid development of modern Interferometric Synthetic Aperture Radar(InSAR)missions,SAR instruments with wider coverage can be used to monitor the ground surface deformation from regional to global scale.Howe...With the rapid development of modern Interferometric Synthetic Aperture Radar(InSAR)missions,SAR instruments with wider coverage can be used to monitor the ground surface deformation from regional to global scale.However,the ocean tide loading(OTL)displacement is becoming a primary source of errors.It contributes to a long-wavelength signal in InSAR interferograms,leading to errors from millimeter to centimeter-level in InSAR deformation monitoring,especially over coastal areas.Although the state-of-the-art has applied ocean tide models to mitigate the errors,the difference between them and their impact on InSAR measurements are rarely discussed.In this paper,we compare representative ocean tide models and investigate their effects in the correction of OTL errors.We found that(i)the modeled OTL displacements from different models show little difference over interiors far from the ocean,while disagreement becomes larger over coastal areas;(ii)the magnitude of OTL artifacts may be greater than the atmospheric delays in some coastal areas,and the correction using ocean tide models can effectively attenuate the OTL effects for large-scale InSAR measurements;(iii)when correcting the OTL errors for InSAR measurements,the global model TPXO and FES are recommended because of their better overall performance,while the NAO model performs the worst.The local models with high spatial resolution can help improve the capability of coarse global models in complex topographic areas.展开更多
文摘目的验证TIDE(Track of Indels by Decomposition)和TIDER(Tracking of Insertion,DEletions and Recombination events)分析绵羊囊胚基因组编辑结果的可靠性,为检测基因组编辑绵羊胚胎突变效率提供精准、及时的分析方法。方法TIDE是1种简便精准的检测方法,能精确测定CRISPR/Cas9在细胞群体中引发的靶向突变谱型和频率。利用TIDE平台对绵羊囊胚的基因组诱导突变进行表征分析与量化。结果以MSTN基因突变绵羊的基因组样本为材料,进行PCR扩增并构建T载体,随机选取单克隆测序。测序结果证实了TIDE分析基因组编辑结果的准确性。通过将TIDER分析单链寡核苷酸模板整合产生的编辑结果与DNA限制性酶切图谱对比,验证了TIDER分析外源DNA短片段导入的准确性。结论TIDE和TIDER工具可有效量化绵羊囊胚突变率,识别主要的插入和缺失类型,是高效经济的基因突变分析方法。
基金supported by the National Natural Science Foundation of China (Grant Nos. 42125402 and 42174183)the National Key Technologies R&D Program of China (Grant No.2022YFF0503703)+2 种基金the B-type Strategic Priority Program of the Chinese Academy of Sciences (Grant No. XDB41000000)the foundation of the National Key Laboratory of Electromagnetic Environment and the Fundamental Research Funds for the Central Universitiesthe Chinese Meridian Project
文摘Accurate knowledge of mesospheric winds and waves is essential for studying the dynamics and climate in the mesosphere and lower thermosphere(MLT)region.In this study,we conduct a comparative analysis of the mesosphere tidal results obtained from two adjacent meteor radars at low latitudes in Kunming,China,from November 2013 to December 2014.These two radars operate at different frequencies of 37.5 MHz and 53.1 MHz,respectively.However,overall good agreement is observed between the two radars in terms of horizontal winds and tide observations.The results show that the dominant tidal waves of the zonal and meridional winds are diurnal and semidiurnal tides.Moreover,we conduct an exhaustive statistical analysis to compare the tidal amplitudes and vertical wavelengths recorded by the dual radar systems,which reveals a high degree of alignment in tidal dynamics.The investigation includes variances and covariances of tidal amplitudes,which demonstrate remarkable consistency across measurements from both radars.This finding highlights clear uniformity in the mesospheric tidal patterns observed at low latitudes by the two neighboring meteor radars.Results of the comparative analysis specifically underscore the significant correlation in vertical wavelength measurements,validating the robustness of radar observations for tidal research.
基金the National Natural Science Foundation of China(No.42276221)the Marine S&T Fund of Shandong Province for Laoshan Laboratory(No.LSK202203700)+1 种基金the National Key Research and Development Program of China(No.2022YFC3106000)the Taishan Scholars Program(No.tstp20230624)。
文摘The large-scale green tide(YSGT)has been persisting in the Yellow Sea over a decade,while its impacts on various trophic organisms remained inconclusive.Field surveys were conducted to investigate the dynamic of planktonic crustacean community in response to the massive blooming of Ulva biomass in the Subei Shoal and the adjacent water.A rapid change of the planktonic crustacean populations during the development process of YSGT was revealed by this study.Copepods,mysids and euphausiids,and amphipods were three major groups of the planktonic crustacean community in the survey region.Copepods were the dominant group,accounting for 82.16%±3.41%of the total biomass.The total biomass of planktonic crustaceans decreased from 70.98 mg/m3to 7.36 mg/m3with the bloom of Ulva algae.Copepods,mysids and euphausiids were the two groups contributing for the rapid decline.At the same time,amphipods showed evident species succession.The planktonic Themisto gaudichaudii absolutely dominated before the green tide,while the epizootic Sunamphitoe tea and Apohyale sp.succeeded during the bloom.Based on this study,the massive YSGTs seriously destructed the planktonic crustacean community and reduced the secondary productivity,which likely impaired the fishery resources and benthos through trophic chains.
基金The Doctor Foundation of Hebei Normal University of Science and Technology under contract No.2024YB039the Fundamental Research Funds for the Provincial Universities of Hebei under contract Nos 2023JK07 and 2022JK03+3 种基金the Major Science and Technology Support Project of Hebei Province under contract No.242S3301Zthe Fujian Provincial Natural Science Foundation of China under contract No.2021J05172the National Natural Science Foundation of China under contract No.42176244the CAS Key Deployment Project of Centre for Ocean Mega-Research of Science under contract No.COMS2020Q07.
文摘We use a high-resolution numerical simulation to analyze the generation and evolution of semidiurnal internal tides in the Weddell-Scotia Confluence.Our results indicate that two ridges near the Antarctic Peninsula,the South Scotia Ridge(SSR)and the Philip Ridge(PR),are energetic sources of semidiurnal internal tides.The strongest semidiurnal barotropic to baroclinic energy conversion occurs around the crest of the SSR,reaching 0.3 W/m^(2).The depthintegrated,tidally averaged semidiurnal internal tide energy fluxes that radiated from the SSR reach about 2 kW/m.The northward semidiurnal internal tide energy fluxes entering the Scotia Sea are stronger than the southward energy fluxes entering the Powell Basin.For the SSR region between the South Orkney Plateau and Elephant Island,the areaintegrated barotropic to baroclinic conversion rate is 0.71 GW,of which 0.56 GW(79%)dissipates locally.The dissipation of internal tides occurs mainly in water depths of less than 1000 m.The dissipation rate over the SSR is as high as 10−7 W/kg.The energy fluxes create an anticlockwise gyre between the SSR and PR.The horizontal kinetic energy and available potential energy oscillate sinusoidally with peaks occurring at quarter-wavelength intervals.This energy pattern suggests the formation of standing waves due to interference between the semidiurnal internal tides originating from the SSR and PR.The results of this study show that internal tides and related mixing need to be considered in the analysis of water mass transformation in the Southern Ocean.
基金The National Natural Science Foundation of China under contract No.42406188the Natural Science Foundation of Liaoning Province under contract No.2024-BS-022+1 种基金the Dalian High-Level Talent Innovation Program under contract No.2022RG02the Fundamental Research Funds for the Central Universities under contract No.3132025107.
文摘Red tide is an ecological disaster caused by the excessive proliferation of photosynthetic algae in the ocean.The frequent occurrences of red tide have brought serious harms to the marine aquaculture and caused significant economic losses to the marine industry.Red tide prediction can alleviate and even stop the long-term damages to marine ecosystems,which helps maintain the ecological balance of the ocean environment and contributes to the Sustainable Development Goal of“life below water”formulated by the United Nations.Aiming at red tide prediction using remote sensing technology,this study proposed a novel approach of red tide prediction using time-series hyperspectral observations,and examined the proposed method in the Xinghai Bay,China.Three spectral indices,namely the twoband ratio(TBR),the three-band spectral index(TBSI),and the fluorescence baseline height(FLH),were used to reduce the dimensionality of hyperspectral data and extract spectral features.Two machine learning models including the random forest(RF)and the support vector machine(SVM)were employed to predict whether red tide would occur on a target day based on the time-series spectral indices obtained in the previous days.By comparing and analyzing the prediction results of multiple machine learning models trained with different spectral indices and temporal lengths,it is found that both the RF and the SVM models can predict the red tide outbreaks at the accuracies over 0.9 using adequate temporal lengths of input data.When the temporal length of input data is limited,however,it is suggested to use the RF model,which accurately predicts red tide outbreaks using the temporal input of the 2-d TBSI.The proposed method is expected to provide oceanic and maritime agencies with early warnings on red tide outbreaks and ensure the safety of the coastal environment in large spatial scales using optical remote sensing technology.
基金supported by the National Natural Science Foundation of China(No.41876015)。
文摘Ocean mixing is a consequence of essential dynamic processes such as internal tides and lee waves that occur near the seafloor topography.Internal tides and lee waves are generated by barotropic tidal currents and geostrophic flows,respectively.Ocean current is composed of multiple flows;thus,internal tides and lee waves occur concurrently in the real ocean.In this paper,the Massachusetts Institute of Technology general circulation model(MITgcm)is used to conduct 2D numerical experiments.By varying background flow intensities,the energy and dissipation relationship between internal tides and lee waves are investigated.The results reveal that the internal tide beams become asymmetric due to the influence of Doppler shift.The lee wave structure gradually leads the wave field when the background flow velocity rises constantly.The presence of a background flow increases the energy portion of the high-mode wave by up to 15%-20%.Moreover,strong shear,owing to the background flow,considerably increases dissipation.When the background flow velocity is higher than the barotropic tidal current velocity,the isopycnal overturn triggered by the lee wave generates a dissipation of the same order of magnitude as the shear.
基金Supported by the National Key R&D Program of China(No.2023YFC3108300)the Dalian High-level Talent Innovation Program(No.2022RG02)the Fundamental Research Funds for the Central Universities(No.3132023507)。
文摘As a frequently occurred marine pollution phenomenon,red tides of water body due to eutrophication cause massive mortality of marine organisms and serious ecological problems.The early warning and prediction of red tide outbreak can provide guidance to the coastal management,and is of great value to the aquaculture industry and marine environment protection.An approach for the risk assessment of red tide occurrence using spectral indices was made.The optimal spectral indices were explored from three candidates,namely two-band ratio(TBR)method,three-band spectral index(TBSI)method,and fluorescence baseline(FLB)method.The correlations between the spectral indices and the red tide occurrence were quantitatively evaluated through analysis of variance(ANOVA).The risk maps for the Beibu Gulf and the Bohai Bay in China were produced with the normalized spectral indices based on the multi-spectral observation from Sentinel-3 satellite.Results show that both TBR and TBSI values have significant correlations with the occurrences of red tide as the ANOVA results.TBSI illustrated correctly the risk of red tide occurrence in the risk maps and was the optimal spectral index offshore risk assessment of red tide.FLB method failed to recognize the high-risk regions and may not be the appropriate spectral index.The risk assessment method proposed in this study can provide early alarms on red tide occurrence and help timely the countermeasure against potential harms.
基金supported by the National Key Research and Development Program of China(No.2022YFC2807500)Laoshan Laboratory(No.LSKJ202203201)+1 种基金the National Natural Science Foundation of China(Nos.42206147,42120104006 and 42176111)the Natural Science Foundation of Shandong Province(Nos.ZR2022QD046,ZR2021QD051).
文摘Ulva prolifera green tides are becoming aworldwide environmental problem,especially in the Yellow Sea,China.However,the effects of the occurrence of U.prolifera green tides on the community organization and stability of surrounding microbiomes have still not been de-termined.Here,the prokaryotic microbial community network stability and assembly char-acteristics were systematically analyzed and compared between the green tide and non-green tide periods.U.prolifera blooms weaken the community complexity and robustness of surrounding microbiomes,increasing fragmentation and decreasing diversity.Bacteria and archaea exhibited distinct community distributions and assembly patterns under the influ-ence of green tides,and bacterial communities were more sensitive to outbreaks of green tides.The bacterial communities exhibited a greater niche breadth and a lower phyloge-netic distance during the occurrence of U.prolifera green tides compared to those during the non-green tide period while archaeal communities remained unchanged,suggesting that the bacterial communities underwent stronger homogeneous selection and more sensitive to green tide blooms than the archaeal communities.Piecewise structural equation model analysis revealed that the different responses of major prokaryotic microbial groups,such as Cyanobacteria,to environmental variables during green tides,were influenced by the variations in pH and nitrate during green tides and correlated with the salinity gradient during the non-green tide period.This study elucidates the response of the adaptability,associations,and stability of surrounding microbiomes to outbreaks of U.prolifera green tides.
基金supported by the open funding of the Technology Innovation Center for South China Sea Re-mote Sensing,Surveying and Mapping Collaborative Ap-plication,Ministry of Natural Resources,P.R.China(No.RSSMCA-2024-B001)the National Natural Science Foundation of China(Nos.T2261149752 and 42476172).
文摘Motivated by the wide applications of empirical global ocean tide models in Earth science,particularly in shallow waters and coastal regions,we proposed an updated global ocean tide model representing all major diurnal and semidiurnal tidal constituents.We integrated the development technique of the Technical University of Denmark(DTU10)model and calculated the residual tides using the intermediary FES2012 model.We utilized all available Topex/Poseidon,Jason-1,Ocean Surface Topography Mission(OSTM)/Jason-2 primary and tandem missions to develop the new model.To reduce the discrepancies between the model and in situ measurements estimated S2 tide constituent,the ERA-Interim model was selected for dry tropospheric correction of altimetry data.The newly developed model with an improved spatial resolution from 1/8°×1/8°to 1/16°×1/16°was assessed and compared against contemporary global ocean tide models using in situ measurements in coastal regions,continental shelf waters,marginal seas,and deep waters.The results demonstrate improvements in shallow waters and coastal regions,particularly in representative coastal re-gions such as the Northwest European Shelf and East Asian Marginal Seas.Moreover,the model performs well in simulating S_(2) and K_(2) tides with root mean square differences of 0.355 and 0.234 cm,respectively,against in situ measurements in deep waters world-wide.Compared with that of DTU10,the root sum square of the new model for the eight main tidal constituents decrease by 8.4%to 0.997 cm.
基金Supported by the National Natural Science Foundation of China(Nos.40676009,40606006)the Qingdao Science and Technology Basic Research Program(No.11-1-4-98-jch)
文摘A parameterized internal tide dissipation term and self-attraction and loading(SAL) tide term are introduced in a barotropic numerical model to investigate the dynamics of semidiurnal tidal constituents M_2 and S_2 in the Bohai Sea, Yellow Sea and East China Sea(BYECS). The optimal parameters for bottom friction and internal dissipation are obtained through a series of numerical computations. Numerical simulation shows that the tide-generating force contributes 1.2% of M_2 power for the entire BYECS and up to 2.8% for the East China Sea deep basin. SAL tide contributes 4.4% of M_2 power for the BYECS and up to 9.3% for the East China Sea deep basin. Bottom friction plays a major role in dissipating tidal energy in the shelf regions, and the internal tide eff ect is important in the deep water regions. Numerical experiments show that artifi cial removal of tide-generating force in the BYECS can cause a signifi cant dif ference(as much as 30 cm) in model output. Artifi cial removal of SAL tide in the BYECS can cause even greater diff erence, up to 40 cm. This indicates that SAL tide should be taken into account in numerical simulations, especially if the tide-generating force is considered.
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.
基金The Key Knowledge Innovation Project (KZCX3-SW-131), the Hundred Talents Program of Chinese Academy of Sciences and the National Natural Science Foundation of China (40374029)
文摘By using 11 global ocean tide models and tidal gauge data obtained in the East China Sea and South China Sea, the influence of the ocean loading on gravity field in China and its neighbor area is calculated in this paper. Furthermore, the differences between the results from original global models and modified models with local tides are discussed based on above calculation. The comparison shows that the differences at the position near the sea are so large that the local tides must be taken into account in the calculation. When the global ocean tide models of CSR4.0, FES02, GOT00, NAO99 and ORI96 are chosen, the local effect for M2 is less than 0.10 × 10-8 m·s-2 over the area far away from sea. And the local effect for O1 is less than 0.05 × 10-8 m·s-2 over that area when choosing AG95 or CSR3.0 models. This numerical result demonstrates that the choice of model is a complex problem because of the inconsistent accuracy of the models over the areas of East and South China Seas.
文摘Many studies point out that weather conditions involving temperature, wind power, monsoon transform, air pressure, sea condition, tide, ocean current, salinity, eutrophic environment and so on are key factors causing Red Tide. In the red tide high frequency areas of the South China Sea, the eutrophic environment of sea water has already existed, so the key elements such as meteorological and hydrological conditions play an importance role in the occurrence of red tide. The atmospheric circulation maintenance and variation decide whether meteorological phenomena, and hydrological key elements stabilize or change. Moreover, the red tide organisms＇ breeding from the initial stage to the blooming reproduction stage, until reaching the biological density of the red tide, generally takes 4 - 5 days. In the paper, the red tide examples are analyzed in the past 10 years, and the weather circulation situation and hydro-meteorological key elements of it are counted to find the previous circulation mode and bring out important factors inducing the blooming of red tide. The predicted result in 2003 according to this method was satisfactory.
基金financially supported by the Tianjin Marine Science and Technology Project (KJXH2011-05)local colleges and universities in Shanghai liberal arts academic programme (B5201120003)
文摘The annual frequency of red tides from 1977 to 2012 and the monthly frequency of red tides from 2001 to 2012 in China seas were used to establish the time series of red tide annual frequency and monthly frequency, respectively. The annual frequency fit well with time segments revealed by piecewise linear regression analysis. The seasonal maximum of monthly frequency was in May （-18.22）, and the stochastic volatility tended to increase gradually with time series, with peak values occurring from May to July. Holt exponential smoothing and Holt-winter exponential smoothing were used to predict red tide annual and monthly frequencies, which revealed that the annual frequency of red tides would rise slowly by one time from 2013 to 2020, and that red tides would mainly occur from May to July in 2013-2016 with a peak value of about 25 times in May.
基金The National Key Research and Development Program of China under contract Nos 2017YFC0306003 and 2016YFB0501703the National Natural Science Foundation of China under contract Nos 41876111,41706115 and 41806214
文摘In this study,to meet the need for accurate tidal prediction,the accuracy of global ocean tide models was assessed in the South China Sea(0°–26°N,99°–121°E).Seven tide models,namely,DTU10,EOT11 a,FES2014,GOT4.8,HAMTIDE12,OSU12 and TPXO8,were considered.The accuracy of eight major tidal constituents(i.e.,Q1,O1,P1,K1,N2,M2,S2 and K2)were assessed for the shallow water and coastal areas based on the tidal constants derived from multi-mission satellite altimetry(TOPEX and Jason series)and tide gauge observations.The root mean square values of each constituent between satellite-derived tidal constants and tide models were found in the range of 0.72–1.90 cm in the deep ocean(depth>200 m)and 1.18–5.63 cm in shallow water area(depth<200 m).Large inter-model discrepancies were noted in the Strait of Malacca and the Taiwan Strait,which could be attributable to the complicated hydrodynamic systems and the paucity of high-quality satellite altimetry data.In coastal regions,an accuracy performance was investigated using tidal results from 37 tide gauge stations.The root sum square values were in the range of 9.35–19.11 cm,with the FES2014 model exhibiting slightly superior performance.
文摘The numerical method of lines(MOLs)in coordination with the classical fourth-order Runge Kutta(RK(4,4))method is used to solve shallow water equations(SWEs)for foreseeing water levels owing to the nonlinear interaction of tide and surge accompanying with a storm along the coast of Bangladesh.The SWEs are developed by extending the body forces with tide generating forces(TGFs).Spatial variables of the SWEs along with the boundary conditions are approximated by means of finite difference technique on an Arakawa C-grid to attain a system of ordinary differential equations(ODEs)of initial valued in time,which are being solved with the aid of the RK(4,4)method.Nested grid technique is adopted to solve coastal complexities closely with least computational cost.A stable tidal solution in the region of our choice is produced by applying the tidal forcing with the major tidal constituent M2(lunar semi-diurnal)along the southern open-sea boundary of the outer scheme.Numerical experimentations are carried out to simulate water levels generated by the cyclonic storm AILA along the coast of Bangladesh.The model simulated results are found to be in a reasonable agreement with the limited available reported data and observations.
基金This work was supported by the Natural Science Foundation of China(grant Nos.42074008,41804005,42174018).
文摘With the rapid development of modern Interferometric Synthetic Aperture Radar(InSAR)missions,SAR instruments with wider coverage can be used to monitor the ground surface deformation from regional to global scale.However,the ocean tide loading(OTL)displacement is becoming a primary source of errors.It contributes to a long-wavelength signal in InSAR interferograms,leading to errors from millimeter to centimeter-level in InSAR deformation monitoring,especially over coastal areas.Although the state-of-the-art has applied ocean tide models to mitigate the errors,the difference between them and their impact on InSAR measurements are rarely discussed.In this paper,we compare representative ocean tide models and investigate their effects in the correction of OTL errors.We found that(i)the modeled OTL displacements from different models show little difference over interiors far from the ocean,while disagreement becomes larger over coastal areas;(ii)the magnitude of OTL artifacts may be greater than the atmospheric delays in some coastal areas,and the correction using ocean tide models can effectively attenuate the OTL effects for large-scale InSAR measurements;(iii)when correcting the OTL errors for InSAR measurements,the global model TPXO and FES are recommended because of their better overall performance,while the NAO model performs the worst.The local models with high spatial resolution can help improve the capability of coarse global models in complex topographic areas.
