Relationship between the Guinea Current and the Coastal Upwelling in Northern of Gulf of Guinea

The variability of ocean circulation and sea surface temperature (SST) in the tropical Atlantic, especially in the Gulf of Guinea (GG), defines this region as exceptionally rich from an oceanographic perspective. The Guinea Current (GC), as the major surface current, plays a significant role in marine productivity and coastal upwelling in the GG. This coastal upwelling is known to influence the climate of the surrounding region, primary productivity and local fisheries. Studies on GC variability and its impact on this coastal upwelling have highlighted that the upwelling downstream of Cape Palmas is influenced by GC detachment, topographic variations and advective processes leading to significant vertical mixing. This study aims to analyze the interannual variability of the GC and its impact on coastal upwelling using the Coastal and Regional Ocean COmmunity model (CROCO). The model’s evaluation is conducted using observational data, specifically Geostrophic and EKman Current Observatory (GEKCO) and Ocean Surface Current Analysis (OSCAR) for currents, and Air-sea Fluxes for the global Tropic ocean-description (TROPFLUX) and Optimum Interpolation-Sea Surface Temperature (OI-SST) for temperature. Thus, the model evaluation indicates that it accurately replicates ocean circulation and SST patterns in the tropical Atlantic and the GG. The joint analysis of upwelling indices (surface and intensity) and the position of the GC core allowed us to conclude that the displacement of the GC core does indeed influence the upwelling indices in the northern part of GG. However, other oceanic and atmospheric mechanisms such as vertical diffusion and horizontal advection as proposed by previous studies may also affect the year-by-year variability of coastal upwelling in the northern GG.

Hydrodynamic Simulation of the Pagasitikos Gulf, Greece

Semi-enclosed sea basins have difficulty in recharging their waters due to limited communication with larger water bodies, with understandable consequences for their environmental status. This paper aims at the computational simulation of the hydrodynamic characteristics of the waters of the Pagasitikos Gulf (Greece), which has limited communication and water exchange with the Aegean Sea and is subject to intense environmental pressures The Estuary, Lake & Coastal Ocean 3d hydrodynamic Model (ELCOM 2.2) combined with its later version Aquatic Ecosystem Model-3d (AEM3D) were used for the simulation. The simulation included the topography of the area, the bay’s bottom geometry, atmospheric loadings, tides, the influence of the Coriolis force and boundary conditions. The hydrodynamic behaviour of the bay, water circulation, velocities at the surface and in depth, water recharge and residence time throughout the bay, density variation and other factors were examined to determine the impact of all these on the aquatic ecosystem.

Effects of Neo-Tethyan evolution on the petroleum system of Persian Gulf Superbasin

Considering the Neo-Tethyan tectonic process and the resulting environmental changes,a geodynamic model of“one-way train loading”is proposed to analyze the formation and evolution mechanism of the Persian Gulf Superbasin with the most abundant hydrocarbons in the world.The Persian Gulf Superbasin has long been in a passive continental margin setting since the Late Paleozoic in the process of unidirectional subduction,forming a superior regional space of hydrocarbon accu-mulation.During the Jurassic-Cretaceous,the Persian Gulf Superbasin drifted slowly at low latitudes,and developed multiple superimposed source-reservoir-caprock assemblages as a combined result of several global geological events such as the Hadley Cell,the Equatorial Upwelling Current,and the Jurassic True Polar Wander.The collision during the evolution of the foreland basin since the Cenozoic led to weak destruction,which was conducive to the preservation of oil and gas.Accordingly,it is be-lieved that the slow drifting and long retention in favorable climate zone of the continent are the critical factors for hydrocarbon enrichment.Moreover,the prospects of hydrocarbon potential in other continents in the Neo-Tethyan were proposed.

Multi-scenario Simulation for 2060 and Driving Factors of the Eco-spatial Carbon Sink in the Beibu Gulf Urban Agglomeration, China

Since China announced its goal of becoming carbon-neutral by 2060, carbon neutrality has become a major target in the development of China's urban agglomerations. This study applied the Future Land Use Simulation(FLUS) model to predict the land use pattern of the ecological space of the Beibu Gulf urban agglomeration, in 2060 under ecological priority, agricultural priority and urbanized priority scenarios. The Integrated Valuation of Ecosystem Services and Trade-offs(In VEST) model was employed to analyse the spatial changes in ecological space carbon storage in each scenario from 2020 to 2060. Then, this study used a Geographically Weighted Regression(GWR) model to determine the main driving factors that influence the changes in land carbon sinking capacity. The results of the study can be summarised as follows: firstly, the agricultural and ecological priority scenarios will achieve balanced urban expansion and environmental protection of resources in an ecological space. The urbanized priority scenario will reduce the carbon sinking capacity. Among the simulation scenarios for 2060, carbon storage in the urbanized priority scenario will decrease by 112.26 × 10^(6) t compared with that for 2020 and the average carbon density will decrease by 0.96 kg/m^(2) compared with that for 2020. Carbon storage in the agricultural priority scenario will increase by 84.11 × 10^(6) t, and the average carbon density will decrease by 0.72 kg/m^(2). Carbon storage in the ecological priority scenario will increase by 3.03 × 10^(6) t, and the average carbon density will increase by 0.03 kg/m^(2). Under the premise that the population of the town will increases continuously, the ecological priority development approach may be a wise choice.Secondly, slope, distance to river and elevation are the most important factors that influence the carbon sink pattern of the ecological space in the Beibu Gulf urban agglomeration, followed by GDP, population density, slope direction and distance to traffic infrastructure.At the same time, urban space expansion is the main cause of the changes of this natural factors. Thirdly, the decreasing trend of ecological space is difficult to reverse, so reasonable land use policy to curb the spatial expansion of cities need to be made.

Study on Wave Characteristics from the South Atlantic Ocean to the Gulf of Guinea Based on Short-Term Numerical Simulation in Winter Season

Waves play a major role in the ocean phenomena in the Gulf of Guinea(GoG). In order to reveal the spatial-temporal distribution characteristics and the propagation mechanism of waves from the South Atlantic Ocean to the GoG, 4typical points located in mid-latitude of South Atlantic(14°30′W, 30°0′S), south of the GoG(10°30′W, 15°0′S), offshore of the GoG(0°0′, 0°0′) and near shore of the GoG(6°4′58.8″W, 4°3′36″S) are selected, and waves from Atlantic Ocean to GoG are simulated by using a two-layer-nesting wave numerical model SWAN(Simulating Waves Nearshore). The results show that the hybrid waves(waves hereafter) and the swells have strong relationship with local wind in Roaring Forties and at mid-latitude of South Atlantic Ocean, while there is no obvious correlation between waves and local winds in the GoG. Swells are generated in the South Atlantic Ocean and propagate into the GoG. 2D wave spectra at the four selected typical points are simulated. The spectral pattern and wave component structure indicate that the wave system in GoG is dominated by the S-SW swells generated from Roaring Forties and mid-latitude of South Atlantic, whether it is at maximum(2.2-2.8 m), medium(1.8-2.2 m) or minimum(1.2 m) significant wave height in the GoG during simulation period.

Seasonal Variability of Biofouling Community Structure in the Gulf of Mannar,Southeast Coast of India:A Multivariate Approach

In this research,an Underwater Biofouling Panel(UWBFP)system was erected for the qualitative and quantitative estimation of macro fouling organisms in the Gulf of Mannar.Forty-four biofoulers were identified from four types of selected test panels.Among these biofoulers,Amphibalanus amphitrite(Darwin,1854)was the dominant one.The concrete panel encouraged the highest barnacle density compared to the other panels.Three series of test panels were used to assess the seasonal density of biofouling communities.The overall variation in barnacle count in the seaward and shoreward sides of all these three series were tested.They were found to be significantly different from each other.The greater variations in the barnacle density observed in this study in A-series of test panels could be due to the lack of or absence of other foulers to compete within the fortnight.The Shannon-Wiener species diversity index showed the highest diversity in wood substratum among the three series with greater accumulation of different types of fouling organisms.Multivariate analyses were also performed to understand the seasonal variation as well as the settlement pattern on the different directions of test panels based on validated data.PCA showed a strong variability(PC1 between 70.8%and 98.6%variance)between the directions of the panels in connection with barnacle density.The shade plot and CAP analysis segregated the short-term A-series test panels from the long-term(B-and C-series)test panels.Hence,the output was helpful in understanding the recruitment status of various faunal resources involved in the biofouling processes.

Chemical exposures and suspected impacton Gulf War Veterans

Gulf War Illness(GWI) encompass a spectrum of maladies specific to troops deployed during the Persian Gulf War(1990–1991). There are several hypothesized factors believed to contribute to GWI, including(but not limited to)exposures to chemical agents and a foreign environment(e.g., dust, pollens, insects, and microbes). Moreover, the inherent stress associated with deployment and combat has been associated with GWI. While the etiology of GWI remains uncertain, several studies have provided strong evidence that chemical exposures, especially neurotoxicants,may be underlying factors for the development of GWI. This mini style perspective article will focus on some of the major evidence linking chemical exposures to GWI development and persistence decades after exposure.

Forty-year investigation of wave power in energetic region of Persian Gulf in Iranian territorial waters by using short-term and new long-term stability assessment parameters

The wave power in high potential area of the northern Persian Gulf(near to Iranian coastal areas)is assessed by taking into account the temporal and spatial distributions of wave power for a period of forty years.For this purpose,assimilated wind data of European Centre for Medium-Range Weather Forecasting Interim Reanalysis(ERA-Interim),and hydrography data of General Bathymetric Chat of the oceans(GEBCO)are used as SWAN model.Seven locations are investigated in the study area by considering the amount of coefficient of variation,the amount of average annual power,and the short-term and a new long-term(decadal variability index)power stability assessment parameters.The results showed more stability in the eastern parts of the study area and concluded that a narrow line between the point which is in the middle and another point which is in the eastern middle part of the study area may be the best locations for more investigation and the feasibility study for energy converter farms.Also,it is found that the middle part of the study region with about 2.5 kW/m power is the most energetic area.It is concluded that the dominant direction of wave power distribution in all points is the northeast,and this dominant direction has not changed during the forty-year period.It is observed that the mean annual energy increases with a slight slope in the total 40 a,and this increasing trend is more obvious in the fourth decade.Although it is observed that the wave power of the second decade has the most stability and the least variation,the wave power in the fourth decade has the most variation.Moreover,the results showed that the study region’s wave power increase by approximately a mean change rate of 0.027 kW/(m·a);and the maximum change rate of wave power was in the northwest part and the minimum change rate of wave power was in the southeast part which were about 0.036 kW/(m·a)and 0.014 kW/(m·a),respectively.

Regional Intrusive Signature from the Cameroon Coastal Basins to Bioko Island in Equatorial Guinea (Gulf of Guinea) Using Gravity Studies

The Gulf of Guinea constitutes an area of great petroleum potential yet with very limited geophysical research information. Consequently in this study, a Bouguer anomaly map has been computed from gravity data covering regions stretching from the Cameroon coastal basins to Bioko island (formerly Fernando Po) which is part of Equatorial Guinea. The data were further processed for Source Edge Detection (SED), Euler 3D deconvolution, 3D surface oriented models and 3D voxel solutions. The results confirmed the presence of previously identified intrusive bodies around the Douala and Kribi/Campo sedimentary sub-basins and went ahead to suggest a probable continuity between these two. A possible extension of this body offshore the Gulf of Guinea right up to Bioko island with very striking similarities was also highlighted and it shows characteristic variations in the depth to the surface of the body at different locations.

Gravity anomalies determined from mean sea surface model data over the Gulf of Mexico

With the improvements in the density and quality of satellite altimetry data,a high-precision and high-resolution mean sea surface model containing abundant information regarding a marine gravity field can be calculated from long-time series multi-satellite altimeter data.Therefore,in this study,a method was proposed for determining marine gravity anomalies from a mean sea surface model.Taking the Gulf of Mexico(15°–32°N,80°–100°W)as the study area and using a removal-recovery method,the residual gridded deflections of the vertical(DOVs)are calculated by combining the mean sea surface,mean dynamic topography,and XGM2019e_2159 geoid,and then using the inverse Vening-Meinesz method to determine the residual marine gravity anomalies from the residual gridded DOVs.Finally,residual gravity anomalies are added to the XGM2019e_2159 gravity anomalies to derive marine gravity anomaly models.In this study,the marine gravity anomalies were estimated with mean sea surface models CNES_CLS15MSS,DTU21MSS,and SDUST2020MSS and the mean dynamic topography models CNES_CLS18MDT and DTU22MDT.The accuracy of the marine gravity anomalies derived by the mean sea surface model was assessed based on ship-borne gravity data.The results show that the difference between the gravity anomalies derived by DTU21MSS and CNES_CLS18MDT and those of the ship-borne gravity data is optimal.With an increase in the distance from the coast,the difference between the gravity anomalies derived by mean sea surface models and ship-borne gravity data gradually decreases.The accuracy of the difference between the gravity anomalies derived by mean sea surface models and those from ship-borne gravity data are optimal at a depth of 3–4 km.The accuracy of the gravity anomalies derived by the mean sea surface model is high.

The Impact of Climate Change on the Stratification of Coastal Areas of the Euboean Gulf and the Diffusion of Urban Wastewater in Them

Hydrodynamic circulation in a marine environment, characterized by the influence of strong tides, atmospheric loading and bathymetry, is a complex phenomenon. The physical and hydrodynamic characteristics of this flow are absolutely crucial for the vertical mixing of the sea masses and consequently for the mixing of their physico-chemical parameters, such as nutrients and oxygen, as well as for the diffusion and dispersion of passive pollutants, the recharge of the waters and the general environmental situation. This paper examines the effect of a future increase in mean air temperature on the water column stratification of coastal areas of interest, which are subject to the above loadings and receive treated urban wastewater, and how this increase could affect their diffusion and mixing of conservative pollutants contained therein.

The Hydrodynamic Behaviour of Euboean Gulf Coastal Areas and the Mixing of the Physico-Chemical Characteristics of Urban Sewage Discharged into Them under the Influence of Climate Change

The hydrodynamic circulation within the marine environment is a complex phenomenon, characterized by the interplay of strong tidal forces, atmospheric influences, and bathymetric features. The physical and hydrodynamic attributes of this flow play a pivotal role in promoting vertical mixing of seawater masses, thereby facilitating the integration of their physical and chemical parameters, including nutrients and oxygen. Additionally, they are instrumental in governing the dispersion and diffusion of pollutants originating from urban sewage, contributing to the overall water renewal process and environmental quality. This study investigates the potential impact of anticipated increases in average air temperatures on water column stratification in coastal regions susceptible to these dynamic influences. These areas receive treated urban sewage, and the study aims to assess how these temperature changes might influence the dispersion and mixing of pollutant loads present in these coastal waters.

A three-dimensional Moho depth model beneath the Yemeni highlands and rifted volcanic margins of the Red Sea and Gulf of Aden, Southwest Arabia

Knowing Moho discontinuity undulation is fundamental to understanding mechanisms of lithosphereasthenosphere interaction, extensional tectonism and crustal deformation in volcanic passive margins such as the study area, which is located in the southwestern corner of the Arabian Peninsula bounded by the Red Sea and the Gulf of Aden. In this work, a 3D Moho depth model of the study area is constructed for the first time by inverting gravity data from the Earth Gravitational Model(EGM2008) using the ParkerOldenburg algorithm. This model indicates the shallow zone is situated at depths of 20 km to 24 km beneath coastal plains, whereas the deep zone is located below the plateau at depths of 30 km to 35 km and its deepest part coincides mainly with the Dhamar-Rada ’a Quaternary volcanic field. The results also indicate two channels of hot magmatic materials joining both the Sana’a-Amran Quaternary volcanic field and the Late Miocene Jabal An Nar volcanic area with the Dhamar-Rada’a volcanic field. This conclusion is supported by the widespread geothermal activity(of mantle origin) distributed along these channels,isotopic data, and the upper mantle low velocity zones indicated by earlier studies.

海湾局势变化与英国的撤离(1961-1968)

英国曾长期在海湾地区处于主导地位,其海湾政策的转变与其在海湾地区的主要利益密切相关。二战后,英国在海湾地区的主要利益转变为以石油为中心的经济利益。保护经济利益成为英国在海湾地区政治、军事存在的首要目标。60年代初期海湾地区的不稳定状态要求英国增强其政治、军事存在,但1963年后的海湾局势变化在很大程度上消除了海湾地区的不稳定因素,英国的海湾利益不再依赖其政治、军事力量提供保护。英军继续留在海湾不仅不能增进本国在该地区的经济利益,反而成为其政府的政治和财政负担。此外,国防支出紧缩、从亚丁撤军、阿拉伯民族主义等因素也不利于英国政治、军事力量继续留在海湾。经过多次成本—收益分析,英国政府最终决定撤出海湾。此举对海湾地区现代国家体系的建立和现代国际格局的形成具有重要影响。

文旅融合发展促进共同富裕的路径研究——以北部湾城市群为例

在共同富裕的重大政策指引下,国家对文旅产业的发展提出了更高要求,如何推动文旅产业融合高质量发展以体现其在共同富裕的重要价值是一项新的时代课题。北部湾地区城市群的文化底蕴深厚,旅游资源禀赋丰富,推进湾区文旅产业融合将对共同富裕具有重要的作用,同时也是城市文旅产业实现高质量发展的重大机遇。文章立足共同富裕的政策导向,选取了北部湾地区数个城市的文旅发展概况作为参考,在综合分析的基础上提出针对性的融合发展思路与建议,为推动湾区城市群文旅产业向高端化、现代化提质升级,实现高质量可持续发展,提升文旅产业融合发展的综合效应,发挥文旅产业在湾区建设的功能作用提供有益借鉴。

北部湾港平陆运河江海联运方案研究

平陆运河始于西江航运干线中上游的西津枢纽水库支流平塘江口,终于北部湾港,是优化提升全国水运网络、加快建设国家综合立体交通网的联网工程,是建设西部陆海新通道、加快建设交通强国的标志性工程。根据《国家综合立体交通网规划纲要》部署,北部湾港总体规划正在编制,需要统筹考虑平陆运河江海联运枢纽空间布局和平面布置方案。综合考虑平陆运河江海联运量、北部湾港各港区建港条件和资源容量,以及既有港口资源利用情况,按照“就近转运、用足存量”的原则,因地制宜提出分货类的江海联运枢纽布局,制定了大小泊位能力匹配、运输组织高效的平面布置方案,同时也提出明确防城港域航区划分、研究开通防城港水运疏港通道(皇城坳运河)、有序推进现状码头升级改造等建议,为平陆运河建设投产后江海联运平稳运行提供技术支撑。

基于绿色创新系统的北部湾城市群联动效应测度及驱动力研究

在区域协调发展的背景下,建立健全城市群联动发展机制是构建城市协调发展格局的必然要求。基于Vague集理论测度2006—2020年北部湾城市群联动效应,并利用Dagum基尼系数、地理探测器对其进行差异分析和驱动力分析。结果表明:①研究期内,北部湾城市群联动效应水平稳步增长,空间上呈现“广东>广西>海南”的分布格局;其中,绿色生态水平最高,经济发展增速最快,资源禀赋、基础设施、绿色创新3个维度与联动效应水平递增趋势相近;②从联动效应的区域差异来看,广东、广西、海南三地与北部湾城市群整体联动效应差异呈同向增长,且广东发展差异低于广西、海南;软环境对联动效应的驱动作用整体高于硬环境,科技带动力的驱动作用最高,资源驱动作用显著低于其他因素;北部湾城市群联动效应由多种驱动因素交互作用形成,双因子交互影响强度大于单因子驱动。

北部湾港大型深水航道远期适应性及通航标准仿真分析

以北部湾港北海港域30万吨级深水航道工程为背景,采用智能体仿真建模方法,建立北海港域铁山进港航道船舶进出港、锚泊、航行和码头停泊作业全过程仿真模型。通过仿真定量分析港口通过能力和航道服务水平等指标,结合航道平面尺度分析,提出湾外主航道远期推荐尺度和通航标准。基于港口通过能力瓶颈分析和支航道通航标准优化仿真分析,提出主要支航道北暮航道部分航段通航标准优化建议。结果表明,湾外主航道2035年达到(10+5)万t船双向通航,2050年进一步达到(10+10)万t船双向通航的推荐通航标准;北暮航道1段通航标准由15万t船舶单向通航优化为兼顾2万t船舶双向通航,对提升港口通过能力具有较好效果。

相对密实度和固结应力比对北部湾海砂动力特性影响的试验研究

北部湾地区拥有丰富的海洋资源,海洋工程在这一地区的发展日益重要,了解海砂在不同固结应力比和密实度条件下的动力特性,对于海岸线保护、港口建设、堤防工程等都至关重要。为探究北部湾海砂的动力特性,针对北部湾海砂开展了一系列的固结不排水循环动三轴试验,分析了相对密实度和固结应力比对北部湾海砂的轴向累积应变、动弹性模量、动孔压以及滞回曲线的影响。研究表明:在相同振次水平下,随着固结应力比和相对密实度的增大,海砂的轴向累积应变随之减小;动孔压随着固结应力比的增大线性减小,在低相对密实度(Dr≤50%)下,动孔压随振次的增大而增大,在高相对密实度(Dr=70%)下,动孔压随振次先增后减;动弹性模量随着振次的增加出现刚度软化现象,增大相对密实度与固结应力比,较明显地减缓了动弹性模量的衰减速率;随着固结应力比和相对密实度的增大,滞回曲线包围的面积减小,滞回曲线由不封闭曲线转为封闭曲线。这些研究成果可以为北部湾围填海工程提供一定的参考。

2023年6月一次北部湾低压极端暴雨过程天气气候特征

利用逐日再分析资料,对2023年6月7-10日北部湾低压持续性极端暴雨过程的天气气候特征进行研究。结果表明,(1)持续性极端暴雨前期和期间,副热带高压异常偏北偏西,位置稳定。孟加拉湾-南海-菲律宾一带热带辐合带活跃,南海西部有低压系统生成,并移入北部湾。(2)季节内振荡(MJO)处在第2、3位相,受其东传影响,中高纬度环流形成的槽脊位置有利冷空气南下影响广西。中层500 hPa我国东北地区附近有东北低涡维持,低涡后部强盛偏北风引导冷空气南下,受偏北偏西的副高阻挡,有小股冷空气渗透南下影响广西。(3)低层850 hPa印度洋越赤道气流和西南季风强盛但活动偏南,印度洋-中南半岛-南海的西南风急流受台风“古超”阻挡转向成南风,使气流在北部湾形成气旋性弯曲。广西西北部有弱东北风,增强北部湾周边气流的气旋性辐合。(4)广西南部和北部湾一带位于200 hPa东亚副热带高空急流右侧与850 hPa西南风低空急流左侧,高空辐散和低层辐合,1000~300 hPa水汽通量辐合区水汽条件充沛。中、低纬度天气系统的协同作用,为这次持续性极端暴雨提供有利的稳定大尺度环流背景,以及充分的热力、动力条件。