大洋海区海-气CO_2通量单参数遥感算法的适用性检验

利用卫星遥感技术的优势,基于LDEO数据库的全球海表二氧化碳分压（PCO2）及海表温度（SST）等实测数据,初步建立东太平洋海区PCO2与SST的单参数经验算法,并采用相同区域的独立实测数据检验.结果表明,单参数算法在寡营养大洋海区具有良好的适用性,反演值与实测值之间的均方根误差（RMS）为0.51 Pa（1 Pa=9.869μatm）,由此估算出2003年6月该海域CO2通量为-1.4 mmol/（m2.d）,与实测估算的碳通量基本相符,能够很好地反映出海区CO2源汇特征.将该遥感算法运用到西大西洋海域（15°~25°N,60°~75°W）,反演值与实测值之间均方根误差（RMS）为0.69 Pa.检验结果表明,在寡营养大洋海区,单参数遥感算法具有一定的适用性,在受相似因子调控的同纬度海区可以使用同一遥感算法.     

基于WOA18的西北太平洋第一、二岛链间声速特征分析

本文基于WOA18温盐剖面数据集,利用声速经验公式计算了西北太平洋第一、二岛链间海区的声速剖面,研究了声速特征信息的诊断方法。通过提取声跃层、声道轴等声速特征信息,分别对表面声速、声跃层、声道轴进行分析,统计表面声速、声跃层和声道轴在各个季节的分布情况,得到了研究海区不同声学要素的季节变化特征。结果表明,表面声速主要在1 520～1 540 m/s区间变化,等值线基本与纬线平行,呈现出自低纬向高纬递减的趋势,声速值随季节变化较大;声跃层平均位置在低纬海区和高纬海区的差异较大,大约在100～650 m区域,低纬海区的声跃层受季节变化影响小,高纬海区的声跃层受季节变化影响大;声道轴深度基本在800m以深区域,总体上呈现南北深、中间浅的分布态势且四季变化幅度较小。     

基于遥感数据和表层声速的全海深声速剖面反演

海洋声速剖面严重影响着水下声传播特性,近实时地获取声速剖面对水下声通信、水下定位、鱼群探测等都有重要意义。单经验正交函数回归（single Empirical Orthogonal Function regression,sEOF-r）方法通过建立声速剖面的经验正交系数与海面遥感数据之间的线性回归关系来反演声速剖面。但是,海洋是一个复杂的动力系统,声速与海面遥感数据并不是简单的线性关系,因此,本文基于Argo历史网格数据,通过自组织映射（Self-Organizing Map,SOM）生成海平面高度异常（Sea Level Anomaly,SLA）、海表面温度（Sea Surface Temperature,SST）等海表遥感数据以及表层声速仪测量的表层声速与声速剖面异常之间的非线性映射;然后利用近实时的海表遥感数据和表层声速反演三维海洋声速场。声速剖面反演的结果表明,在多源信息融合的优势下,本文方法的反演性能最稳定且精度最高,声速剖面的平均反演精度比经典sEOF-r方法提高约2 m/s,比未考虑表层声速的经典SOM方法提高约1 m/s。     

利用Argo 浮标资料研究西北太平洋三维声速分布特征

利用西北太平洋海区2002～2009年的Argo浮标剖面温度、盐度资料构建成0.5°×0.5°水平分辨率的三维声速网格化资料,并据此分析该海区声速的空间分布及季节变化特征。研究表明：该海区10 m层等声速线分布的季节变化较为明显,春、冬季的等声速线几乎与纬线平行,黑潮流经区域等声速线呈现一定的弯曲。100 m层等声速线分布的季节变化较小：北赤道流区,等声速线从外海向近岸延伸;吕宋岛东南部沿海,等声速线向南弯曲;吕宋岛、台湾岛东部等声速线呈现偏北方向的弯曲;琉球群岛附近,等声速线朝北偏东方向弯曲。此外,研究海区存在深海声道,声道轴最深的区域主要在吕宋海峡和日本东南部海区,其中吕宋海峡处的声道轴有显著的季节变化特征。可见,利用Argo浮标资料可以初步得到西北太平洋声速的空间分布及其季节变化特征,随着Argo剖面资料的增多,对该海区的声速场认识将会愈加清晰。     

CNSVPGets软件获取声速剖面精度分析

提出最大差、中误差和全程平均差作为声速剖面曲线比较的精度指标。使用CNSVPGets软件对218条实测声速剖面曲线与软件获取剖面曲线进行对比计算,统计了比对曲线的最大水深、最大差、中误差、全程平均差;全部对比曲线的平均水深为1231.36m,平均最大差为6.74m/s,平均中误差为2.68m/s,全程平均差为1.72m/s。全程平均差小于5m/s的对比剖面对占95.4%,由此推论软件获取声速剖面的全程平均差极限误差为5m/s,中误差为2.5m/s;用软件获取声速剖面取代实测剖面用于水深测量计算,对测深精度的影响比海道测量规定的深度测量极限误差低1个数量级,因此可以使用软件获取声速剖面用于海道测量的深度测量声速改正。基于软件获取声速剖面的效率和重要性提出了建立和维护中国的全球声速剖面模型的建议。     

联合WOA2018温盐模型及实测温盐资料重构全深度声速剖面(二):精度评估

利用西太平洋海域多个站位的XBT、XCTD及CTD实测温盐资料,对WOA2018温盐模型的可靠性进行了评估,开展了全深度声速剖面重构试验。结果表明,当水深分别为761～1 100 m、大于1 101 m和大于1 821 m时,实测资料计算的声速剖面与温盐模型推算的声速剖面互差在-2.0～2.0 m/s、-0.7～0.7 m/s和-0.7～0.45 m/s,而与实测温度和盐度模型推算的声速剖面互差总体上在-0.2～0.2 m/s。基于临界探测深度处温盐实测值对探测深度以外温盐模型施加约束和控制,以提高声速预测值精度有待进一步研究。     

基于分层EOF的深海声速剖面时变特征建模

针对目前局部海域小时间尺度声速场建模方法未顾及不同深度区间内声速变化规律的问题,本文根据实测深海声速剖面的统计特征,提出了声速剖面分层方法,并进一步基于经验正交函数（Empirical Orthogonal Function, EOF）提出了局部小时间尺度的声速剖面分层时变模型构建方法。利用南海实测全海深声速剖面数据,分析了分层EOF第一模态系数和等效平均声速的日变化特征,并比较了不同拟合模型的精度。最后,利用试验海区的温度和潮汐数据分析了声速剖面周期变化的影响因素。结果表明： ①声速剖面分层EOF第一模态系数及等效平均声速具有日周期变化特征,上层声速日周期变化特征不明显,中层声速日周期变化特征较明显,下层声速变化较小但仍具有日周期变化特征;②局部海域小时间尺度声速拟合应考虑长期变化项的影响;③试验海区声速剖面EOF第一模态系数变化与温度显著相关,提取的声速剖面时变特征与海区潮汐周期特征基本吻合。     

用定深爆炸声源反演海底声学参数

根据2014年在南中国海开展声学试验的定深爆炸宽带声信号数据进行海底地声参数反演.考虑到不同海底声参数对不同声场物理参数的敏感程度不同以及不同海底声参数对不同反演方法的敏感程度亦不同,综合应用2种反演方法得到不同底质声参数:(1)根据接收的直达波和海底反射波计算得到关注海域的海底反射系数进而反演得到海底声阻抗;(2)实验海区的海底地形为大陆坡,选取Hamilton总结的关于沉积物声速与沉积物密度关系的经验公式,结合沉积物声阻抗与沉积物声速、沉积物密度的关系,进而反演得到沉积物声速和沉积物密度.沉积物声学参数的取样测量是在实验室条件下进行的,温度为23℃,大气压1×105Pa,由于沉积物孔隙海水是决定沉积物声速的关键且受温度压强变化的影响显著,本研究利用沉积物声速与孔隙海水声速的比值即使在温度压强变化的情况下较稳定的特点,可对沉积物声速在实验室条件和海底原位条件进行校正.校正到海底温度和压强后,反演结果与沉积物取样的实测结果和Hamilton总结的结果吻合得相当好:(1)声阻抗的反演结果为2.065 6×10~5g/(cm2·s),修正后的沉积物取样结果则为2.046 0×10~5g/(cm~2·s),Hamilton总结的结果为2.238 0×10~5g/(cm~2·s);(2)声速的反演结果为1 482.6m/s,修正后的沉积物取样结果为1 467.5 m/s,Hamilton总结的结果为1 502.8 m/s;(3)密度的反演结果为1.393 2 g/cm3,沉积物取样结果为1.400 0 g/cm~3,Hamilton总结的结果为1.489 0 g/cm3.     

基于字典学习的声速剖面重构和反演

声速剖面（Sound Speed Profile,SSP） 是海洋环境观测的重要要素之一,引入遥感参数进行SSP 反演可以实时获取声速数据。反演首先需要依托精确的基函数对声速场进行降维表示,本文提出一种利用非线性基函数-学习字典（Learned Dictionaries,LDs） 提高降维精度的方案,并使用在多源信息融合上表现良好的自组织竞争型神经网络算法（Self-organizing Map,SOM） 对南海海域进行SSP 反演。实验结果使用均方根误差（Root Mean Square Error,RMSE）作为精度评估。实验结果显示：LDs 较传统基函数-经验正交函数（Empirical Orthogonal Functions,EOFs） 的降维精度在使用三阶基函数时提升0.13 m/s,五阶基函数提升0.07 m/s。使用五阶基函数进行反演,LDs 的反演精度为3.01 m/s,低于EOFs 的反演精度2.47 m/s。其原因为反演误差在机器学习训练基函数时被放大,导致所求得反演系数欠优。LDs 基函数较之传统的EOFs 能够有效突破正交性的限制,更精确地表示声速的扰动,达到了更高的降维精度,为声学信号处理任务的基函数学习提供一种方案。     

基于ROMS模式的南海SST与SSH四维变分同化研究

卫星遥感观测获得了大量高分辨率的海面实时信息,包括海面温度（SST）和海面高度（SSH）等,同化进入数值模式可有效提升模拟精度。本文基于ROMS模式与四维变分同化方法（4DVAR）,使用AVHRR SST和AVISO SSH数据,开展了南海区域同化实验。为检验同化的效果,分别利用HYCOM再分析资料和Argo温盐实测数据分析了同化结果的海面高度、流场及温盐剖面的精度。对比结果表明,SST和SSH的同化能够改善ROMS的模拟结果:同化后海面高度场能够更为准确地捕捉海洋的中尺度特征,与HYCOM海面高度再分析资料相比,平均绝对偏差和均方根误差分别为0.054 m和0.066 m;与HYCOM 10 m层流场相比,东向与北向流速平均绝对偏差分别为0.12 m/s和0.11 m/s,相比未同化均提升约0.01 m/s;温盐同化结果与Argo温盐实测具有较高的一致性,温度和盐度平均绝对偏差为0.45℃、0.077,均方根误差为0.91℃、0.11,单个的温盐廓线对比说明,同化结果与HYCOM再分析资料精度相当。     

白云凹陷北坡珠江组下段陆架边缘三角洲特征及其主控因素

为了明确白云凹陷北坡珠江组下段陆架边缘三角洲的形成演化阶段及其主要控制因素,采用地震沉积学、层序地层学的相关理论和方法,结合钻测井数据、地震反射结构特征和均方根振幅属性等资料,在前人研究的基础上对该陆架边缘三角洲的识别特征、演化模式和控制因素进行了重新认识和探讨分析。结果表明:陆架边缘三角洲在顺物源方向具有高角度斜交型前积反射,缺乏顶积层的海岸平原相,其前端发育盆底扇沉积;垂向沉积序列以多期反旋回的前三角洲、席状砂、河口沙坝和水下分流河道的叠置为特征,发育陆坡区常见的生物扰动、泥质条带变形和滑塌、滑动现象;珠江组下段陆架边缘三角洲形成于强制海退体系域时期,并伴随着盆底扇的发育,而低位体系域时期主要发育斜坡扇和低位楔状体;构造活动促使白云凹陷北坡在珠江组下段时期形成稳定分布的陆架坡折带,珠江组下段时期古珠江携带的充沛物源和该时期强烈的海平面下降使碎屑沉积物能够进积至陆架边缘,甚至陆坡地区形成陆架边缘三角洲沉积。     

Tracing dissolved organic matter cycling in the eastern boundary of the temperate North Atlantic using absorption and fluorescence spectroscopy

Apparent oxygen utilization (AOU), dissolved organic carbon (DOC), coloured dissolved organic matter (CDOM) absorption spectra, and CDOM fluorescence characteristic of aromatic amino acids (excitation/emission 280 nm/320 nm; F(280/320)) and marine-humic like substances (320 nm/410 nm; F(320/410)) were measured in full depth during a cruise in the temperate Eastern North Atlantic (ENA). An optimum multi-parameter (OMP) inverse method was run to calculate water mass proportion-weighted average (archetypal) concentrations of these chemical parameters for all water masses and samples. Archetypal concentrations retain the variability due to water mass mixing and basin scale mineralization from the water mass formation sites to the study area. Conversely, the difference between measured and archetypal concentrations, retain the variability due to dissimilarities in mineralization processes within the study area. Our analysis indicates that DOC supported 26±3% of the AOU in the dark temperate ENA and that basin scale processes occurring at and from the formation area of the water masses explained 63% of the total DOC variability. Our data also suggests that DOC remineralized at the basin scale was of lower molecular weight, and with a lower proportion of fluorescent aromatic amino acids than found within the study area. The relationship between the absorption coefficient at 254 nm (a_CDOM(254)) and AOU indicates that a_CDOM(254) was consumed during organic matter remineralization in the dark ocean, with 55% of the variability being explained by basin scale processes. The relationships of F(320/410) with AOU and DOC confirmed that marine humic-like substances are produced by microbial degradation processes, at a rate of 6.1±0.9×10⁻³ mg equivalents of QS mol AOU⁻¹. Our results also indicate that basin-scale remineralization processes account for 85% of the total variability of F(320/410), emphasizing that large scale processes control the formation of humic-like substance in the dark ENA.     

Perceptions and preferences of commercial fishers for dedicated access privilege framework in a multispecies fishery

The decline of the world's fisheries and the inability of traditional management frameworks to maintain them, has led managers to adopt alternative management frameworks. The use of dedicated access privileges have often been shown to have varying popularity among factions within the commercial fishing industry and managers. Here, we examine commercial fishers' preference for alternative management frameworks in the context of a unique multispecies fisheries of the Florida Keys. By surveying commercial fishers, we find that that the size of operation plays no role in affecting fisher perception regarding dedicated access privileges. Furthermore, fishers who are organized are less likely to support dedicated access privilege frameworks. Overall, we do not find enough support in the fishing industry for the implementation of dedicated access privileges in the Florida Keys. These findings can provide inputs in developing effective management plans in the region.     

南海名浅考

根据历史文献分析,已知南海海名最早出现于周宣王（827BC--782BC在位）时的《江汉》诗中。秦汉之间214BC—111BC时著的《山海经·海内东经》篇,记述了现时广东省三水和广州以南地区当时为海,称南海。这可从《史记》和《汉书》的记述,以及现代珠江三角洲的考古学、第四纪地质学和河口演变的研究成果所证实。南海古时别名涨海,明清时期外国人称为大明海和大清海。清朝以来,外国人把它翻译成（或称作）英文“South China Sea”,而近代某些中国人再把这个英文名词直译成汉文“南中国海”,忽视“南海”固有的中文名称。民国和中华人民共和国政府先后出版的地图和其他正式出版物,皆只用“南海”名。     

一株分离于湘江污染水域的酵母(Candida fermentati)的鉴定及其Cd~(2+)的吸附特性

对湘江湘潭段周边污染水域的微生物群落结构进行调查,筛选出一株能够耐受较高浓度镉的野生型酵母样真菌,命名为XTWJX菌株,并对其进行形态学特征、生理试验以及ITS序列和26S rDNA D1/D2区序列分析。结果表明,该菌株属于假丝酵母属的发酵假丝酵母Candida fermentati。金属抗性试验表明,XTWJX菌株对测试的9种不同金属离子显示出较高的抗性能力,尤其是对毒性较大的Cd2+的抗性能力高达6mmol/L,暗示该菌株可能具有应用前景。研究了XTWJX菌株对Cd2+的吸附特性,结果表明,在Cd2+浓度为10mg/L的水溶液中,该菌株对Cd2+显示出有较强的吸附能力。这一结果暗示XTWJX菌株的分离很可能为Cd2+污染的河流和湖泊等水生环境的生物修复提供了一种新型的生物材料。     

基于CMIP5模拟预估21世纪珠江三角洲地区由于海平面上升而导致的淹没区面积

Projections of potential submerged area due to sea level rise are helpful for improving understanding of the influence of ongoing global warming on coastal areas. The Ensemble Empirical Mode Decomposition method is used to adaptively decompose the sea level time series in order to extract the secular trend component. Then the linear relationship between the global mean sea level(GMSL) change and the Zhujiang(Pearl) River Delta(PRD)sea level change is calculated: an increase of 1.0 m in the GMSL corresponds to a 1.3 m(uncertainty interval from1.25 to 1.46 m) increase in the PRD. Based on this relationship and the GMSL rise projected by the Coupled Model Intercomparison Project Phase 5 under three greenhouse gas emission scenarios(representative concentration pathways, or RCPs, from low to high emission scenarios RCP2.6, RCP4.5, and RCP8.5), the PRD sea level is calculated and projected for the period 2006–2100. By around the year 2050, the PRD sea level will rise 0.29(0.21 to 0.40) m under RCP2.6, 0.31(0.22 to 0.42) m under RCP4.5, and 0.34(0.25 to 0.46) m under RCP8.5, respectively.By 2100, it will rise 0.59(0.36 to 0.88) m, 0.71(0.47 to 1.02) m, and 1.0(0.68 to 1.41) m, respectively. In addition,considering the extreme value of relative sea level due to land subsidence(i.e., 0.20 m) and that obtained from intermonthly variability(i.e., 0.33 m), the PRD sea level will rise 1.94 m by the year 2100 under the RCP8.5scenario with the upper uncertainty level(i.e., 1.41 m). Accordingly, the potential submerged area is 8.57×103 km2 for the PRD, about 1.3 times its present area.     

Experimental and numerical study on vortex-induced motions of a deep-draft semi-submersible

An experimental study on vortex-induced motions (VIM) of a deep-draft semi-submersible (DDS) was carried out in a towing tank, with the aim to investigate the VIM effects on the overall hydrodynamics of the structure. In order to study the fluid physics associated with VIM of the DDS, a comprehensive numerical simulation was conducted to examine the characteristics of vortex shedding processes and their interactions due to multiple cylindrical columns. The experimental measurements were obtained for horizontal plane motions including transverse, in-line and yaw motions as well as drag and lift forces on the structure. Spectral analysis was further carried out based on the recorded force time history. These data were subsequently used to validate the numerical model. Detailed numerical results on the vortex flow characteristics revealed that during the “lock-in”, the vortex shedding processes of the upstream columns enhance the vortex shedding processes of the downstream columns leading to the rapid increase of the magnitude of VIM. In addition to the experimental measurements, for the two uniform flow incidences (0° and 45°) investigated, comprehensive numerical data of the parametric study on the VIM characteristics at a wide range of current strength will also serve as quality benchmarks for future study and provide guidance for practical design.     

Investigation and comparison of one-dimensional (1-D) analytical models prediction for salt intrusion condition in two selected estuaries

Abstract

In this paper, two analytical models used worldwide to assess salinity variation in alluvial estuaries are applied to the Ashtamudi estuary, a Ramsar site, southwest coast of India; and Bouregreg estuary, in northwest part of Morocco. The estuaries’ bathymetry is described by an exponential function. Both models are quite similar and use a predictive equation for the dispersion in the estuary mouth (D₀). The major difference between the two models is the use of the constant value of K?=?0.5 for the Van der Burgh coefficient (K) and the introduction of the correction factor ζ, which is a function of damping (δ) and shape (γ). The performance of these two models was evaluated by comparing their results with field measurements; this revealed that both analytical models apply well to both the estimation of salinity distribution and the prediction of salt intrusion in the Ashtamudi and Bouregreg estuaries (Ashtamudi: RMSE = 0.60–1.22 ppt; Bouregreg: RMSE = 0.92–2.71 ppt). One model agrees more with the field measurements of salinity distribution along the estuaries axis; the second underestimate and overestimate some values of salinity distribution along the estuaries. Possibly, the constant value of K?=?0.5 for the Van der Burgh coefficient (K) has applicability limits for the estuaries under tidal conditions. The specifying of the parameterization may be a field of research.     

基于无人机紫外与SAR的溢油遥感监测方法研究

溢油污染不仅会造成巨大的经济损失,而且给生态环境带来难以修复的破坏。准确、高效地监测海面溢油仍是当前亟需解决的问题。紫外传感器对油膜非常敏感,可快速发现,但存在误判;而SAR(SyntheticApertureRadar)溢油探测的精度较高,两者相结合可准确探测溢油。无人机平台可低成本地实现溢油快速应急响应,无人机载SAR和紫外传感器的载荷重量小,可同时集成于无人机上开展联合溢油探测,以满足业务化监测需求,此方面的研究尚未见有相关报道。本文拟研究溢油不同种类、厚度、在不同海洋环境条件下的紫外图像特征和SAR纹理特征、形状特征、散射特征,构建溢油特征数据库,并建立一种基于特征组合的溢油SAR与紫外联合探测方法;在此基础上研究对无人机数据获取模式和控制单元等的改造方案,进而实现溢油SAR和紫外图像的高效获取。     

Hydrodynamic shape optimization by high fidelity CFD solver and Gaussian process based response surface method

A computational framework for hydrodynamic shape optimization of complex ship hull form is proposed and applied to improve the calm water performance of the KRISO Container Ship (KCS). The framework relies on three key features: a novel shape morphing method based on a combination of subdivision surfaces and free form deformations, a robust three dimensional viscous computational fluid dynamic solver based on the openFOAM open-source libraries and a Gaussian process-response surface method (GP-RSM) based on ordinary Kriging model which has been created to speed-up the evaluation of the quantity of interest (QoI) of the design process.The accuracy of the hydrodynamic solver is proven by comparing the obtained results against available experimental measurements. A preliminary sensitivity analysis on the mesh size has been carried out aiming at reducing the computational burden required by the CFD predictions. Three GP-RSMs have been trained relying on increasing number of hull designs. Each surrogate model has been cross-validated by both leave-one-out and k-fold techniques. The behaviours of these multi-dimensional surfaces have been analyzed in details by sampling the investigated design space with 10⁷ points according to a Full-Factorial algorithm, highlighting the regions of maximum deviation with respect to the resistance of the reference hull. The three optimum designs provided by the corresponding GP-RSM models have been verified by using high-fidelity CFD simulations with a refined mesh configuration. Calm water resistance, wave patterns and pressure distributions over the selected hull surfaces have been discussed in the light of the generated shape variations.