Cirrus clouds play a crucial role in the energy balance of the Earth-atmosphere system.We investigated the spatiotemporal variations of cirrus over the South China Sea(SCS)using satellite data(MOD08,MYD08,CALIPSO)and ...Cirrus clouds play a crucial role in the energy balance of the Earth-atmosphere system.We investigated the spatiotemporal variations of cirrus over the South China Sea(SCS)using satellite data(MOD08,MYD08,CALIPSO)and reanalysis data(MERRA-2)from March 2007 to February 2015(eight years).The horizontal distribution reveals lower cirrus fraction values in the northern SCS and higher values in the southern region,with minima observed in March and April and maxima sequentially occurring in August(northern SCS,NSCS),September(middle SCS,MSCS),and December(southern SCS,SSCS).Vertically,the cirrus fraction peaks in summer and reaches its lowest levels in spring.Opaque cirrus dominates during summer in the NSCS and MSCS,comprising 53.6%and 55.9%,respectively,while the SSCS exhibits a higher frequency of opaque cirrus relative to other cloud types.Subvisible cirrus clouds have the lowest frequency year-round,whereas thin cirrus is most prominent in winter in the NSCS(46.3%)and in spring in the MSCS(45.3%).A case study from September 2021 further explores the influence of ice crystal habits on brightness temperature(BT)over the SCS.Simulations utilizing five ice crystal shapes from the ARTS DDA(Atmospheric Radiative Transfer Simulator Discrete Dipole Approximation)database and the RTTOV 12.4 radiative transfer model reveal that the 8-column-aggregate shape best represents BT in the NSCS and SSCS,while the large-block-aggregate shape performs better in the SSCS.展开更多
The prediction of sea surface partial pressure of carbon dioxide(pCO_(2))in the South China Sea is crucial for understanding the region’s contribution to the global carbon budget and its interactions with climate cha...The prediction of sea surface partial pressure of carbon dioxide(pCO_(2))in the South China Sea is crucial for understanding the region’s contribution to the global carbon budget and its interactions with climate change.We applied the Spatiotemporal Convolutional Long Short-Term Memory(STConvLSTM)model,integrating key environmental factors including sea surface temperature(SST),sea surface salinity(SSS),and chlorophyll a(Chl a),to predict and analyze sea surface pCO_(2)in the South China Sea.The model demonstrated high accuracy in short-term predictions(1 month),with a mean absolute error(MAE)of 0.394,a root mean square error(RMSE)of 0.659,and a coefficient of determination(R^(2))of 0.998.For long-term predictions(12 months),the model maintained its predictive capability,with an MAE of 0.667,RMSE of 1.255,and R^(2)of 0.994.Feature importance analysis revealed that sea surface pCO_(2)and SST were the main drivers of the model’s predictions,whereas Chl a and SSS had relatively minor impacts.The model’s generalization ability was further validated in the northwest Pacific Ocean and tropical Pacific Ocean,where it successfully captured the spatiotemporal variation in pCO_(2)with small prediction errors.The ST-ConvLSTM model provides an efficient and accurate tool for forecasting and analyzing sea surface pCO_(2)in the South China Sea,offering new insights into global carbon cycling and climate change.This study demonstrates the potential of deep learning in marine science and provides a significant technical support for global changes and marine ecosystem research.展开更多
The Fushan Depression is one of the petroliferous depressions in the Beibuwan Basin,South China Sea.Previous studies have preliminarily explored the origin and source of crude oils in some areas of this depression.Nev...The Fushan Depression is one of the petroliferous depressions in the Beibuwan Basin,South China Sea.Previous studies have preliminarily explored the origin and source of crude oils in some areas of this depression.Nevertheless,no systematic investigations on the classification and origin of oils and hy-drocarbon migration processes have been made for the entire petroleum system in this depression,which has significantly hindered the hydrocarbon exploration in the region.A total of 32 mudstone and 58 oil samples from the Fushan Depression were analyzed to definite the detailed oil-source correlation within the sequence and sedimentary framework.The organic matter of third member of Paleogene Liushagang Formation(Els(3))source rocks,both deltaic and lacustrine mudstone,are algal-dominated with high abundance of C_(23)tricyclic terpane and C_(30)4-methylsteranes.The deltaic source rocks occur-ring in the first member(Els_(1))and second member(Els_(2))of the Paleogene Liushagang Formation are characterized by high abundance of C_(19+20)tricyclic terpane and oleanane,reflecting a more terrestrial plants contribution.While lacustrine source rocks of Els_(1)and Els_(2)display the reduced input of terrige-nous organic matter with relatively low abundance of C 19+20 tricyclic terpane and oleanane.Three types of oils were identified by their biomarker compositions in this study.Most of the oils discovered in the Huachang and Bailian Els_(1)reservoir belong to group A and were derived from lacustrine source rocks of Els_(1)and Els_(2).Group B oils are found within the Els_(1)and Els_(2)reservoirs,showing a close relation to the deltaic source rocks of Els_(1)and Els_(2),respectively.Group C oils,occurring in the Els3 reservoirs,have a good affinity with the Els3 source rocks.The spatial distribution and accumulation of different groups of oils are mainly controlled by the sedimentary facies and specific structural conditions.The Els_(2)reservoir in the Yong'an area belonging to Group B oil,are adjacent to the source kitchen and could be considered as the favorable exploration area in the future.展开更多
Southerly moisture surges over the central South China Sea(SCS)are characterized by the strengthening of lowlevel southerlies that transport moisture northward from the Pacific or Indian Oceans to South China.These su...Southerly moisture surges over the central South China Sea(SCS)are characterized by the strengthening of lowlevel southerlies that transport moisture northward from the Pacific or Indian Oceans to South China.These surge events typically occur for days in the early-summer season(from April to June)and can lead to heavy rains in South China.This study categorizes surge events into three types of flow patterns and examines their multiscale variations and impacts on rainfall.The first type occurs mainly in April,with the southeasterlies enhanced by a deepening trough in South China and the western Pacific subtropical high established over the SCS.The second type of surge events mostly appears in June,featuring the prevailing southwesterlies of summer monsoon from the Indian Ocean during the active phases of intraseasonal oscillations.Most surge events exhibit semi-diurnal variations with morning and afternoon peaks of northward moisture fluxes.Specifically,the first type features a dominant afternoon peak,while the second type shows a dominant early-morning peak,which is induced by thermal contrast between the Indochina Peninsula and the SCS.In general,the surge events enhance moisture convergence and increase rainfall downstream in South China,but they show some regional differences.The second type strengthens moisture convergence and rainfall in coastal regions with a morning peak.In contrast,the first type enhances inland rainfall with a morning peak,while moisture divergence dominates coastal regions.The third type of surge events denotes transitional conditions between the first two types,in terms of atmospheric circulations,diurnal cycles,and rainfall patterns.These results highlight a diversity of regional moisture surges and related rainfall ranging from diurnal to sub-seasonal scales.展开更多
Steel catenary riser represents the pioneering riser technology implemented in China’s deep-sea oil and gas opera-tions.Given the complex mechanical conditions of the riser,extensive research has been conducted on it...Steel catenary riser represents the pioneering riser technology implemented in China’s deep-sea oil and gas opera-tions.Given the complex mechanical conditions of the riser,extensive research has been conducted on its dynamic analysis and structural design.This study investigates a deep-sea oil and gas field by developing a coupled model of a semi-submersible platform and steel catenary riser to analyze it mechanical behavior under extreme marine condi-tions.Through multi-objective optimization methodology,the study compares and analyzes suspension point tension and touchdown point stress under various conditions by modifying the suspension position,suspension angle,and catenary length.The optimal configuration parameters were determined:a suspension angle of 12°,suspension position in the southwest direction of the column,and a catenary length of approximately 2000 m.These findings elucidate the impact of configuration parameters on riser dynamic response and establish reasonable parameter layout ranges for adverse sea conditions,offering valuable optimization strategies for steel catenary riser deployment in domestic deep-sea oil and gas fields.展开更多
Based on petroleum exploration and new progress of oil and gas geology study in the Qiongdongnan Basin,combined with seismic,logging,drilling,core,sidewall coring,geochemistry data,a systematic study is conducted on t...Based on petroleum exploration and new progress of oil and gas geology study in the Qiongdongnan Basin,combined with seismic,logging,drilling,core,sidewall coring,geochemistry data,a systematic study is conducted on the source,reservoir-cap conditions,trap types,migration and accumulation characteristics,enrichment mechanisms,and reservoir formation models of ultra-deep water and ultra-shallow natural gas,taking the Lingshui 36-1 gas field as an example.(1)The genetic types of the ultra-deep water and ultra-shallow natural gas in the Qiongdongnan Basin include thermogenic gas and biogenic gas,and dominated by thermogenic gas.(2)The reservoirs are mainly composed of the Quaternary deep-water submarine fan sandstone.(3)The types of cap rocks include deep-sea mudstone,mass transport deposits mudstone,and hydrate-bearing formations.(4)The types of traps are mainly lithological,and also include structural-lithological traps.(5)The migration channels include vertical transport channels such as faults,gas chimneys,fracture zones,and lateral transport layers such as large sand bodies and unconformity surfaces,forming a single or composite transport framework.A new natural gas accumulation model is proposed for ultra-deep water and ultra-shallow layers,that is,dual source hydrocarbon supply,gas chimney and submarine fan composite migration,deep-sea mudstone-mass transport deposits mudstone-hydrate-bearing strata ternary sealing,late dynamic accumulation,and large-scale enrichment at ridges.The new understanding obtained from the research has reference and enlightening significance for the next step of deepwater and ultra-shallow layers,as well as oil and gas exploration in related fields or regions.展开更多
The environmental impact of microplastic pollution has triggered the alarm of public for over 20 years.The South China Sea,situated as a marginal sea in the tropical region,is surrounded by unique blue-carbon ecosyste...The environmental impact of microplastic pollution has triggered the alarm of public for over 20 years.The South China Sea,situated as a marginal sea in the tropical region,is surrounded by unique blue-carbon ecosystems and densely populated provinces that produce a substantial amount of industrial plastic waste.Understanding the source-sink relationship and distribution of microplastics in rivers,nearshores,and estuaries is crucial for safeguarding the ecological integrity of estuarine environments.In this review,a comprehensive review of recent researches on the distribution and source-sink relationships of microplastics in rivers and nearshore and offshore regions in the South China Sea have been discussed.Due to atmospheric deposition and precipitation,microplastics exhibit spatial heterogeneity in terms of abundance and distribution in areas surrounding the South China Sea.The major pollution sources include river inputs,industrial wastewater discharge,aquaculture activities,and shipping operations.Anthropogenic and other biological factors such as fish ingestion and vegetation entrapment also affect the distribution and transport of microplastics.To quantify the abundance and distribution of microplastics and elucidate their transport mechanisms,it is recommended to strengthen the detection and management of microplastics in the South China Sea region,standardize sampling methods and units,establish shared databases,and explore effective governance pathways.展开更多
High-accuracy Sea level prediction is important for understanding marine environments and climate change.In this work,a deep convolutional neural network(CNN)combined with attention mechanism(ADNN)is established for s...High-accuracy Sea level prediction is important for understanding marine environments and climate change.In this work,a deep convolutional neural network(CNN)combined with attention mechanism(ADNN)is established for sea level anomaly(SLA)prediction from historical satellite observations.Multi-year(1998-2020)radar altimetry observed SLA pattern samples in the South China Sea are used for model training and testing.Compared with existing deep learning models such as CNN and convolutional long short-term memory(ConvLSTM)network,ADNN demonstrates the highest accuracies of 94.0%,91.1%,88.4%and 86.2%for 1-d,3-d,5-d and 7-d SLA field predictions,with regional average root mean square errors(RMSE)of 0.27 cm,0.51 cm,0.80 cm and 1.09 cm,respectively.The integration of CNN and attention mechanism significantly improves the model performance,especially in estimating short-term sea level changes,with a 74.7%reduction in the RMSE for 1-d predictions compared to the baseline CNN model.Comparative experiments also show that the ADNN model performs well when the input data contains a certain degree of noise.Moreover,a multivariate ADNN(M-ADNN)model is designed to investigate the impacts of environmental variables such as sea surface temperature(SST)and wind on SLA prediction.The model yields a slightly higher accuracy but the results are quite similar to those of the ADNN model.The findings suggest that,although SST or wind can affect sea level changes,the ADNN model demonstrates the ability to identify and learn sufficient information about sea level changes solely from satellite altimetry measurements of SLA,especially for relatively long-term(≥5 d)predictions.This eliminates the need for additional input parameter data,thereby improving the SLA prediction efficiency.展开更多
Studying the characteristics and mechanisms of convective and non-convective cirrus clouds over the South China Sea is vital for their impact on regional climate dynamics,and enhancing predictive models for weather an...Studying the characteristics and mechanisms of convective and non-convective cirrus clouds over the South China Sea is vital for their impact on regional climate dynamics,and enhancing predictive models for weather and climate forecasts.This study utilizes eight years of CALIPSO data(from March 2007 to February 2015)to investigate convective and non-convective cirrus clouds.Explicit new insights include the observation that convective cirrus cloud samples are three times more numerous than non-convective cirrus clouds.Convective cirrus clouds are associated with humid conditions and demonstrate higher ice water content(IWC)values ranging from 10^(−3)to 10^(−1)g m^(−3),whereas non-convective cirrus clouds tend to be drier,exhibiting IWC values ranging from 10^(−4)to 10^(−3)g m^(−3).Both cirrus cloud types exhibit a maximum cloud fraction at 10°N.Convective cirrus reach their peak cloud fraction at an altitude of 14 km,while non-convective cirrus typically occur at altitudes between 15 and 16 km.The seasonal variability of the convective cirrus cloud fraction primarily reflects bottom-up positive specific humidity anomalies originating from convective activity,whereas the non-convective cirrus cloud fraction is influenced by top-down negative temperature anomalies.展开更多
Extreme wind events in the South China Sea(SCS)directly threaten maritime safety.With climate change altering their patterns,frequency,and intensity,understanding these changes is increasingly important.This study sys...Extreme wind events in the South China Sea(SCS)directly threaten maritime safety.With climate change altering their patterns,frequency,and intensity,understanding these changes is increasingly important.This study systematically investigates their spatiotemporal characteristics using high-resolution ERA5 reanalysis data from 1940 to 2023.The climatological wind speed exhibits a bimodal structure,with northeast winds dominating in winter and southwest winds prevalent in summer.During 1940−2023,the annual mean wind speed shows a modest upward trend of 0.01±0.02 m/s per decade,with notable seasonal and spatial variation.These changes in mean-state wind conditions strongly influence extreme wind(EW95)events,defined as daily maximum wind gusts exceeding the local 95th percentile.The EW95 events occur about 16 d annually,with typical speeds reaching 18.8 m/s.The spatial distribution of EW95 frequency displays an inverse relationship with intensity which closely aligns with climatological wind patterns.Seasonally,frequency peaks in December,matching the climatological wind speed,while peak intensity occurs in October and resurges in April,indicating decoupled seasonal patterns between frequency and intensity.Over the study period,EW95 events have become both more frequent and intense.Frequency increased by(0.71±0.37)d/a per decade,while intensity rose by(0.06±0.05)m/s per decade outpacing mean wind speed changes.Seasonal trends reveal a growing concentration of EW95 events in winter,with intensified events in late spring and late summer,despite decreased frequencies during these periods.These findings highlight significant changes in extreme winds behavior in the SCS under climate change,offering valuable insights for risk management and adaptation strategies.展开更多
As one of the micro-blocks dispersed in the South China Sea(SCS),the Xisha Islands are covered by thick Cenozoic sedimentary layers,making it challenging to obtain magmatic rocks.Well CK-2 is a kilometer-scale scienti...As one of the micro-blocks dispersed in the South China Sea(SCS),the Xisha Islands are covered by thick Cenozoic sedimentary layers,making it challenging to obtain magmatic rocks.Well CK-2 is a kilometer-scale scientific drilling project on the Xisha Islands in the northwestern SCS.It penetrates the thick reef limestone and reaches basaltic pyroclastic rocks.This study presents the whole-rock and olivine compositions of the basaltic volcaniclastic rocks from Well CK-2.These rocks exhibited ocean island basalt signatures characterized by the enrichment of light rare earth elements and high-field-strength elements.Compared with partial melting products derived from mantle peridotite,whole-rock compositions showed elevated Fe/Mn and Zn/Fe mass ratios.Additionally,olivines were characterized by a lower Ca content,higher Ni content,elevated Fe/Mn mass ratios,and moderate Mn/Zn mass ratios compared to those crystallized from peridotitic melts.The compositions of both the whole-rock and olivine phenocrysts indicate the presence of pyroxenite in the mantle source,which likely formed through the reaction of recycled oceanic crust with the surrounding mantle peridotite.Using the olivine-liquid Mg-Fe exchange thermometer,this study derived mantle potential temperatures(T_(p))ranging from 1502℃to 1756℃,which is consistent with those of plume-related ocean island basalts.Furthermore,the basaltic volcaniclastic rocks exhibit low H_(2)O contents(0.01%–1.47%),which were significantly lower than those found in the primary magmas of Large Igneous Provinces.These results suggest that the basaltic volcaniclastic rocks on the Xisha Islands originated from a volatile-poor mantle plume source.展开更多
Magmatism at continental margins is of great significance in understanding the continental rifting.We present a twodimensional P-wave velocity model derived from an ocean bottom seismometer experiment,conducted across...Magmatism at continental margins is of great significance in understanding the continental rifting.We present a twodimensional P-wave velocity model derived from an ocean bottom seismometer experiment,conducted across the middle northern continental margin of the South China Sea(SCS).The detailed velocity structures reveal significant heterogeneities extending from the continental shelf to the continent-ocean transition zone.The crust exhibits its greatest thickness below the continental shelf,measuring~23 km and gradually thins to~13 km at the distal margin.Furthermore,a narrow and distinct continent-ocean transition with only 40-km width is revealed.We also observe a high-velocity layer within the transition zone,reaching thickness of up to 4 km,characterized by P-wave velocities ranging from 7.0 km/s to 7.6 km/s in the lower crust.Based on the syn-rift melt generation using decompression melting model,we ascertain that syn-rift magmatism cannot fully account for the observed thick high-velocity layer.By integrating findings from previous geophysical and geochemical studies presenting extensive volcanic edifice on the seafloor at the northern margin,as well as ocean-island-basalt-type magmaticsamples in the SCS area,we propose that post-rifting magmatism associated with the Hainan Plume may have influenced theformation of the high-velocity lower crust within the transition zone and the northern margin of the SCS can thus be recognizedas magma-poor type margin.展开更多
The South China Sea winter monsoon(SCSWM),an integral component of the East Asian winter monsoon,connects extratropical and tropical regions.Utilizing ERA5 reanalysis and PAMIP simulations,the relationship between Arc...The South China Sea winter monsoon(SCSWM),an integral component of the East Asian winter monsoon,connects extratropical and tropical regions.Utilizing ERA5 reanalysis and PAMIP simulations,the relationship between Arctic sea ice and the SCSWM is investigated.The authors reveal that its strongest relationship with Arctic sea ice occurs in the North Pacific sector,i.e.,the Sea of Okhotsk and western Bering Sea.This link persists throughout the cold season,peaks when sea ice precedes the SCSWM by one month,and is independent of ENSO.North Pacific sea-ice loss weakens the meridional temperature gradient(MTG)and vertical wind shear in midlatitudes,reducing baroclinic eddy formation.Given the reduced zonal wind according to the thermal wind relation,the reduced wave activity flux in the upper troposphere must be balanced by equatorward wind based on the quasi-geostrophic momentum equation.This generates an anomalous meridional overturning circulation with descent and low-level divergence around 30°N,which intensifies the divergent component of the SCSWM.The divergent northerly anomalies also lead to cold advection and subtropical cooling.The enhanced MTG due to the subtropical cooling and weakened MTG due to high-latitude warming closely tied to reduced North Pacific sea ice displace the westerly jet southward,creating cyclonic shears over the North Pacific and intensifying the rotational component of the SCSWM.These findings establish North Pacific sea ice as a non-ENSO driver of the SCSWM,holding substantial implications for the predictability of the SCSWM.展开更多
Analyzing coral reef topography is critical for understanding both the formation mechanisms of coral reefs and coral spatial distribution patterns.However,most topographic studies have focused on small-scale or locali...Analyzing coral reef topography is critical for understanding both the formation mechanisms of coral reefs and coral spatial distribution patterns.However,most topographic studies have focused on small-scale or localized survey sites,and investigations of reef macro-topography patterns and their relationship with coral distribution are scant.To address this gap,we conducted a comprehensive investigation of macro-topographic patterns across 12 coral reefs covering 607 km2 in the Xisha Islands,South China Sea.Using digital elevation models constructed from satellite bathymetric data with 16 m resolution,we analyzed spatial variations of seven topographic indices at the reef,geomorphic zone,and reef slope orientation levels in shallow waters.Field surveys were integrated with topographic indices to interpret and model coral distribution patterns.Our results revealed significant topographic heterogeneity,particularly in reef slopes and lagoon patch reefs.Reef slopes ranged from 0°to 33°,with rugosity values between 1.00 and 1.19.The steepness of reef slopes varied by orientation,being steepest in the west,southwest,and south,while the consistency of slope gradients was highest in the south,east,and northeast.Furthermore,stress-tolerant coral cover on reef slopes was effectively predicted by the factors of topographic indices,water depth,and slope aspect.Additionally,the topographic changes in reef flats and shallow lagoons were minimal.These findings advance our understanding of coral reef formation mechanisms in the Indo-Pacific region and provide a theoretical foundation for the conservation and restoration of coral reef ecosystems.展开更多
Based on year-long mooring observations(January-December 2013)near the Xisha Islands in the northwestern South China Sea,this study investigates the characteristics of typhoon-induced near-inertial waves(NIWs)during t...Based on year-long mooring observations(January-December 2013)near the Xisha Islands in the northwestern South China Sea,this study investigates the characteristics of typhoon-induced near-inertial waves(NIWs)during three events(typhoons Wutip,Nari,and Haiyan).The influence of mesoscale eddies on NIWs and the interaction between NIWs and internal tides(ITs)were analyzed.Notably,near-inertial kinetic energy(NIKE)increased significantly following typhoon Haiyan,reaching a peak value of 40.60 J/m^(3),the highest recorded NIKE in 2013.This value was approximately threefold and fivefold larger than those generated by typhoons Wutip and Nari,respectively.NIKE generated by all three typhoons exhibited downward radiation.Power spectral analysis revealed significant frequency shifts in NIWs during each typhoon,with shifts linked to mesoscale eddies present at the observation site.Additionally,bicoherence analysis reveals that the fD_(1)(f+D_(1))and D_(2)−f waves(where f is the local inertial frequency,and D1 and D_(2)denote the frequencies of diurnal and semidiurnal ITs,respectively)in the power spectrum originate from the nonlinear interactions between NIWs and ITs during typhoons Wutip and Haiyan.Temporal analysis of kinetic energy and shear showed that the enhancement of nonlinear coupling between NIWs and ITs was primarily driven by the strong NIWs with strong vertical shear.This study provides valuable insights into the generation,propagation,and interaction of NIWs and ITs,contributing to a deeper understanding of ocean mixing processes in response to different typhoon conditions.展开更多
The sea surface temperature(SST)front over the northern South China Sea(NSCS)has significant impacts on regional weather,climate,and marine ecology.Based on high-resolution satellite data and reanalysis data,the long-...The sea surface temperature(SST)front over the northern South China Sea(NSCS)has significant impacts on regional weather,climate,and marine ecology.Based on high-resolution satellite data and reanalysis data,the long-term variation characteristics and possible mechanisms of the SST front intensity(SSTFI)over the NSCS in winter from 1986 to 2020 are analyzed.The results show that:(1)Based on empirical orthogonal decomposition analysis,the evolution features of SST front mainly include two types:position shift type and an intensity variation type.(2)The SSTFI is accelerating in recent two decades.From 1986 to 2003(P1),the SSTFI changed relatively smoothly[0.2℃/(km·decade)],while from 2004 to 2020(P2),there is a significant strengthening trend[1.2℃/(km·decade)].(3)The horizontal advection related to the ocean current dominates the intensification of the SST front.An anomalous cyclonic circulation in upper ocean of the NSCS and the coastal current of South China strengthen the cold advection,resulting in cooling of the coastal waters of South China.(4)The latent heat flux dominates the sea surface heat loss and cooling process,but both latent and sensible heat flux are not conducive to the enhancement of the SSTFI.(5)The increase in SSTFI is largely associated with La Niña-like pattern,which is conducive to enhance the East Asia winter monsoon,and strengthens the ocean front through air-sea interactions.This study provides a scientific reference for understanding the variations of the SSTFI.展开更多
This study explores the impact of the tropical sea surface temperature(SST) independent of the preceding winter El Nino–Southern Oscillation(ENSO) events(ENSO-independent SST) on the interannual variability of the So...This study explores the impact of the tropical sea surface temperature(SST) independent of the preceding winter El Nino–Southern Oscillation(ENSO) events(ENSO-independent SST) on the interannual variability of the South China Sea Summer Monsoon(SCSSM) and the associated mechanisms. During summer, the ENSO-independent SST component dominates across tropical ocean regions. The tropical ENSO-independent SSTs during spring and summer in the Maritime Continent(MC), the equatorial central-eastern Pacific(CEP), and the tropical Atlantic Ocean(TAO) regions play a comparably significant role in the interannual variation of the SCSSM intensity, compared to the tropical SST dependent on the preceding winter ENSO. The ENSO-independent SST anomalies(SSTA) in the TAO during spring and summer exhibit significant persistence. They can influence the SCSSM through westward propagation of teleconnection, as well as through eastward-propagating Kelvin waves. In summer, the SSTA in the MC, CEP, and TAO regions contribute jointly to the variability of the SCSSM. The MC SSTA affects local convection and generates anomalous meridional circulation to impact the SCSSM intensity. The CEP SSTA directly influences the SCSSM via the Matsuno-Gill response mechanism and indirectly affects it via meridional circulation by modulating vertical motions over the MC through zonal circulation. The TAO SSTA impacts the SCSSM through both westward and eastward pathways, as well as by influencing zonal circulation patterns in the tropical and subtropical North Pacific. The results offer valuable insights into the factors influencing the interannual variability of the SCSSM intensity.展开更多
Using literature published from 2010 onwards, this study investigates the ~3 500 km extension of the shallow shelf current in the South China Sea(SCS) during the winter and summer monsoons. This current is later ackno...Using literature published from 2010 onwards, this study investigates the ~3 500 km extension of the shallow shelf current in the South China Sea(SCS) during the winter and summer monsoons. This current is later acknowledged as the South China Sea shallow shelf Current(SCSSC). This current is primarily driven by monsoonal winds, and influenced by regional river plumes [Zhujiang(Pearl) River, Hong River, Mekong River] and the prominent South China Sea Warm Current(SCSWC) and South China Sea Western Boundary Current(SCSWBC). The current exhibits significant seasonal variations in both direction and pattern. During winter, it flows along the northern South China Sea's(NSCS) shelf and splits into two branches at the east of Hainan Island. One branch enters the Beibu Gulf through the Qiongzhou Strait and forms a major cyclonic circulation within the gulf, while the other branch flows southwestward along the southern coast of Hainan Island. These branches converge around 16°N latitude at the east of the Vietnamese shelf, then flow southward along the Sunda Shelf, where they deflect southwestward in “broadband”forms before curving southeastward along the east coast of Peninsular Malaysia(ECPM) and exiting via the Karimata Strait. In summer, the current exhibits a complex pattern. At the Sunda Shelf, it flows northwestward along the ECPM,then deflects northeastward around 6°N latitude, forming the Sunda Shelf's anti-cyclonic eddy(SSE) and causing upwelling on the east coast of Peninsular Malaysia(ECPMU). Near the eastern Vietnamese shelf, the current splits around 11°-12°N latitude into three distinct currents: the southward-flowing Vietnam Current, the northward-flowing Vietnam Meandering Current(VMC), and the southward-flowing SCSWBC. The VMC flows northward and then deflects northeastward south of Hainan Island, continuing northeastward along the NSCS's shelf and exiting through the Taiwan Strait.展开更多
The Early Eocene Climate Optimum(EECO) represents the peak of the early Paleogene greenhouse climate.However,a comprehensive understanding of the terrestrial paleoenvironmental response to the EECO and its implication...The Early Eocene Climate Optimum(EECO) represents the peak of the early Paleogene greenhouse climate.However,a comprehensive understanding of the terrestrial paleoenvironmental response to the EECO and its implications for organic matter(OM) enrichment remains lacking.We integrated sedimentological,astrochronological,and geochemical data from South China Sea sediments to reconstruct the paleoenvironment and establish the OM enrichment model during the EECO.Astronomical time scales(ATS) for the Lower Wenchang Formation(Lower WC Fm.) in the Kaiping Sag,South China Sea,were established,spanning 55.4 to 43.9 Ma.During 51.5-48.7 Ma,records of astronomical signal(with overlapping cycles of 2.4 Ma,1.2 Ma,and 405 kyr),stratigraphy(organic-rich mudstone),and paleoclimatic reconstructions(warm and humid climate) provided convincing evidence for the EECO in Kaiping Sag.This study presented the first detailed record of the terrestrial paleoenvironment response to the EECO in the South China Sea,characterized by high terrestrial input,anoxia water conditions,and elevated paleo productivity.A transient pre-warming event before the EECO exhibited a similar paleoenvironmental response,highlighting the sensitivity of terrestrial records.Post-EECO conditions showed a reversal of paleoenviro nmental tre nds observed during the EECO.Pearson correlation analysis reveals that the EECO influenced OM enrichment by regulating paleo productivity and preservation conditions of lake.Elevated atmospheric pCO_(2) levels and increased terrestrial input promoted algal blooms,thereby enhancing lake productivity.OM preservation was controlled by water column stratification and bottom water anoxia,driven by increased terrestrial input and rising lake levels.Our findings enhance the understanding of feedback mechanisms in terrestrial environments during global warming and provide insights into future climate change predictions.展开更多
This study conducts a comparative investigation between short-lived(3-8 days)and long-lived(9-24 days)break events of the South China Sea summer monsoon during 1979-2020,focusing on their statistical characteristics a...This study conducts a comparative investigation between short-lived(3-8 days)and long-lived(9-24 days)break events of the South China Sea summer monsoon during 1979-2020,focusing on their statistical characteristics and potential mechanisms for their different persistence.Results suggest that both types of events are characterized by anomalously suppressed convection accompanied by an anomalous anticyclone during the break period.However,these convection and circulation anomalies exhibit more localized patterns for short-lived events,but possess larger spatial scales and stronger intensities for long-lived events.The influence of tropical intraseasonal oscillations(ISOs)on short-and long-lived events is explored to interpret their different durations.It is found that for short-lived events,the 10-25-day oscillation is dominant in initiating and terminating the break,while the impact of the 30-60-day oscillation is secondary,thus resulting in a brief break period.In contrast,for long-lived events,the 10-25-day oscillation contributes to break development rather than its initiation,and concurrently,the 30-60-day oscillation shows a remarkable enhancement and plays a decisive role in prolonging the break duration.Furthermore,we find that long-lived events are preceded by significant ISO activities approximately two weeks before their occurrence,which can be regarded as efficient predictors.Associated with these precursory ISOs,the occurrence probability of break days for long-lived events can rise up to triple their original probability(35.43%vs.11.21%).展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.42027804,41775026,and 41075012)。
文摘Cirrus clouds play a crucial role in the energy balance of the Earth-atmosphere system.We investigated the spatiotemporal variations of cirrus over the South China Sea(SCS)using satellite data(MOD08,MYD08,CALIPSO)and reanalysis data(MERRA-2)from March 2007 to February 2015(eight years).The horizontal distribution reveals lower cirrus fraction values in the northern SCS and higher values in the southern region,with minima observed in March and April and maxima sequentially occurring in August(northern SCS,NSCS),September(middle SCS,MSCS),and December(southern SCS,SSCS).Vertically,the cirrus fraction peaks in summer and reaches its lowest levels in spring.Opaque cirrus dominates during summer in the NSCS and MSCS,comprising 53.6%and 55.9%,respectively,while the SSCS exhibits a higher frequency of opaque cirrus relative to other cloud types.Subvisible cirrus clouds have the lowest frequency year-round,whereas thin cirrus is most prominent in winter in the NSCS(46.3%)and in spring in the MSCS(45.3%).A case study from September 2021 further explores the influence of ice crystal habits on brightness temperature(BT)over the SCS.Simulations utilizing five ice crystal shapes from the ARTS DDA(Atmospheric Radiative Transfer Simulator Discrete Dipole Approximation)database and the RTTOV 12.4 radiative transfer model reveal that the 8-column-aggregate shape best represents BT in the NSCS and SSCS,while the large-block-aggregate shape performs better in the SSCS.
基金Supported by the National Key Research and Development Program of China(No.2023YFC3008202)the National Natural Science Foundation of China(No.42406019)the Scientific Research Fund of Zhejiang Provincial Education Department(No.Y202353066)。
文摘The prediction of sea surface partial pressure of carbon dioxide(pCO_(2))in the South China Sea is crucial for understanding the region’s contribution to the global carbon budget and its interactions with climate change.We applied the Spatiotemporal Convolutional Long Short-Term Memory(STConvLSTM)model,integrating key environmental factors including sea surface temperature(SST),sea surface salinity(SSS),and chlorophyll a(Chl a),to predict and analyze sea surface pCO_(2)in the South China Sea.The model demonstrated high accuracy in short-term predictions(1 month),with a mean absolute error(MAE)of 0.394,a root mean square error(RMSE)of 0.659,and a coefficient of determination(R^(2))of 0.998.For long-term predictions(12 months),the model maintained its predictive capability,with an MAE of 0.667,RMSE of 1.255,and R^(2)of 0.994.Feature importance analysis revealed that sea surface pCO_(2)and SST were the main drivers of the model’s predictions,whereas Chl a and SSS had relatively minor impacts.The model’s generalization ability was further validated in the northwest Pacific Ocean and tropical Pacific Ocean,where it successfully captured the spatiotemporal variation in pCO_(2)with small prediction errors.The ST-ConvLSTM model provides an efficient and accurate tool for forecasting and analyzing sea surface pCO_(2)in the South China Sea,offering new insights into global carbon cycling and climate change.This study demonstrates the potential of deep learning in marine science and provides a significant technical support for global changes and marine ecosystem research.
基金funded by the South Oil Exploration and Development Company of PetroChina(2021-HNYJ-010).
文摘The Fushan Depression is one of the petroliferous depressions in the Beibuwan Basin,South China Sea.Previous studies have preliminarily explored the origin and source of crude oils in some areas of this depression.Nevertheless,no systematic investigations on the classification and origin of oils and hy-drocarbon migration processes have been made for the entire petroleum system in this depression,which has significantly hindered the hydrocarbon exploration in the region.A total of 32 mudstone and 58 oil samples from the Fushan Depression were analyzed to definite the detailed oil-source correlation within the sequence and sedimentary framework.The organic matter of third member of Paleogene Liushagang Formation(Els(3))source rocks,both deltaic and lacustrine mudstone,are algal-dominated with high abundance of C_(23)tricyclic terpane and C_(30)4-methylsteranes.The deltaic source rocks occur-ring in the first member(Els_(1))and second member(Els_(2))of the Paleogene Liushagang Formation are characterized by high abundance of C_(19+20)tricyclic terpane and oleanane,reflecting a more terrestrial plants contribution.While lacustrine source rocks of Els_(1)and Els_(2)display the reduced input of terrige-nous organic matter with relatively low abundance of C 19+20 tricyclic terpane and oleanane.Three types of oils were identified by their biomarker compositions in this study.Most of the oils discovered in the Huachang and Bailian Els_(1)reservoir belong to group A and were derived from lacustrine source rocks of Els_(1)and Els_(2).Group B oils are found within the Els_(1)and Els_(2)reservoirs,showing a close relation to the deltaic source rocks of Els_(1)and Els_(2),respectively.Group C oils,occurring in the Els3 reservoirs,have a good affinity with the Els3 source rocks.The spatial distribution and accumulation of different groups of oils are mainly controlled by the sedimentary facies and specific structural conditions.The Els_(2)reservoir in the Yong'an area belonging to Group B oil,are adjacent to the source kitchen and could be considered as the favorable exploration area in the future.
基金Guangdong Major Project of Basic and Applied Basic Research(2020B0301030004)National Natural Science Foundation of China(42475003)Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(SML2023SP209)。
文摘Southerly moisture surges over the central South China Sea(SCS)are characterized by the strengthening of lowlevel southerlies that transport moisture northward from the Pacific or Indian Oceans to South China.These surge events typically occur for days in the early-summer season(from April to June)and can lead to heavy rains in South China.This study categorizes surge events into three types of flow patterns and examines their multiscale variations and impacts on rainfall.The first type occurs mainly in April,with the southeasterlies enhanced by a deepening trough in South China and the western Pacific subtropical high established over the SCS.The second type of surge events mostly appears in June,featuring the prevailing southwesterlies of summer monsoon from the Indian Ocean during the active phases of intraseasonal oscillations.Most surge events exhibit semi-diurnal variations with morning and afternoon peaks of northward moisture fluxes.Specifically,the first type features a dominant afternoon peak,while the second type shows a dominant early-morning peak,which is induced by thermal contrast between the Indochina Peninsula and the SCS.In general,the surge events enhance moisture convergence and increase rainfall downstream in South China,but they show some regional differences.The second type strengthens moisture convergence and rainfall in coastal regions with a morning peak.In contrast,the first type enhances inland rainfall with a morning peak,while moisture divergence dominates coastal regions.The third type of surge events denotes transitional conditions between the first two types,in terms of atmospheric circulations,diurnal cycles,and rainfall patterns.These results highlight a diversity of regional moisture surges and related rainfall ranging from diurnal to sub-seasonal scales.
基金financially supported by the National Key Research and Development Program of China(Grant No.2022YFC2806100)the National Natural Science Foundation of China(Grant Nos.U22B20126 and 52374020)+1 种基金Science Foundation of China University of Petroleum,Beijing(Grant No.2462025QNXZ009)Beijing Nova Program(Grant No.20250484913).
文摘Steel catenary riser represents the pioneering riser technology implemented in China’s deep-sea oil and gas opera-tions.Given the complex mechanical conditions of the riser,extensive research has been conducted on its dynamic analysis and structural design.This study investigates a deep-sea oil and gas field by developing a coupled model of a semi-submersible platform and steel catenary riser to analyze it mechanical behavior under extreme marine condi-tions.Through multi-objective optimization methodology,the study compares and analyzes suspension point tension and touchdown point stress under various conditions by modifying the suspension position,suspension angle,and catenary length.The optimal configuration parameters were determined:a suspension angle of 12°,suspension position in the southwest direction of the column,and a catenary length of approximately 2000 m.These findings elucidate the impact of configuration parameters on riser dynamic response and establish reasonable parameter layout ranges for adverse sea conditions,offering valuable optimization strategies for steel catenary riser deployment in domestic deep-sea oil and gas fields.
基金Supported by the Research Project of CNOOC(KJZH-2021-0003-00).
文摘Based on petroleum exploration and new progress of oil and gas geology study in the Qiongdongnan Basin,combined with seismic,logging,drilling,core,sidewall coring,geochemistry data,a systematic study is conducted on the source,reservoir-cap conditions,trap types,migration and accumulation characteristics,enrichment mechanisms,and reservoir formation models of ultra-deep water and ultra-shallow natural gas,taking the Lingshui 36-1 gas field as an example.(1)The genetic types of the ultra-deep water and ultra-shallow natural gas in the Qiongdongnan Basin include thermogenic gas and biogenic gas,and dominated by thermogenic gas.(2)The reservoirs are mainly composed of the Quaternary deep-water submarine fan sandstone.(3)The types of cap rocks include deep-sea mudstone,mass transport deposits mudstone,and hydrate-bearing formations.(4)The types of traps are mainly lithological,and also include structural-lithological traps.(5)The migration channels include vertical transport channels such as faults,gas chimneys,fracture zones,and lateral transport layers such as large sand bodies and unconformity surfaces,forming a single or composite transport framework.A new natural gas accumulation model is proposed for ultra-deep water and ultra-shallow layers,that is,dual source hydrocarbon supply,gas chimney and submarine fan composite migration,deep-sea mudstone-mass transport deposits mudstone-hydrate-bearing strata ternary sealing,late dynamic accumulation,and large-scale enrichment at ridges.The new understanding obtained from the research has reference and enlightening significance for the next step of deepwater and ultra-shallow layers,as well as oil and gas exploration in related fields or regions.
基金Supported by the National Natural Science Foundation of China(No.42077143)the Young Top-notch Talent Cultivation Program of Hubei Province,Outstanding Young and Middle-aged Science and Technology Innovation Team Project of the Hubei Provincial Department of Education(HPDE)(No.T2020016)the Training Fund Program for Scientific Research of Hubei University of Arts and Science(No.2020KYPYTD005)。
文摘The environmental impact of microplastic pollution has triggered the alarm of public for over 20 years.The South China Sea,situated as a marginal sea in the tropical region,is surrounded by unique blue-carbon ecosystems and densely populated provinces that produce a substantial amount of industrial plastic waste.Understanding the source-sink relationship and distribution of microplastics in rivers,nearshores,and estuaries is crucial for safeguarding the ecological integrity of estuarine environments.In this review,a comprehensive review of recent researches on the distribution and source-sink relationships of microplastics in rivers and nearshore and offshore regions in the South China Sea have been discussed.Due to atmospheric deposition and precipitation,microplastics exhibit spatial heterogeneity in terms of abundance and distribution in areas surrounding the South China Sea.The major pollution sources include river inputs,industrial wastewater discharge,aquaculture activities,and shipping operations.Anthropogenic and other biological factors such as fish ingestion and vegetation entrapment also affect the distribution and transport of microplastics.To quantify the abundance and distribution of microplastics and elucidate their transport mechanisms,it is recommended to strengthen the detection and management of microplastics in the South China Sea region,standardize sampling methods and units,establish shared databases,and explore effective governance pathways.
基金The National Natural Science Foundation of China under contract Nos T2261149752 and 42476172the Open Funding of the Technology Innovation Center for South China Sea Remote Sensing,Surveying and Mapping Collaborative Application,Ministry of Natural Resources,P.R.China under contract No.RSSMCA-2024-B001。
文摘High-accuracy Sea level prediction is important for understanding marine environments and climate change.In this work,a deep convolutional neural network(CNN)combined with attention mechanism(ADNN)is established for sea level anomaly(SLA)prediction from historical satellite observations.Multi-year(1998-2020)radar altimetry observed SLA pattern samples in the South China Sea are used for model training and testing.Compared with existing deep learning models such as CNN and convolutional long short-term memory(ConvLSTM)network,ADNN demonstrates the highest accuracies of 94.0%,91.1%,88.4%and 86.2%for 1-d,3-d,5-d and 7-d SLA field predictions,with regional average root mean square errors(RMSE)of 0.27 cm,0.51 cm,0.80 cm and 1.09 cm,respectively.The integration of CNN and attention mechanism significantly improves the model performance,especially in estimating short-term sea level changes,with a 74.7%reduction in the RMSE for 1-d predictions compared to the baseline CNN model.Comparative experiments also show that the ADNN model performs well when the input data contains a certain degree of noise.Moreover,a multivariate ADNN(M-ADNN)model is designed to investigate the impacts of environmental variables such as sea surface temperature(SST)and wind on SLA prediction.The model yields a slightly higher accuracy but the results are quite similar to those of the ADNN model.The findings suggest that,although SST or wind can affect sea level changes,the ADNN model demonstrates the ability to identify and learn sufficient information about sea level changes solely from satellite altimetry measurements of SLA,especially for relatively long-term(≥5 d)predictions.This eliminates the need for additional input parameter data,thereby improving the SLA prediction efficiency.
基金supported financially by the National Natural Science Foundation of China[grant numbers 42027804,41775026,and 41075012]。
文摘Studying the characteristics and mechanisms of convective and non-convective cirrus clouds over the South China Sea is vital for their impact on regional climate dynamics,and enhancing predictive models for weather and climate forecasts.This study utilizes eight years of CALIPSO data(from March 2007 to February 2015)to investigate convective and non-convective cirrus clouds.Explicit new insights include the observation that convective cirrus cloud samples are three times more numerous than non-convective cirrus clouds.Convective cirrus clouds are associated with humid conditions and demonstrate higher ice water content(IWC)values ranging from 10^(−3)to 10^(−1)g m^(−3),whereas non-convective cirrus clouds tend to be drier,exhibiting IWC values ranging from 10^(−4)to 10^(−3)g m^(−3).Both cirrus cloud types exhibit a maximum cloud fraction at 10°N.Convective cirrus reach their peak cloud fraction at an altitude of 14 km,while non-convective cirrus typically occur at altitudes between 15 and 16 km.The seasonal variability of the convective cirrus cloud fraction primarily reflects bottom-up positive specific humidity anomalies originating from convective activity,whereas the non-convective cirrus cloud fraction is influenced by top-down negative temperature anomalies.
基金The National Key Research and Development Program of China under contract No.2023YFC3107704the Basic Scientific Fund for National Public Research Institutes of China under contract No.2022Q08+1 种基金the National Natural Science Foundation of China under contract No.42576216the“Research on Deep Water Marine Environment Monitoring and Data Platform”Project of Beijing Research Center of CNOOC(China)Co.,Ltd.under contract No.KJGG2022-0202.
文摘Extreme wind events in the South China Sea(SCS)directly threaten maritime safety.With climate change altering their patterns,frequency,and intensity,understanding these changes is increasingly important.This study systematically investigates their spatiotemporal characteristics using high-resolution ERA5 reanalysis data from 1940 to 2023.The climatological wind speed exhibits a bimodal structure,with northeast winds dominating in winter and southwest winds prevalent in summer.During 1940−2023,the annual mean wind speed shows a modest upward trend of 0.01±0.02 m/s per decade,with notable seasonal and spatial variation.These changes in mean-state wind conditions strongly influence extreme wind(EW95)events,defined as daily maximum wind gusts exceeding the local 95th percentile.The EW95 events occur about 16 d annually,with typical speeds reaching 18.8 m/s.The spatial distribution of EW95 frequency displays an inverse relationship with intensity which closely aligns with climatological wind patterns.Seasonally,frequency peaks in December,matching the climatological wind speed,while peak intensity occurs in October and resurges in April,indicating decoupled seasonal patterns between frequency and intensity.Over the study period,EW95 events have become both more frequent and intense.Frequency increased by(0.71±0.37)d/a per decade,while intensity rose by(0.06±0.05)m/s per decade outpacing mean wind speed changes.Seasonal trends reveal a growing concentration of EW95 events in winter,with intensified events in late spring and late summer,despite decreased frequencies during these periods.These findings highlight significant changes in extreme winds behavior in the SCS under climate change,offering valuable insights for risk management and adaptation strategies.
基金The National Natural Science Foundation of China under contract No.42030502the Guangxi Scientific Projects under contract Nos.AD17129063,AA17204074,and 2025GXNSFAA069324the NSFC project under contract No.42166003。
文摘As one of the micro-blocks dispersed in the South China Sea(SCS),the Xisha Islands are covered by thick Cenozoic sedimentary layers,making it challenging to obtain magmatic rocks.Well CK-2 is a kilometer-scale scientific drilling project on the Xisha Islands in the northwestern SCS.It penetrates the thick reef limestone and reaches basaltic pyroclastic rocks.This study presents the whole-rock and olivine compositions of the basaltic volcaniclastic rocks from Well CK-2.These rocks exhibited ocean island basalt signatures characterized by the enrichment of light rare earth elements and high-field-strength elements.Compared with partial melting products derived from mantle peridotite,whole-rock compositions showed elevated Fe/Mn and Zn/Fe mass ratios.Additionally,olivines were characterized by a lower Ca content,higher Ni content,elevated Fe/Mn mass ratios,and moderate Mn/Zn mass ratios compared to those crystallized from peridotitic melts.The compositions of both the whole-rock and olivine phenocrysts indicate the presence of pyroxenite in the mantle source,which likely formed through the reaction of recycled oceanic crust with the surrounding mantle peridotite.Using the olivine-liquid Mg-Fe exchange thermometer,this study derived mantle potential temperatures(T_(p))ranging from 1502℃to 1756℃,which is consistent with those of plume-related ocean island basalts.Furthermore,the basaltic volcaniclastic rocks exhibit low H_(2)O contents(0.01%–1.47%),which were significantly lower than those found in the primary magmas of Large Igneous Provinces.These results suggest that the basaltic volcaniclastic rocks on the Xisha Islands originated from a volatile-poor mantle plume source.
基金supported by the Guangdong Pearl River Talent Program(No.017TZ07Z066)the Second Tibetan Plateau Scientific Expedition and Research Program(No.2019QZKK0701)+4 种基金the Southern Marine Laboratory(Zhuhai)Innovative R&D Program(No.311021003)the National Natural Science Foundation of China(No.42106067)the Natural Science Foundation of Guangdong Province,China(No.2022A1515010090)Shanghai Sheshan National Geophysical Observatory(No.SSOP202102)Guangzhou Science and Technology Planning Project(No.202102020456).
文摘Magmatism at continental margins is of great significance in understanding the continental rifting.We present a twodimensional P-wave velocity model derived from an ocean bottom seismometer experiment,conducted across the middle northern continental margin of the South China Sea(SCS).The detailed velocity structures reveal significant heterogeneities extending from the continental shelf to the continent-ocean transition zone.The crust exhibits its greatest thickness below the continental shelf,measuring~23 km and gradually thins to~13 km at the distal margin.Furthermore,a narrow and distinct continent-ocean transition with only 40-km width is revealed.We also observe a high-velocity layer within the transition zone,reaching thickness of up to 4 km,characterized by P-wave velocities ranging from 7.0 km/s to 7.6 km/s in the lower crust.Based on the syn-rift melt generation using decompression melting model,we ascertain that syn-rift magmatism cannot fully account for the observed thick high-velocity layer.By integrating findings from previous geophysical and geochemical studies presenting extensive volcanic edifice on the seafloor at the northern margin,as well as ocean-island-basalt-type magmaticsamples in the SCS area,we propose that post-rifting magmatism associated with the Hainan Plume may have influenced theformation of the high-velocity lower crust within the transition zone and the northern margin of the SCS can thus be recognizedas magma-poor type margin.
基金supported by the National Key Research and Development Program of China[grant number 2022YFF0801701]the National Natural Science Foundation of China[grant number 42105017].
文摘The South China Sea winter monsoon(SCSWM),an integral component of the East Asian winter monsoon,connects extratropical and tropical regions.Utilizing ERA5 reanalysis and PAMIP simulations,the relationship between Arctic sea ice and the SCSWM is investigated.The authors reveal that its strongest relationship with Arctic sea ice occurs in the North Pacific sector,i.e.,the Sea of Okhotsk and western Bering Sea.This link persists throughout the cold season,peaks when sea ice precedes the SCSWM by one month,and is independent of ENSO.North Pacific sea-ice loss weakens the meridional temperature gradient(MTG)and vertical wind shear in midlatitudes,reducing baroclinic eddy formation.Given the reduced zonal wind according to the thermal wind relation,the reduced wave activity flux in the upper troposphere must be balanced by equatorward wind based on the quasi-geostrophic momentum equation.This generates an anomalous meridional overturning circulation with descent and low-level divergence around 30°N,which intensifies the divergent component of the SCSWM.The divergent northerly anomalies also lead to cold advection and subtropical cooling.The enhanced MTG due to the subtropical cooling and weakened MTG due to high-latitude warming closely tied to reduced North Pacific sea ice displace the westerly jet southward,creating cyclonic shears over the North Pacific and intensifying the rotational component of the SCSWM.These findings establish North Pacific sea ice as a non-ENSO driver of the SCSWM,holding substantial implications for the predictability of the SCSWM.
基金The Guangxi Science and Technology Program under contract No.AD25069075the National Natural Science Foundation of China under contract No.42276182+2 种基金the Major Talent Project of Guangxi Zhuang Autonomous Region under contract No.GXR-2BGQ2525027the Natural Science and Technology Innovation Development Doubling Program of Guangxi University under contract No.2023BZRC019the Guangxi Natural Science Foundation of China under contract No.2022GXNSFAA035548.
文摘Analyzing coral reef topography is critical for understanding both the formation mechanisms of coral reefs and coral spatial distribution patterns.However,most topographic studies have focused on small-scale or localized survey sites,and investigations of reef macro-topography patterns and their relationship with coral distribution are scant.To address this gap,we conducted a comprehensive investigation of macro-topographic patterns across 12 coral reefs covering 607 km2 in the Xisha Islands,South China Sea.Using digital elevation models constructed from satellite bathymetric data with 16 m resolution,we analyzed spatial variations of seven topographic indices at the reef,geomorphic zone,and reef slope orientation levels in shallow waters.Field surveys were integrated with topographic indices to interpret and model coral distribution patterns.Our results revealed significant topographic heterogeneity,particularly in reef slopes and lagoon patch reefs.Reef slopes ranged from 0°to 33°,with rugosity values between 1.00 and 1.19.The steepness of reef slopes varied by orientation,being steepest in the west,southwest,and south,while the consistency of slope gradients was highest in the south,east,and northeast.Furthermore,stress-tolerant coral cover on reef slopes was effectively predicted by the factors of topographic indices,water depth,and slope aspect.Additionally,the topographic changes in reef flats and shallow lagoons were minimal.These findings advance our understanding of coral reef formation mechanisms in the Indo-Pacific region and provide a theoretical foundation for the conservation and restoration of coral reef ecosystems.
基金The Natural Science Foundation of Jiangsu Province under contract No.BK20210885the National Natural Science Foundation of China under contract Nos 52372356,52371277,and 42076005.
文摘Based on year-long mooring observations(January-December 2013)near the Xisha Islands in the northwestern South China Sea,this study investigates the characteristics of typhoon-induced near-inertial waves(NIWs)during three events(typhoons Wutip,Nari,and Haiyan).The influence of mesoscale eddies on NIWs and the interaction between NIWs and internal tides(ITs)were analyzed.Notably,near-inertial kinetic energy(NIKE)increased significantly following typhoon Haiyan,reaching a peak value of 40.60 J/m^(3),the highest recorded NIKE in 2013.This value was approximately threefold and fivefold larger than those generated by typhoons Wutip and Nari,respectively.NIKE generated by all three typhoons exhibited downward radiation.Power spectral analysis revealed significant frequency shifts in NIWs during each typhoon,with shifts linked to mesoscale eddies present at the observation site.Additionally,bicoherence analysis reveals that the fD_(1)(f+D_(1))and D_(2)−f waves(where f is the local inertial frequency,and D1 and D_(2)denote the frequencies of diurnal and semidiurnal ITs,respectively)in the power spectrum originate from the nonlinear interactions between NIWs and ITs during typhoons Wutip and Haiyan.Temporal analysis of kinetic energy and shear showed that the enhancement of nonlinear coupling between NIWs and ITs was primarily driven by the strong NIWs with strong vertical shear.This study provides valuable insights into the generation,propagation,and interaction of NIWs and ITs,contributing to a deeper understanding of ocean mixing processes in response to different typhoon conditions.
基金The National Natural Science Foundation of China under contact No.41905006the Natural Science Foundation from Guangdong Basic and Applied Basic Research Foundation Meteorological Joint Fund under contact Nos 2024A1515510034 and 2025A1515510014+1 种基金the Guangdong Provincial Observation and Research Station for Tropical Ocean Environment in Western Coastal Waters(GSTOEW)and the Key Construction Discipline of High-level Universities-Marine Science under contact Nos 231420003 and 080503032101the Innovative Team Plan for Department of Education of Guangdong Province under contact Nos 2023KCXTD015 and 2024KCXTD042.
文摘The sea surface temperature(SST)front over the northern South China Sea(NSCS)has significant impacts on regional weather,climate,and marine ecology.Based on high-resolution satellite data and reanalysis data,the long-term variation characteristics and possible mechanisms of the SST front intensity(SSTFI)over the NSCS in winter from 1986 to 2020 are analyzed.The results show that:(1)Based on empirical orthogonal decomposition analysis,the evolution features of SST front mainly include two types:position shift type and an intensity variation type.(2)The SSTFI is accelerating in recent two decades.From 1986 to 2003(P1),the SSTFI changed relatively smoothly[0.2℃/(km·decade)],while from 2004 to 2020(P2),there is a significant strengthening trend[1.2℃/(km·decade)].(3)The horizontal advection related to the ocean current dominates the intensification of the SST front.An anomalous cyclonic circulation in upper ocean of the NSCS and the coastal current of South China strengthen the cold advection,resulting in cooling of the coastal waters of South China.(4)The latent heat flux dominates the sea surface heat loss and cooling process,but both latent and sensible heat flux are not conducive to the enhancement of the SSTFI.(5)The increase in SSTFI is largely associated with La Niña-like pattern,which is conducive to enhance the East Asia winter monsoon,and strengthens the ocean front through air-sea interactions.This study provides a scientific reference for understanding the variations of the SSTFI.
基金National Natural Science Foundation of China(42175018, 42175020)Science and Technology Planning Project of Guangdong Province (2023B1212060019)+1 种基金Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai)(311024001)Project supported by Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai)(SML2023SP209)。
文摘This study explores the impact of the tropical sea surface temperature(SST) independent of the preceding winter El Nino–Southern Oscillation(ENSO) events(ENSO-independent SST) on the interannual variability of the South China Sea Summer Monsoon(SCSSM) and the associated mechanisms. During summer, the ENSO-independent SST component dominates across tropical ocean regions. The tropical ENSO-independent SSTs during spring and summer in the Maritime Continent(MC), the equatorial central-eastern Pacific(CEP), and the tropical Atlantic Ocean(TAO) regions play a comparably significant role in the interannual variation of the SCSSM intensity, compared to the tropical SST dependent on the preceding winter ENSO. The ENSO-independent SST anomalies(SSTA) in the TAO during spring and summer exhibit significant persistence. They can influence the SCSSM through westward propagation of teleconnection, as well as through eastward-propagating Kelvin waves. In summer, the SSTA in the MC, CEP, and TAO regions contribute jointly to the variability of the SCSSM. The MC SSTA affects local convection and generates anomalous meridional circulation to impact the SCSSM intensity. The CEP SSTA directly influences the SCSSM via the Matsuno-Gill response mechanism and indirectly affects it via meridional circulation by modulating vertical motions over the MC through zonal circulation. The TAO SSTA impacts the SCSSM through both westward and eastward pathways, as well as by influencing zonal circulation patterns in the tropical and subtropical North Pacific. The results offer valuable insights into the factors influencing the interannual variability of the SCSSM intensity.
基金Long-Term Research Grant Scheme (LRGS:56041)Interaction of Ocean Dynamics With The Climate System of Past,Present,and Future Using Ocean Observation Integrated Data and Numerical Modeling。
文摘Using literature published from 2010 onwards, this study investigates the ~3 500 km extension of the shallow shelf current in the South China Sea(SCS) during the winter and summer monsoons. This current is later acknowledged as the South China Sea shallow shelf Current(SCSSC). This current is primarily driven by monsoonal winds, and influenced by regional river plumes [Zhujiang(Pearl) River, Hong River, Mekong River] and the prominent South China Sea Warm Current(SCSWC) and South China Sea Western Boundary Current(SCSWBC). The current exhibits significant seasonal variations in both direction and pattern. During winter, it flows along the northern South China Sea's(NSCS) shelf and splits into two branches at the east of Hainan Island. One branch enters the Beibu Gulf through the Qiongzhou Strait and forms a major cyclonic circulation within the gulf, while the other branch flows southwestward along the southern coast of Hainan Island. These branches converge around 16°N latitude at the east of the Vietnamese shelf, then flow southward along the Sunda Shelf, where they deflect southwestward in “broadband”forms before curving southeastward along the east coast of Peninsular Malaysia(ECPM) and exiting via the Karimata Strait. In summer, the current exhibits a complex pattern. At the Sunda Shelf, it flows northwestward along the ECPM,then deflects northeastward around 6°N latitude, forming the Sunda Shelf's anti-cyclonic eddy(SSE) and causing upwelling on the east coast of Peninsular Malaysia(ECPMU). Near the eastern Vietnamese shelf, the current splits around 11°-12°N latitude into three distinct currents: the southward-flowing Vietnam Current, the northward-flowing Vietnam Meandering Current(VMC), and the southward-flowing SCSWBC. The VMC flows northward and then deflects northeastward south of Hainan Island, continuing northeastward along the NSCS's shelf and exiting through the Taiwan Strait.
基金funded by the National Natural Science Foundation of China (42372147)State Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum (Beijing) for their support of this research。
文摘The Early Eocene Climate Optimum(EECO) represents the peak of the early Paleogene greenhouse climate.However,a comprehensive understanding of the terrestrial paleoenvironmental response to the EECO and its implications for organic matter(OM) enrichment remains lacking.We integrated sedimentological,astrochronological,and geochemical data from South China Sea sediments to reconstruct the paleoenvironment and establish the OM enrichment model during the EECO.Astronomical time scales(ATS) for the Lower Wenchang Formation(Lower WC Fm.) in the Kaiping Sag,South China Sea,were established,spanning 55.4 to 43.9 Ma.During 51.5-48.7 Ma,records of astronomical signal(with overlapping cycles of 2.4 Ma,1.2 Ma,and 405 kyr),stratigraphy(organic-rich mudstone),and paleoclimatic reconstructions(warm and humid climate) provided convincing evidence for the EECO in Kaiping Sag.This study presented the first detailed record of the terrestrial paleoenvironment response to the EECO in the South China Sea,characterized by high terrestrial input,anoxia water conditions,and elevated paleo productivity.A transient pre-warming event before the EECO exhibited a similar paleoenvironmental response,highlighting the sensitivity of terrestrial records.Post-EECO conditions showed a reversal of paleoenviro nmental tre nds observed during the EECO.Pearson correlation analysis reveals that the EECO influenced OM enrichment by regulating paleo productivity and preservation conditions of lake.Elevated atmospheric pCO_(2) levels and increased terrestrial input promoted algal blooms,thereby enhancing lake productivity.OM preservation was controlled by water column stratification and bottom water anoxia,driven by increased terrestrial input and rising lake levels.Our findings enhance the understanding of feedback mechanisms in terrestrial environments during global warming and provide insights into future climate change predictions.
基金supported by the National Natural Science Foundation of China(Grant No.42275025)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2023084).
文摘This study conducts a comparative investigation between short-lived(3-8 days)and long-lived(9-24 days)break events of the South China Sea summer monsoon during 1979-2020,focusing on their statistical characteristics and potential mechanisms for their different persistence.Results suggest that both types of events are characterized by anomalously suppressed convection accompanied by an anomalous anticyclone during the break period.However,these convection and circulation anomalies exhibit more localized patterns for short-lived events,but possess larger spatial scales and stronger intensities for long-lived events.The influence of tropical intraseasonal oscillations(ISOs)on short-and long-lived events is explored to interpret their different durations.It is found that for short-lived events,the 10-25-day oscillation is dominant in initiating and terminating the break,while the impact of the 30-60-day oscillation is secondary,thus resulting in a brief break period.In contrast,for long-lived events,the 10-25-day oscillation contributes to break development rather than its initiation,and concurrently,the 30-60-day oscillation shows a remarkable enhancement and plays a decisive role in prolonging the break duration.Furthermore,we find that long-lived events are preceded by significant ISO activities approximately two weeks before their occurrence,which can be regarded as efficient predictors.Associated with these precursory ISOs,the occurrence probability of break days for long-lived events can rise up to triple their original probability(35.43%vs.11.21%).
