海上固定平台雷达测波技术及典型数据处理算法

首先总结了国内外海上固定平台使用的多种非接触式波浪测量方法,比较了不同测波方法的适用性。针对不同的测量方法给出了常用的传感器与设备,同时提供了每种设备的主要生产销售商。然后,对单点测波雷达和X波段雷达测波算法进行了综述,给出了波面的时间序列和雷达影像的时空序列两种数据的处理过程。最后,提出了波浪测量技术存在的一些问题,以期为我国海洋环境监测与观测系统的完善提供参考。     

Reef parameterisation schemes with applications to tidal modelling

A variety of analytical models is used to investigate the effects on tidal propagation of a barrier reef system. These models specify reef geometry by two parameters. They can accommodate cases where water flows over reefs, as well as through inter-reef gaps, and also incorporate quadratic bottom friction. Although based on a one-dimensional approach, adaptations of a solution by Huthnance are used to account for the additional blockage effects associated with two-dimensional flow patterns near reef barriers. The present work adopts the philosophy that only a numerical approach can cope with the wide variations in reef geometry that are encountered in areas such as the Great Barrier Reef (GBR) region of Australia. Moreover, since typical model grids cannot resolve inter-reef gaps and other features with sufficient accuracy, a parameterised approach is needed to accommodate the conflicting demands of reef geometry and an economically feasible model resolution. The formulation of the analytical models is such that they can be applied immediately to standard numerical algorithms. Numerical experiments for flow in a channel, with a reef barrier across its centre, are used to test the parameterisation schemes. Comparison of the results for parameterised reefs with those obtained using extremely fine grids, shows convincing evidence of the success of the schemes. A separate method for automatically generating reef parameters has simplified the task of applying the methodology to real reefal systems. A tidal model of the Southern GBR, a region which exhibits unusual tidal behaviour, but which also has ample field data available for model testing, is used to demonstrate the accuracy that can be attained with the parameterised approach. Although tides are considered specifically in the present work, the formulation should be applicable with equal ease to the many other significant classes of low frequency motions in the GBR.     

Methods for detecting regime shifts in large marine ecosystems: a review with approaches applied to North Pacific data

This note provides a brief review of five analytical methods previously used or promoted for diagnosing regime shifts in marine ecosystems. The methods discussed are: (i) principal components analysis, (ii) compositing average standard deviates, (iii) autoregressive moving average and intervention analysis modeling, (iv) vector autoregressive process modeling, and (v) Fisher information. Assessments of the relative strengths and weaknesses for the different analytical approaches are also offered. Some of these methods are applied to a collection of fishery oceanographic time series for the N. Pacific to illustrate aspects of their relative utility and limitations for diagnosing regime shift behavior. One recommendation for future studies is to analyze biotic and abiotic time series separately in order to identify ecosystem state variables of interest and to better isolate ecosystem behaviors from other influences like environmental change. Methods that allow for quantitative assessments of the statistical significance of hypothesized regime shifts should be favored over those that do not. Analyses of especially large collections of time series may benefit from first using a data compression technique and then applying one of the methods that are more appropriate for just one or a small number of time series. Because of the difficulties in observing and adequately documenting many aspects of marine ecosystem variability, it is crucial that future research attempt to combine empirical studies of large marine ecosystems with theoretical and modeling studies of other systems for which the dynamics and predictability are better understood. With such a comparative approach it should be possible to refine conceptual and simulation models, while also identifying crucial gaps in existing observations.     

Analysis of correlations between time series with the use of the phase spectrum

In connection with the problem of revealing cause-effect relations among different climatic characteristics, methods for determining the dependence between time series on the basis of selected auto-and cross-covariance functions and periodograms expressed in terms of the Fourier coefficients of the initial series are discussed. Real time series do not always satisfy the conditions of statistical stationarity, so that their analysis requires a combination of statistical and deterministic approaches. The possibility of using the above numerical characteristics in relation to such series is considered. Characteristic features of describing finite segments of time series with the use of their Fourier coefficients is studied in detail. The main emphasis is on the determination of the time shifts (delays) at which the covariance between the series is maximal. The problems that appear during a practical implementation of the periodogram method for shift estimation are discussed. A previously unknown formula that is necessary for further studies and relates the Fourier transform of a selected correlation function to the periodogram of the series is derived.     

Algorithms for automatic,real-time tsunami detection in wind–wave measurements Part I: Implementation strategies and basic tests

Several, although not all, wind–wave gages are equipped with sensors capable of detecting sea-level oscillations within the tsunami frequency band. The present paper looks at the algorithms to be implemented in the software of these gages in order to automatically perform the real-time detection of a possible tsunami within recorded signals. In particular, a new algorithm is proposed and tested. The first part of the paper concentrates on the algorithms' characteristics, implementation strategies and basic testing. First of all, the situations in which wind–wave measurements are either essential, or useful for real-time tsunami detection are discussed. In the second place, already existing algorithms are recalled, specifying their characteristics and fields of application. Then, the characteristics of the new proposed algorithm – mainly based on an infinite impulse response, time domain filter – are illustrated and analyzed. Performance and efficiency of the considered algorithms are compared using synthetic time series. The second part of the paper discusses the algorithms' use in the framework of Tsunami Early Warning Systems (TEWS), testing them in actual cases.     

基于Prophet算法的海南近海波浪长时段时序分析与预测

近年来,以大数据为基础的人工智能算法逐步兴起并被用于海洋波浪短期预测.本文采用2015-2019年海南近海逐时波浪实测时序数据,基于Prophet算法建立了海南近海波浪长时段时序预测模型,分析了2015-2019年海南近海波浪日、月、年变化特性,并对海南近海2020年波浪变化过程进行了预测.结果显示,Prophet算法...     

三种胡子鲶形态特征的统计分析及其分类意义

本文对胡子鲶Clarias fuscus、两栖胡子鲶Clarias batrachus及革胡子鲶Clarias lazera共125尾样品的10项形态测量性状及5项可数性状进行比较研究,并应用主分量分析和判别分析探讨种(或群体)间的分类关系。多变量统计分析结果:三种胡子鲶种间具有明显的间断,正判率均为100％;而胡子鲶的两个群体间的正判率为93.5％,并且没有明显的间断。研究结果与生化分析结果基本一致,表明中国存在两栖胡子鲶,三种胡子鲶是三个独立的种,区分三者的最有效特征为鳃耙数。我们认为,主分量分析和判别分析对鉴别外形非常相似的种类(如胡子鲶和两栖胡子鲶)有实用价值。     

Analysis of Rhythms in Experimental Signals

We compare algorithms designed to extract quasiperiodic components of a signal and estimate the amplitude, phase, stability, and other characteristics of a rhythm in a sliding window in the presence of data gaps. Each algorithm relies on its own rhythm model; therefore, it is necessary to use different algorithms depending on the research objectives. The described set of algorithms and methods is implemented in the WinABD software package, which includes a time-series database management system, a powerful research complex, and an interactive data-visualization environment.     

数据挖掘算法在河口羽状流数据分析中的应用

羽状流的近场扩散角作为河口动力学的关键参数,对河流入海物质的输运扩散过程有重要影响,而在真实环境中由于受到复杂因素的影响,羽状流扩散角存在着显著的变化.数据挖掘技术尽管在地学数据的应用上尚处于探索阶段,但研究这一问题提供了一种有效途径.本文基于马格达莱纳河羽状流近场扩散角及周边环境数据,利用多重数据挖掘算法开展数据分析...     

渤海AVHRR多通道海冰密集度反演算法试验研究

为了得到更精确的渤海海冰密集度反演参数,采用辽东湾不同类型海冰ASD实测数据,在分析光谱特征的基础上,针对NOAA/AVHRR数据确定出合适海冰密集度反演算法阈值。继而,基于线性光谱混合模型的多通道反演算法进行了一系列算法试验。同时实现了基于LandSat5-TM数据的渤海海冰密集度场反演,并利用该结果与AVHRR单通道和多通道算法得到的海冰密集度反演结果进行比对分析。定量误差分析结果表明,当单通道算法或组合算法中包含1通道时,与Landsat5-TM反演结果的平均误差为正值,包含2通道且不包含1通道时,平均误差为负值;同时使用这两个通道较只包含其一的各种组合算法的平均误差明显偏小;在各种组合算法中,1245四个通道组合反演的海冰密集度结果误差最小,可应用于渤海AVHRR数据海冰密集度反演。     

Influence of Gaps Between Multiple Floating Bodies on Wave Forces

The present study aims to give general hints about hydrodynamic interactions for water wavediffraction on a super large floating structure composed of a large number of box-shaped modules withmany small gaps in between.And meanwhile,it also aims to seek for an effective way to take the gap influ-ence into consideration without numerical difficulties existing in conventional methods.An asymptotic ma-tching technique is exploited by virtue of the smallness of gaps.Formal potential solutions are establishedfor the near field around the gap ends and the far field away from gap ends,respectively,and theunknowns in those solutions are uniquely determined by asymptotic matching.The eigen-function expan-sion method is used for the outer far field and a series of pulsating sources at each gap end is introduced tosimulate the gap influence.Strong hydrodynamic interaction is observed and a new resonant phenomenon,the mechanism of which differs absolutely from any known ones,is revealed in the present study.Sharppea     

Convergence criteria for axisymmetric Green's function with application to floating bodies

Convergence criteria are provided for truncating the evanescent eigenmode series in the Green's function for vertical, axisymmetric bodies of revolution. To numerically compute the strength of the source distribution for both the exciting and restoring forces, separate criteria are required for the off-diagonal and for the diagonal elements in the matrix of coefficients for the source strengths. The Black-Fenton algorithms for wave-induced exciting forces on vertical axisymmetric bodies of revolution are extended to include the wave-induced restoring forces. The Gauss-Seidel matrix version method recommended by Fenton is compared with the Gauss elimination method and is found to be non-converging for near deep water wave conditions. Comparison between theory and measured data for the dynamic response of a discus buoy demonstrates the convergence criteria over a range of dimensionless frequencies in relatively deep water wave conditions.     

Decision support tools in marine spatial planning: Present applications,gaps and future perspectives

Evidence-based decision making is an essential process for sustainable, effective, and efficient marine spatial planning (MSP). In that sense, decision support tools (DSTs) could be considered to be the primary assistant of planners. Although there are many DSTs listed in tool databases, most of them are conceptual and not used in real MSP implementation. The main objective of this review is to: (i) characterize and analyse the present use of the DSTs in existing MSP implementation processes around the world, (ii) identify weaknesses and gaps of existing tools, and (iii) propose new functionalities both to improve their feasibility and to promote their application. In total, 34 DSTs have been identified in 28 different MSP initiatives with different levels of complexity, applicability and usage purposes. Main characteristics of the tools were transferred into a DST matrix. It was observed that limited functionality, tool stability, consideration of economic and social decision problems, ease of use, and tool costs could be considered as the main gaps of existing DSTs. Future developments are needed and should be in the direction of the specific need of marine planners and stakeholders. Results revealed that DST developments should consider both spatial and temporal dynamics of the ocean, and new tools should provide multi-functionality and integrity; meanwhile they should be easy to use and freely available. Hence, this research summarised current use, gaps, and expected development trends of DSTs and it concludes that there is still a big potential of DST developments to assist operational MSP processes.     

Statistical analysis of series of dendrochronological indices

We analyze series of tree-ring indices to understand whether they can be indicators of long-term climate changes. We calculated the synchronous cross-correlation coefficients (CCs) for all possible pairs composed of nine series, of which only one CC (for a pair of the longest series) proved to be sufficiently high (0.72). We revealed a time interval for which this CC is equal to 0.88. We failed to locate sufficiently larger time intervals with a higher CC for other pairs of series. Similar calculations for a series using a low-frequency filter (with allowance for periods of 100 or more years) led to a noticeable decrease in almost all CCs. This confirms the statements circulating in the literature that tree-ring chronologies include climate signals with characteristic times of several decades and that the secular and supersecular oscillations are significantly distorted as a result of standardization and cross-linking. The results presented in this paper show that the complex of series being considered cannot be used as a climate-change indicator without an additional analysis. Here, we describe a possible procedure for such analysis. As a result, we found that only two time series at some time subinterval can provide useful information about climate changes.     

Asymptotic performance of a pulse-to-pulse incoherent Doppler sonar in an oceanic environment

Active Doppler sonar systems are gaining popularity as a method to profile remotely the oceanic velocity field. Estimation of the variance with which an ideal single.beam sonar system measures relative Doppler motion is the subject of this paper. Theoretical formulations, simulated reverberation data, and sea data are considered to determine this variance. The sea data considered in this paper were selected carefully to avoid performance degrading physical/instrumental phenomena and bias corrected to remove further instrumental effects. Asymptotic performance, determined in this research, is realized when instrumental and physical phenomena do not measurably affect experimental performance. Oceanic and simulated data sets are processed with several velocity-estimation algorithms that are implemented in existing sonar systems. These algorithms are compared against each other and the velocity-estimation standard-deviation results tabulated. The algorithms are shown to possess similar performance characteristics when simulated, and sea data are processed in spite of the fact that some of these algorithms are suboptimal from a theoretical viewpoint. The results of this study show that the asymptotic performance of the Doppler system examined is approximately 25 percent above a theoretical lower bound.     

Data recording and processing for high-resolution frequency analysis

This paper discusses the practical considerations associated with analyzing analog data signals to very high resolution in frequency. In the problem considered here, the data set is recorded on analog tape, digitized, and processed on a digital computer. A primary concern is that recorder speed variations, or flutter, can produce artifacts which might become evident when high-resolution spectral analysis is performed. This study concludes that fractional millihertz analysis resolution can be achieved with existing analog tape recorder technology. Another problem which must be considered is the efficient storage of the large data sequences resulting from processing long-time signal records. The use of two-stage frequency analysis is described as an approach to addressing this problem. Finally, the implementation issues associated with the periodogram and AR (autoregressive) estimation algorithms are outlined. It is anticipated that the discussion of practical considerations given here will be useful to researchers who must address problems that are similar to those cited in this paper.     

Numerical modeling of ocean hydrodynamics with variational assimilation of observational data

Models and methods of the numerical modeling of ocean hydrodynamics dating back to the pioneering works of A.S. Sarkisyan are considered, with emphasis on the formulation of problems and algorithms of mathematical modeling and the four-dimensional variational assimilation of observational data. An algorithm is proposed for studying the sensitivity of the optimal solution to observational data errors in a seasurface temperature assimilation problem in order to retrieve heat fluxes on the surface. An example of a solution of the optimal problem of the World Ocean hydrodynamics with the assimilation of climatic temperature and salinity observations is offered.     

Simulation of nonlinear wave run-up with a high-order Boussinesq model

This paper considers the numerical simulation of nonlinear wave run-up within a highly accurate Boussinesq-type model. Moving wet–dry boundary algorithms based on so-called extrapolating boundary techniques are utilized, and a new variant of this approach is proposed in two horizontal dimensions. As validation, computed results involving the nonlinear run-up of periodic as well as transient waves on a sloping beach are considered in a single horizontal dimension, demonstrating excellent agreement with analytical solutions for both the free surface and horizontal velocity. In two horizontal dimensions cases involving long wave resonance in a parabolic basin, solitary wave evolution in a triangular channel, and solitary wave run-up on a circular conical island are considered. In each case the computed results compare well against available analytical solutions or experimental measurements. The ability to accurately simulate a moving wet–dry boundary is of considerable practical importance within coastal engineering, and the extension described in this work significantly improves the nearshore versatility of the present high-order Boussinesq approach.     

Sea surface wind and Sea ice in the Barents Sea using microwave sensing data from Meteor-M N1 and GCOM-W1 satellites in January–March 2013

Application of satellite passive microwave sensing for the retrieval of key climatic parameters in the Barents Sea is considered. Fields of surface wind, atmosphere water vapor content and cloud liquid water content were found from MTVZA-GY radiometer onboard the Meteor-M N1 satellite and AMSR2 onboard the GCOM-W1 satellite with the use of original algorithms. The fields are in a good agreement with the ancillary remote and in situ measurements, which follows from the analysis of the evolution of the extra tropical and polar cyclones and cold air outbreaks with storm winds leading to intense air-sea interaction, and the formation and drift of sea ice.