波高周期联合分布四种重现水平对比分析*

基于Gumbel-Hougaard copula、Kendall和生存Kendall函数对比分析波高和周期联合分布的4种重现水平。以位于北卡罗来纳州Duck的美国陆军工程师团FRF (Field Research Facility)实验场观测的波高与周期样本为例, 计算二者联合分布的“或”重现期、“且”重现期、Kendall重现期和生存Kendall重现期及其联合设计值。主要结论如下: 对比设定重现期, 相对于“或”联合重现期, Kendall重现期可更准确地反映波高周期联合分布的风险率; 相对于“且”联合重现期, 生存Kendall重现期可更准确地反映波高周期同时超值情况下的风险率。按目前有关规范设计要求的单变量波高设计值基本达到设计标准, 按两变量“或”重现期和波高周期两变量同频率设计值推算的设计值偏高, 以最大可能概率推算的两变量的Kendall重现期和生存Kendall重现期设计值可为海岸海洋工程安全与风险管理提供新的选择。     

台风“康森”产生的海洋近惯性能量的数值模拟研究

文章利用经验台风风场模型(TCWPM)和美国环境预测中心的气候预测系统再分析风场资料(NCEP/CFSR)对台风“康森(Conson)”进行数值模拟, 并将模拟的台风带入平板模式(slab model)模拟台风产生的海洋近惯性流。对比实测数据表明, 模拟结果与真实风场、近惯性流场均比较一致, 台风“康森”在近海面的风场不对称结构非常明显, 台风中心两侧的速度大小相差可达10m·s^-1。台风“康森”在台风中心后方产生强烈的海洋近惯性振荡, 且持续时间超过4d。海洋近惯性动能沿着台风路径呈显著的不对称分布, 表明台风“康森”在共振作用下主要在路径右侧激发强烈的近惯性振荡。研究不同强度的热带气旋产生的海洋近惯性能量, 发现热带风暴产生的海洋近惯性能量较小, 平均近惯性动能不超过35J·m^-3。随着气旋强度的增大, 热带气旋激发的近惯性能量呈指数增长, 而台风的影响面积与最大风速半径的变化相对比较一致, 当最大风速半径(R₀)增大一半(1.5R₀)时, 其产生的最大平均近惯性动能从81J·m^-3增大到631J·m^-3, 影响面积从大约600km²增加到大于900km²。     

北海银滩响应台风作用的动力地貌过程

极端高能事件影响下的海滩动力地貌过程直接关乎岸滩稳定及海堤安全。本文基于2020年16号台风“浪卡”前后北海银滩顺直岸段的剖面高程及表层沉积物等资料, 探究了中等潮差的顺直响应台风作用的地貌变化机制。结果表明: 1) 台风后海滩地貌表现为冲流带的大型沙坝消失, 后滨沙丘-滩槽体系被削平, 滩面坡度趋于平缓。2) 银滩沉积物均以中砂、细砂和极细砂为主, 三者占比超过95%; 台风后, 高潮位带沉积物变细, 低潮位带沉积物变粗, 沙坝附近则出现粗细交错式变化; 银滩中高潮位带滩面响应台风过程的特征与强潮型海滩相似, 呈现消散型海滩的特征, 而低潮位带滩面则因大型沙坝的作用而呈现弱潮型海滩特征。3) 台风期间波浪是影响海滩的主要动力因素, 海滩地形影响了近岸水动力的表现形式, 从而改变了沉积物的粒径分布。     

FY-3D卫星MWHS-2辐射率资料直接同化对台风“米娜”预报的影响*

文章基于天气研究和预报(weather research and forecasting, WRF)模式中的FY-3D卫星微波湿度计Ⅱ(micro-wave humidity sounder 2, MWHS-2)辐射率资料的直接同化模块, 采用三维变分(three dimensional variation, 3DVar)方法在晴空条件下同化MWHS-2辐射率资料, 考察MWHS-2辐射率资料同化对台风“米娜”(2019)预报的影响。文中设计了4组试验, 第一组试验不同化任何资料, 第二组试验同化了单独的全球通信系统(global telecommunications system, GTS)常规资料, 第三组试验联合同化了GTS常规资料和MWHS-2辐射率资料, 第四组试验将MWHS-2辐射率资料换成先进技术微波探测计(advanced technology microwave sounder, ATMS)辐射率资料同化。研究结果表明: 偏差订正后各通道观测和背景场差值的均值趋于0, 同化后分析场相对观测的标准差与均方根误差较背景场显著减小, 同化过程是有效的。与仅同化GTS常规资料和同化ATMS资料的试验相比, 同化晴空MWHS-2辐射率资料后的增量场在台风中心附近有负的高度增量和正的温度增量, 从动力与热力上有助于台风的维持。在确定性预报最后的12h, 同化晴空MWHS-2辐射率资料的试验能够改进500hPa环流形势的模拟, 加强西南方向引导气流的强度, 从而最终减小台风路径预报的误差。     

"868"菌粉作饲料添加剂提高甲鱼免疫力

以0.5％量添加"868"菌粉作甲鱼饲料添加剂，喂养3个月，用甲醛灭活的嗜水气假单胞菌免疫后，观察甲鱼抗体产生和中性白细胞吞噬能力的变化情况.结果表明，"868"菌粉可促进甲鱼抗体产生，且甲鱼白细胞吞噬率提高了4.1％，吞噬指数提高了8.4％.     

欧洲鳗鲡"狂奔病"的病因探讨

利用组织病理、微生物、血液电解质、寄生虫检查方法对欧鳗"狂奔病"进行分析，发现无论是淡水养殖还是海水网箱养殖，病鳗的组织病理变化基本一致，鳃、肠破坏较为明显，肝、脾、肾、心均有不同程度的充血.从微生物学的分析来看，病毒的检出率并不高，形态也不一致，细菌和寄生虫的感染多样化.病鳗的血液电解质检查结果较为一致，主要以氯离子降低为主，下降幅度在30％～50％之间.由此认为本病不象是病毒、细菌和寄生虫所致.     

基于响应面法的鮟鱇活性肽制备工艺

鮟鱇是一种低脂肪高蛋白的优质海洋生物资源, 其氨基酸含量丰富, 蛋白质含量高达75.30%。本实验选用胰蛋白酶, 胃蛋白酶, 木瓜蛋白酶和菠萝蛋白酶水解鮟鱇鱼糜, 比较各酶解产物对1, 1-二苯基-2-三硝基苯肼(DPPH)自由基的清除率, 确定木瓜蛋白酶为最佳用酶。在单因素实验基础上进行响应面优化实验, 确定酶解反应的最佳条件为: 加酶量829.51 U/g, pH值7.37, 酶解温度47.09 ℃, 酶解时间5.86 h, 液固比5.79∶1。在最优条件下验证其DPPH自由基清除率为80.22%±0.63%, 接近预测值80.55%。经响应面法实验制备的鮟鱇活性肽粉末呈淡黄色, 具有较好的抗氧化活性, 其羟自由基清除能力的IC₅₀值为1.69 mg/mL, 可作为潜在的抗氧化剂。     

赤道东经90°海岭活塞柱状心钙同位素曲线特征及其古环境意义

A δ~(44) Ca curve from shells of the planktonic foraminifera Globigerinoides sacculifer in calcareous biogenic oozes has been extracted from the Nintyeast Ridge in the Indian Ocean since 300 ka. By combining terrigenous inputs(e.g., grain size, magnetic susceptibility, and turbidite frequency) with the oceanic productivity(e.g., biogenic content and Neogloboquadrina dutertrei content), it is found that the curve's variations are closely related to the historical evolution of the oceanic calcium cycle. The δ~(44)Ca value is in lower tendency and has small oscillation during Marine Isotope Stage(MIS) 6, when the supply of terrigenous detrital is highest. In contrast, during MIS 3,5 and 7, the δ~(44) Ca values are in higher tendency, and their fluctuations are consistent with the variations of the productivity proxies. These results suggest that the calcium isotopes are mainly influenced by the input of the Himalayan erosion products to the northern Indian Ocean. In addition, the developmental stages of calcareous planktons may have a secondary impact on the fluctuations of the calcium isotope ratio of sea water.     

珠江口红树林基围养殖生态开发模式评述

起源于珠江三角洲的红树林基围(land-based enclosure)养殖传统模式是红树林可持续利用和生态开发范例之一。本文介绍了珠江口红树林基围养殖生态开发模式的3个个例: 仅存香港米埔红树林自然保护区的传统基围养殖运作历史和演变, 及其候鸟生境、养殖、观鸟、环境教育综合功能的实现; 珠海淇澳岛大围湾红树林传统和粗放式基围养殖试验和围内水位盐度等环境条件变化对红树林生长影响的研究; 伶仃洋东岸海上田园红树林海水种植-集约式养殖系统试验和红树林净化水质研究。在珠江口红树林保护管理及海域污染防治过程中建议重视红树林可持续利用模式的研究和推广, 建立新的基围养殖示范区, 大力推广红树林基围养殖的生态开发模式, 探索毁林养殖区红树林友好式整治模式, 改善红树林基围养殖技术提高养殖产量, 加强红树林基围养殖系统相关科学研究。     

Short-term residence and movement patterns of the annular seabream Diplodus annularis in a temperate marine reserve

The short-term movements of a small temperate fish, the annular seabream Diplodus annularis (Linnaeus 1758), were examined using standard tag-recapture and passive acoustic telemetry in Palma Bay (NW Mediterranean), a marine protected area (MPA). The study aimed to provide valuable information for assessing the recreational fishery and its results suggest that MPAs can be used to protect the adult stock of D. annularis. All the fish tagged with standard tags were recaptured near the release locations, with a maximum distance of ∼300 m. The maximum time between release and recapture was 185 d. Two different arrays of acoustic receivers were deployed, one in 2008 and another in 2009, within the MPA. Twenty adults were surgically tagged with acoustic transmitters. Fish monitored in 2008 (n = 12) were translocated from the point of capture to analyse the movement behaviour after artificial displacement. Upon release at displaced locations, 67% of the fish moved towards the original capture location using a time of return that ranged from 0.75 to 15.25 h. Fish monitored in 2009 (n = 8) were released at the point of capture. They showed high site fidelity with a maximum period of 27 d between the first time and the last time they were detected.     

A video-based technique for mapping intertidal beach bathymetry

Measuring the location of the shoreline and monitoring foreshore changes through time are core tasks carried out by coastal engineers for a wide range of research, monitoring and design applications. With the advent of digital imaging technology, shore-based video systems provide continuous and automated data collection, encompassing a much greater range of time and spatial scales than were previously possible using field survey methods.A new video-based technique is presented that utilises full-colour image information, which overcomes problems associated with previous grey-scale methods, which work well at steep (reflective) sites, but are less successful at flatter (dissipative) sites. Identification of the shoreline feature is achieved by the automated clustering of sub-aqueous and sub-aerial pixels in ‘Hue–Saturation–Value’ (HSV) colour space, and applying an objective discriminator function to define their boundary (i.e., ‘shoreline’) within a time-series of consecutive geo-referenced images. The elevation corresponding to the detected shoreline features is calculated on the basis of concurrent tide and wave information, which is incorporated in a model that combines the effects of wave set-up and swash, at both incident and infragravity frequencies.Validation of the technique is achieved by comparison with DGPS survey results, to assess the accuracy of the detection and elevation methods both separately and together. The uncertainties associated with the two sub-components of the model tend to compensate for each other. The mean difference between image-based and surveyed shoreline elevations was less than 15 cm along 85% of the 2-km study region, which corresponded to an horizontal offset of 6 m. The application of the intertidal bathymetry mapping technique in support of CZM objectives is briefly illustrated at two sites in The Netherlands and Australia.     

Solution of an unstable axisymmetric Cauchy–Poisson problem of dispersive water waves for a spectrum with compact support

 It has been known that the axisymmetric Cauchy–Poisson problem for dispersive water waves is well posed in the sense of stability. Thereby time evolution solutions of wave propagation depend continuously on initial conditions. However, in this paper, it is demonstrated that the axisymmetric Cauchy–Poisson problem is ill posed in the sense of stability for a certain class of initial conditions, so that the propagating solutions do not depend continuously on the initial conditions. In order to overcome the difficulty of the discontinuity, Landweber–Fridman's regularization, famous and well known in applied mathematics, are introduced and investigated to learn whether it is applicable to the present axisymmetric wave propagation problem. From the numerical experiments, it is shown that stable and accurate solutions are realized by the regularization, so that it can be applicable to the determination of the ill-posed Cauchy–Poisson problem.     

Body size–abundance distributions of nano- and micro-phytoplankton guilds in coastal marine ecosystems

This study focuses on body size–abundance distributions of nano- and micro-phytoplankton guilds in coastal marine areas of the Southern Adriatic–Ionian region. The aim of the study was to evaluate the occurrence of common patterns of body size–abundance distributions in relation to physical, chemical and biological environmental forcing factors and to taxonomic composition of phytoplankton guilds. This paper is based on data collected during four oceanographic cruises carried out seasonally along the Southern Apulian coast (Adriatic and Ionian Seas, SE Italy) as a part of the INTERREG II Italy–Greece Program. The study was performed at 21 stations located on 7 transects perpendicular to the coastline, with 3 stations per transect at a distance of 3, 9 and 15 NM from the coastline. At each station, profiles of the major physical features of the water were determined and water samples were collected for phytoplankton and nutrient analysis. Overall, 320 nano- and micro-phytoplankton taxa were identified, 76% of which at species level, with phytoplankton cells ranging in size from 0.008 to 4697.54 ng. Body size–abundance distributions showed some common features: they were relatively invariant (average similarity 65%) with respect to taxonomic composition (average similarity 32%), right skewed (90%), leptokurtic (77%) and log normal (76%). Moreover, abiotic, biotic and spatial ecosystem components accounted for up to 75% of body size–abundance distribution variation. The results of this study suggest that body size–abundance distributions are an intrinsic property of marine phytoplankton communities, emphasising functional dependence on ecological constraints related to trophic factors and intra-guild coexistence relationships.     

Directional spectrum of ocean waves from array measurements using phase/time/path difference methods

Wave direction has for the first time been consistently, accurately and unambiguously evaluated from array measurements using the phase/time/path difference (PTPD) methods of Esteva in case of polygonal arrays and Borgman in case of linear arrays. We have used time series measurements of water surface elevation at a 15-gauge polygonal array, in 8 m water depth, operational at the CERC's Field Research Facility at Duck, North Carolina, USA. Two modifications have been made in the methodology. One modification is that we use the true phase instead of the apparent phase, the other modification being that estimates of wave direction are registered only if the relevant gauges in the array are coherent at 0.01 significance level. PTPD methods assume that in a spectral frequency band the waves approach from a single direction, and are simple, expedient and provide redundant estimates of wave direction. Using Esteva's method with the above modifications, we found that at Duck: (i) the directions of swell and surf beat, when energetic swell is present, conform to the schematic diagram of surf beat generation given by Herbers et al., (ii) surf beat of remote origin occurs when the significant wave height, H_mo, falls below 0.41 m, (iii) the surf beat of remote origin is not normally incident at the shore contrary to Herbers et al. In fact we found that the surf beat of remote origin is incident at angles in excess of 45° with respect to the shore normal, and (iv) the surf beat of remote origin is largely trans-oceanic in origin.     

Metal distributions and their fluxes at the coastal boundary of a semi-enclosed ria

Water column samples have been collected in the outer channel of the Ferrol Ria (NW Spain) during four occasions over a tidal cycle. The objective was to study the exchange of dissolved and particulate Cd, Cu, Pb and Zn and particulate Al, Fe and Si between the ria and the adjacent coastal waters. This study provides the first extensive dataset on dissolved and particulate metal concentrations in the water column of a Galician ria. Typical concentrations of dissolved Cd (96 ± 31 pM), Cu (8 ± 4 nM), Pb (270 ± 170 pM) and Zn (21 ± 10 nM) were similar than in other European Atlantic shelf and coastal waters. The fraction of metals in the particulate phase followed the trend: Pb > Cu Zn > Cd. The outgoing water from the ria was enriched in dissolved and particulate Cu, Pb and Zn compared with incoming waters, whereas Cd concentrations were similar for both waters. The suspended particulate matter was composed of a mixture of marine and continental material. The latter end-member was found to arise from the metal-rich ria bed sediments, which is diluted by the dominant metal-poor marine end-member. The net output flux of Cu from the channel is balanced by the freshwater inputs to the ria, and the net Zn flux gave a positive output to coastal waters. For Pb, the net flux to the coastal waters is less than that input from the rivers, as a result of its particle reactivity and deposition in sediments. On the contrary, a net input flux of dissolved Cd from coastal waters was observed, highlighting the oceanic source of this metal in the Galician rias. Results from the budget calculations are in agreement with the differential geochemical behavior of these elements in coastal waters.     

Parameter estimation for basin-scale ecosystem-linked population models of large pelagic predators: Application to skipjack tuna

A Spatial Ecosystem and Population Dynamic Model (SEAPODYM) is used in a data assimilation study aiming to estimate model parameters that describe dynamics of Pacific skipjack tuna population on ocean-based scale. The model based on advection–diffusion–reaction equations explicitly predicts spatial dynamics of large pelagic predators, while taking into account data on several mid-trophic level components, oceanic primary productivity and physical environment. In order to improve its quantitative ability, the model was parameterized through assimilation with commercial fisheries data, and optimization was carried out using maximum likelihood estimation approach. To address the optimization task we implemented an adjoint technique to obtain an exact, analytical evaluation of the likelihood gradient. We conducted a series of computer experiments in order to (i) determine model sensitivity with respect to variable parameters and, hence, investigate their observability; (ii) estimate observable parameters and their errors; and (iii) justify the reliability of the computed solution. Parameters describing recruitment, movement, habitat preferences, natural and fishing mortality of skipjack population were analysed and estimated. Results of the study suggest that SEAPODYM with achieved parameterization scheme can help to investigate the impact of fishing under various management scenarios, and also conduct forecasts of a given species stock and spatial dynamics in a context of environmental and climate changes.     

A comparison of two formulations of barotropic–baroclinic splitting for layered models of ocean circulation

In numerical models of ocean circulation, it is widespread practice to split the fast and slow motions into barotropic and baroclinic subsystems, respectively. In the case of the baroclinic equations, the dependent variables can either be (1) slowly-varying baroclinic quantities, obtained from splitting the original flow variables into barotropic and baroclinic components, or (2) the original unsplit variables, which can vary on both the fast and slow time scales. In the second case, the variables in each layer are adjusted after each (long) baroclinic time step to ensure compatibility with the results produced from the barotropic equations. The second approach can be applied to the layer thickness equation to ensure exact conservation of mass within each layer. In the case of the momentum equations, the second approach amounts to replacing unresolved fast portions of Coriolis and pressure forcing with time averages of well-resolved forcing from the barotropic system. In this study, both approaches for the momentum equations are evaluated, in several test problems, by comparing to analytical solutions or to solutions computed with an unsplit code that uses short time steps. The two methods give very similar results in some simple problems for which analytical solutions are known. However, in some eddying double-gyre simulations, the formulation with unsplit variables requires a significant reduction in the baroclinic time step in order to avoid numerical difficulties that include grid noise and inaccurate representation of the flow field. In contrast, the formulation with split variables does not display such difficulties, and in those same examples it can be used with zero explicit horizontal viscosity. All of these computations employ a two-level time-stepping method that was previously developed by the author.