Trend of Storm Surge Induced by Typical Landfall Super Typhoons During 1975–2021 in the Eastern China Sea

Climate change affects the activity of global and regional tropical cyclones(TCs).Among all TCs,typical super typhoons(STYs)are particularly devastating because they maintain their intensity when landing on the coast and thus cause casualties,economic losses,and environmental damage.Using a 3D tidal model,we reconstructed the typhoon(TY)wind field to simulate the storm surge induced by typical STYs.The TY activity was then analyzed using historical data.Results showed a downtrend of varying degrees in the annual frequency of STYs and TCs in the Western North Pacific(WNP)Basin,with a significant trend change observed for TCs from 1949 to 2021.A large difference in the interannual change in frequency was found between STYs and TCs in the WNP and Eastern China Sea(ECS).Along the coast of EC,the frequency of landfall TCs showed a weak downtrend,and the typical STYs showed reverse micro growth with peak activity in August.Zhejiang,Fujian,and Taiwan were highly vulnerable to the frontal hits of typical STYs.Affected by climate change,the average lifetime maximum intensity(LMI)locations and landfall locations of typical STYs in the ECS basin showed a significant poleward migration trend.In addition,the annual average LMI and accumulated cyclone energy showed an uptrend,indicating the increasing severity of the disaster risk.Affected by the typical STY activity in the ECS,the maximum storm surge area also showed poleward migration,and the coast of North China faced potential growth in high storm surge risks.

The mapping methods and division of tectonic units of the regional tectonic map in the eastern China seas and adjacent regions

The geological-geophysical map series of the eastern China seas and adjacent region （1：1 000 000） will be published in the late half year of 2009. The regional tectonic map is one of the main professional maps. The Mapping methods, the division method of geological tectonic units and the main geological tectonic units are mainly discussed. The strata from Pliocene to Holocene are peeled off so as to display the Pre-Pliocene structures. In basins, isopaches are drawn for the Cenozoic deposits. The plate tectonic theory and present tectonic pattern are adopted as the priorities in tectonic division. As to the division of intraplate tectonic units, it is a revision, complement and improvement of previous dividing systems, and the nomenclature for each tectonic unit follows the current system in China. The first-order tectonic unit is plate （Pacific Plate, Eurasian Plate and Philippine Sea Plate）. The second-order tectonic unit is tectonic domain （East Asian continental tectonic domain,East Asian continental margin tectonic domain and west Pacific tectonic domain）. The Philippine Sea Plate and the west part of the Pacific Plate are called the West Pacific tectonic domain. The part of the Eurasian Plate involved in this study area can be further divided into East Asian continental tectonic domain and East Asian continental margin tectonic domain. The East Asian continental margin domain is composed of the Ryukyu island arc, the Okinawa Trough back-arc basin and the back-arc basin of Sea of Japan. The East Asian continental tectonic domain in this study area is composed of the Sino-Korea Massif, the Changjiang River （Yangtze） Massif and South China Massif. In turn, these massifs consist of basins, folded belts or uplift zones. The basins,the folded belts or the uplift zones are further divided into uplifts and depressions made up of sags and swells.

Study on numerical simulation and dynamic mechanism of win-ter- time circulation in the eastern China seas

An MOM2 based 3-dimentional prognostic baroclinic Z-ordinate model was established to study the circulation in eastern China seas, considering the topography, inflow and outflow on the open boundary, wind stress, temperature and salinity exchange on the sea surface. The results were consistent with observation and showed that the Kuroshio intrudes in large scale into the East China Sea continental shelf East China, during which its water is exchanged ceaselessly with outer sea water along Ryukyu Island. The Tsushima Warm Current is derived from several sources, a branch of the Kuroshio, part of the Taiwan Warm Current, and Yellow Sea mixed water coming from the west of Cheju Island. The water from the west of Cheju Island contributes ap-proximately 13% of the Isushima Warm Current total transport through the Korea Strait. The circulation in the Bohai Sea and Yellow Sea is basically cyclonic circulation, and is comprised of coastal currents and the Yellow Sea Warm Current. Besides simulation of the real circulation, numerical experiments were conducted to study the dynamic mechanism. The numerical experiments indicated that wind directly drives the East China Sea and Yellow Sea Coastal Currents, and strengthens the Korea Coastal Current and Yellow Sea Warm Current. In the no wind case, the kinetic energy of the coastal current area and main YSWC area is only 1% of that of the wind case. Numerical experiments also showed that the Tsushima Warm Current is of great importance to the formation of the Korea Coastal Current and Yellow Sea Warm Current.

Multi-scale wavelet analysis of TOPEX/Poseidon altimeter significant wave height in eastern China seas

The multi-scale characteristics of wave significant height （Hs） in eastern China seas were revealed by multi-scale wavelet analysis. In order to understand the relation between wave and wind, the TOPEX/Poseidon measurements of Hs and wind speed were analyzed. The result showed that Hs and wind speed change in multi-scale at one-, two-month, half-, one- and two-year cycles. But in a larger time scale, the variations in Hs and wind speed are different. Hs has a five-year cycle similar to the cycle of ENSO variation, while the wind speed has no such cycle. In the time domain, the correlation between Hs and ENSO is unclear.

Upper-ocean temperature trends in the Eastern China Seas during 1976–1996

Temperature in the Eastern China Seas(ECS), including the Bohai, Yellow, and East China seas, is crucially important with regard to weather forecasting and fishery activities of adjacent countries. Although sea surface temperature(SST) in the ECS has demonstrated a dramatically accelerated trend of warming after a regime shift(1976–1996), trends beneath the surface remain poorly understood because of the sparsity of observations. This study used in situ hydrographic data from 1976 to 1996 to examine upperocean temperature trends in the ECS. It was found that the multilevel trends show consistency with that of the surface water; i.e., warming is faster in winter than summer. However, the magnitudes of the trends weaken with increasing depth. Furthermore, the seasonal dif ference in the upper ocean is mainly associated with the warm currents in the ECS, which implies an essential contribution from horizontal advection. These phenomena could also be detected from data acquired from the routinely observed PN and 34°N sections. The spatiotemporal patterns of temperature trends in the upper ECS extend our understanding beyond the SST, especially highlighting the role of ocean dynamics in forming temperature patterns beneath the surface in comparison with atmospheric ef fects.

Modern sea level changes of the Eastern China Seas and their influences on coastal areas

The statistics of tidal gauging records showed that the mean sea level of the China Seas has risen for 14 cm in past 100 years. The annual mean sea levels of the Eastern China Seas have been rising at a speed of about 0.21 -0.23 cm/a since 1960. The annual mean sea levels of the Eastern China Seas in 1989 were 1.45 cm higher than that in 1988 on average.The sea level rise may cause the damage of the dynamical balance of the natural environments in the coastal area? and form or strengthen many coastal disasters, such as storm-tide catastrophic events, sea water invasion landward, soil salinization in coastal lowland and plains, and beach erosion retreat.

CHARACTERISTICS OF EOLIAN DUST OVER THE EASTERN CHINA SEAS

Eolian dust is an important material source of marine sediment and heavy metals influencing marine environment and primary productivity. Although the eastern China Seas and their adjacent regions are downwind of East Asian dust sources and have potentially high atmospheric input, study on the eolian dust in these regions is limited. This study on the compositions of eolian dust indicated that dust concentration and particle sizes varied with seasons and meteorologic conditions, that mineral and chemical compositions have significant regional variation, and that high Fe content is one of the characteristics of eolian dust which was found to be a mixture of natural loess and/or soil and anthropogenic matter that contained fairly high S and heavy metals.

Distribution, burial fluxes and carbon sink effect of sedimentary organic carbon in the eastern China seas

The ocean is the largest active carbon reservoir on Earth. Organic carbon(OC), as the primary species of carbon sequestration in the ocean, plays an important role in the global carbon cycle through its deposition and burial. In this study,sedimentary OC data from 5796 stations, together with relevant geochemical and sedimentological parameters in the Bohai Sea,Yellow Sea, and East China Sea(BYES) were used to summarize and elucidate the distribution and burial patterns of sedimentary OC, and assess carbon sink effect of sedimentary OC burial. The results show that the OC content in the sediments of the BYES ranges from 0.00% to 2.12%, with an average content of 0.47%±0.26%. OC content is significantly correlated with finegrained sediments, with an average OC content in mud areas being 39% higher than that in non-mud areas. Modern OC buried in the BYES are mainly deposited in 7 major mud areas, with a total sedimentary OC burial flux of approximately 8.20 Mt C yr^(–1).Among them, the burial flux of biospheric OC is 6.92 Mt C yr^(–1), equivalent to the OC consumption amount of silicate weathering of the 9 major river basins in the eastern China. In its natural state, the annually sequestered OC in the sediments of the eastern China seas is equivalent to 25.37 Mt of atmospheric CO_(2), indicating a significant carbon sink effect. The distribution and burial of terrigenous OC in the BYES are mainly influenced by the large river inputs and complex marine hydrodynamic environment,while human activities such as dam construction have significantly altered the OC burial in these coastal mud areas.

Eddy analysis in the Eastern China Sea using altimetry data

Statistical characteristics of mesoscale eddies in the Eastern China Sea （ECS） are analyzed using altimetry sea surface height anomaly （SSHA） data from 1993 to 2010. A velocity geometry-based automated eddy detection scheme is employed to detect eddies from the SSHA data to generate an eddy data set. About 1,096 eddies （one lifetime of eddies is counted as one eddy） with a lifetime longer than or equal to 4 weeks are identified in this region. The average lifetime and radius of eddies are 7 weeks and 55 km, respectively, and there is no significant difference between cyclonic eddies （CEs） and anticyclonic eddies （AEs） in this respect. Eddies＇ lifetimes are generally longer in deep water than in shallow water. Most eddies propagate northeastward along the Kuroshio （advected by the Kuroshio）, with more CEs generated on its western side and AEs on its eastern side. The variation of the Kuroshio transport is one of the major mechanisms for eddy genesis, however the generation of AEs on the eastern side of the Kuroshio （to the open ocean） is also subject to other factors, such as the wind stress curl due to the presence of the Ryukyu Islands and the disturbance from the open ocean.

HORIZONTAL AND VERTICAL DISTRIBUTIONS OF CLOUD COVER OVER EASTERN CHINA AND THE EAST CHINA SEA

Based on data from satellite and surface observations,the horizontal and vertical distributions of clouds over eastern China and the East China Sea are examined.Three maximum centers of cloud cover are clearly visible in the horizontal distribution of total cloud cover.Two of these maxima occur over land.As the clouds mainly originate from the climbing airflows in the southern and eastern slopes of the Tibetan Plateau,they can be classified as dynamic clouds.The third center of cloud cover is over the sea.As the clouds mainly form from the evaporation of the warm Kuroshio Current,they can be categorized as thermodynamic clouds.Although the movement of the cloud centers reflect the seasonal variation of the Asian summer monsoon,cloud fractions of six cloud types that are distinct from the total cloud cover show individual horizontal patterns and seasonal variations.In their vertical distribution,cloud cover over the land and sea exhibits different patterns in winter but similar patterns in summer.In cold seasons,limited by divergent westerlies in the middle troposphere,mid-level clouds prevail over the leeside of the Tibetan Plateau.At the same time,suppressed by strong downdraft of the western Pacific subtropical high,low clouds dominate over the ocean.In warm seasons both continental and marine clouds can penetrate upward into the upper troposphere because they are subject to similar unstable stratification conditions.

Bottom water temperature measurements in the South China Sea,eastern Indian Ocean and western Pacific Ocean

文章报道了一批新的海底底水温度(BWT)数据,其中南海(SCS)158个站位、东印度洋(EIO)30个站位及西太平洋(WPO)37个站位。基于这批新的BWT数据,获得南海和西太平洋海域底水温度与水深经验关系,可为地球物理和物理海洋提供准确、可靠的海底温度边界。这将有助于海底油气资源调查与评估。同时,这批实测数据表明:1)水深超过3500m的海域,其底水温度在南海约为2.47℃,比东印度洋(～1.34℃)和西太平洋(～1.60℃)稍微偏高。这与大洋传送带模式所预测的情况比较吻合。该模式认为:低温高盐的海水,从北大西洋格陵兰岛和冰岛附近海域下沉到深层,然后向南流动,再与南极洲周围海域的低温高盐海水一同向北进入印度洋和太平洋。而南海是一个相对比较封闭的热带边缘海,其内部海水与印度洋和菲律宾海交换有限,导致海水温度整体高于印度洋和太平洋。2)台西南盆地水深在2700～3000m的部分站位,其底水温高达约3.00℃,明显高于其周边同水深海域底水温度(平均值约为2.33℃)。这可能是台西南盆地海底水热活动导致的结果。3)在东印度洋和西太平洋水深超过4800m海域,底水温度随着水压增大稍有升高,其升高率分别为10.6mK·MPa^(-1)和12.0mK·MPa^(-1)。这与理论估算的深层底水绝热压力温度梯度范围较为吻合。这也意味着东印度洋和西太平洋深层底水,主要由绝热自压作用导致其温度随着深度的增大而升高。

Recent Trends in Satellite-Derived Chlorophyll and Aerosol Optical Depth Together with Simulated Dimethylsulfide in the Eastern China Marginal Seas

The biogenic compound dimethylsulfide(DMS)produced by a range of marine biota is the major natural source of re-duced sulfur to the atmosphere and plays a major role in the formation and evolution of aerosols,potentially affecting climate.The spatio-temporal distribution of satellite-derived chlorophyll_a(CHL)and aerosol optical depth(AOD)for the recent years(2011-2019)in the Eastern China Marginal Seas(ECMS)(25°-40°N,120°-130°E)are studied.The seasonal CHL peaks occurred during late April and the CHL distribution displays a clear zonal gradient.Elevated CHL was also observed along the northern and western coastlines during summer and winter seasons.Trend analysis shows that mean CHL decreases by about 10%over the 9-year study period,while AOD was higher in south and lower in north during summertime.A genetic algorithm technique is used to calibrate the key model parameters and simulations are carried out for 2015,a year when field data was available.Our simulation results show that DMS seawater concentration ranges from 1.56 to 5.88 nmol L^(−1) with a mean value of 2.76 nmol L^(−1).DMS sea-air flux ranges from 2.66 to 5.00mmol m^(−2) d^(−1) with mean of 3.80mmol m^(−2) d^(−1).Positive correlations of about 0.5 between CHL and AOD were found in the study region,with higher correlations along the coasts of Jiangsu and Zhejiang Provinces.The elevated CHL concentration along the west coast is correlated with increased sea-water concentrations of DMS in the region.Our results suggest a possible influ-ence of DMS-derived aerosol in the local ECMS atmosphere,especially along the western coastline of ECMS.

Spatial Distributions and Potential Sources of Long Chain(C_(30),C_(32)1,15-)Alkyl Diols in Surface Sediments from Eastern China Marginal Seas

Long chain alkyl diols have shown important potential for the reconstruction of sea surface temperature,productivities and upwelling conditions in marine or lacustrine environments.However,little is known about the distribution and sources of the diols in eastern China marginal seas(CMS),which are areas of important organic carbon sink.Here the contents of C_(30) and C_(32)1,15-diols were analyzed in 181 surface sediments from eastern CMS.The similar distribution pattern and strong linear correlation between C_(30) and C_(32) diols indicated that they had similar biological source,with a dominance of C_(30) diol.Their contents ranged from 7-2726 ng g^(-1) for C_(30) diol and 5-669 ng g^(-1) for C_(32) diol,and both showed higher values mainly in the mud area of the Yellow Sea,while the TOC normalized contents showed a more obvious seaward increasing trend.The similar distribution pattern and significant positive correlation between diols and the other marine biomarkers(brassicasterol,dinosterol,C_(37) alkenones) indicated C_(30) and C_(32) diols in eastern CMS were mainly from marine algae.This conclusion was also supported by principal component analysis(PCA).Our results also showed that sediment diol contents were generally related to marine productivity,suggesting that diols could be applied for marine productivity reconstruction in eastern CMS.

Comparisons of surface Chl a and primary productivity along three transects of the southern South China Sea, northern Java Sea and eastern Indian Ocean in April 2011

Results are presented about the changes in chlorophyll a density, carbon fixation and nutrient levels in the surfacewaters of three transects of the southern South China Sea （SCS）, northern Java Sea （JS） and eastern Indian Ocean （IO） duringApril 5-16 of 2011. The in situ Chl a concentration and carbon fixation showed decreasing trends from high to low latitudealong the three transects, while the photosynthetic rate of phytoplankton estimated from 14C incorporation displayed no simplevariation with latitude. Chl a concentration and carbon fixation in the IO water was lower than that in the JS water. Highersalinity and lower contents of dissolved inorganic nitrogen （DIN） and silicate （SiO3^2-） characterized the IO water as comparedto the SCS or JS water, and the PO4^3- content was lower in the IO water than in the SCS or JS water in most cases. Our resultsalso indicate the importance of DIN and SiO3^2- concentrations for the geographical changes in phytoplankton biomass andprimary productivity among the three regions.

南海东部底水油藏水平井控水完井技术研究进展

南海东部底水油藏分布广泛,水平井开发方式可大幅度降低底水锥进速度,但由于水平段距离长,储层非均质性和水平井跟趾效应造成的点状见水易导致油井含水率大幅上升,降低生产效益。针对上述问题,南海东部油田采用ICD、AICD、C-AICD等控水工具,结合控水颗粒充填、智能分段分流等控水工艺,开展了底水油藏水平井控水完井技术研究与应用,取得显著效果。围绕南海东部底水油藏水平井控水完井技术研究进展,综合分析了不同控水方式的控水原理、技术特点和不同控水完井工具的特性曲线数学模型,总结了不同生产预测技术的应用规模和不同控水完井技术的应用效果。在此基础上提出了底水油藏水平井控水完井技术挑战和发展趋势,可为南海东部底水油藏水平井控水完井的进一步发展提供参考。

中国东部海区重点盆地演化与中深层油气资源潜力

石油和天然气资源的短缺已经严重制约了中国国民经济的发展,开拓油气勘探新领域和寻找后备油气基地已经上升为国家战略。以近些年海洋区域调查实测资料为基础,结合前人研究成果,对中国东部海域重点盆地构造特征和演化过程进行研究,分析各盆地油气成藏要素和成藏条件,并指出有利勘探区域。研究表明:按照盆地发育位置和成因,中国东部海域沉积盆地可划分为2种类型;受块体之间相互作用的控制,各盆地经历了不同的构造演化历史,发育明显不同的构造和地层特征,进而导致油气成藏要素和成藏模式截然不同;渤海湾盆地油气资源主要赋存于古近系中上部、新近系下部和前新生界潜山,北黄海盆地勘探重点是东部坳陷中生界,南黄海盆地应以中—古生界海相油气勘探为重点,东海陆架盆地则应兼顾中生界和新生界油气勘探。研究结果可以为中国东部海域沉积盆地油气勘探提供一定的参考。

地层压力预测技术在南海东部高温高压井中的应用

近几年南海东部钻探高温高压井数逐渐增多,严重影响安全钻井和资料录取。文章介绍了惠州某构造A1探井因钻遇超压地层而提前完钻及高压成因分析,重新部署A2,开展钻前地层压力精细预测分析,预测目的层压力系数在1.500~1.600之间,指导A2井成功钻井,MDT实测压力系数为1.595,实现勘探目的。

南海东部E油田钙质夹层特征及影响

钙质夹层研究对储层精细研究具有重要意义。通过动静态资料分析,对南海东部E油田钙质夹层岩性、测井、分布特征及其对油田动态的影响开展了研究。结果表明,E油田分为三类钙质夹层:生物碎屑灰岩、含生屑砂岩、钙质砂岩,夹层厚度在0.2~1.5m之间,小于0.5m厚钙质夹层测井特征不明显;单砂体间钙质夹层平面展布在100m以上,且发育较连续;单砂体内部厚度小于0.5m钙质夹层平面展布范围小于100m;利用垂向0.2m网格建立地质模型,模型更符合动态特征。

双碳背景下中国海油三个万亿大气区勘探战略思考

天然气具有清洁低碳等优势,在实现中国碳达峰、碳中和目标过程中将发挥重要作用。中国海油为响应国内不断加大天然气勘探开发力度的号召,提出了三个万亿大气区战略布局,即:南海万亿大气区、渤海万亿大气区和陆上鄂东-沁水万亿大气区,这三个万亿大气区是中国海油国内天然气增储上产的主要区域。本文聚焦资源基础、勘探方向、勘探理论认识与技术攻关方向,明确了中国海油建设三个万亿大气区的时间表和路线图。研究认为:①中国海油在南海北部、渤海海域和陆上探区具备实现三个万亿大气区的现实储量基础和资源潜力;②深水深层、深水超浅层、浅水深层和陆上深煤层,是未来中国海油开展天然气勘探的重要方向;③深部优质储层分布规律和深部油气富集机理等理论认识,深部储层改造、深部地震成像等关键技术,是未来需要重点攻关的理论技术方向。