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海浪预报知识讲座 第一讲 海浪及其危害 总被引：2，自引：0，他引：2
第一讲海浪及其危害１海浪的定义海浪是发生在海洋中的一种海水波动现象。一般指的海浪是由风产生的波动，其周期为０．５至２５秒，波长为几十厘米到几百米，一般波高为几厘米到２０米，在罕见的情况下波高可达３０米以上。在观测到的资料中［１］，有许多关于实测最大波高的记录：１９３３年２月７日在北太平洋，美国海军的莱梅帕号油船观测到最大波高达３４米，周期１４．８秒和波速１０２公里／小时的海浪；１９５６年４月２日苏联调查船“鄂毕号”在印度洋的南纬４０度风暴区域，于风速３５米／秒时，使用立体照相测量得到最大波高为２… 相似文献
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本文根据大连老虎滩海洋站1963-1987年的海浪实测资料,对大连南部近海海域的海浪分布状况进行统计分析,得出E-SW方向为本区海浪的强浪方向,年平均波高为0.4米。并推算出25年、50年一遇的最大波高为4.9米和5.3米。 相似文献
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根据１９６０－１９８９年南麂海洋站的实测风浪资料，分析了该海域的风浪特征，结果认为：这个海域的浪通常是混合浪，常见浪是三级波高的浪；海浪要素的均值分布比较平稳，极值具有不均匀分布的特性，本区的波高和周期的联合分布表明，波高在０．５－１．９ｍ，周期为４．０－６．９ｓ类型的浪在该海域出现频率最高，此外，引用最大熵谱方法找出了本区波高，周期和风速的主要变化周期，还讨论了台风浪的周期与最大波高的经验关系。 相似文献
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由模拟波面统计分析波高—周期联合分布 总被引：4，自引：0，他引：4
阐述以实测或拟合海浪谱为靶谱，用等能量分割法作波面数值模拟，从而利用模拟波面统计分析波高（Ｈ）－周期（Ｔ）联合分布，对波候的Ｈ－Ｔ联合分布，长时段海浪连续记录的Ｈ－Ｔ联合分布以及风浪，涌浪和混合浪的Ｈ－Ｔ联合分布进行了讨论，结果表明，只要已知特征波高和周期，就可反演出模拟波面，进而估测Ｈ－Ｔ联合分布情况，这对了解与各种特征波高对应的周期问题及在海洋工程应用上有一定的参考意义。 相似文献
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利用青岛海洋大学海洋实验室现代化的大型水槽,设计进行了多种海浪强度下,由深水传入近岸不同坡度水底上的变浅随机海浪的模型实验,依据实验资料统计分析结果表明,对近岸变浅随机海浪而言,其波高分布不再符合Ｒａｙｌｅｉｇｈ分布,与ГЛУФОВСКИЙ的经验分布也有差异,它不仅与参量Ｈ＝Ｈ／ｄ有关,且与表征深水海浪的波形特征量Ｈ０／Ｔ０有关,并获得其经验关系,为实验应用变浅随机海浪的波高统计分布提供了可能。 相似文献
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将共轭变分同化方法应用于LAGFD－WAM海浪数值模式，导出了海浪谱能量平衡方程的共轭方程以及风输入、破碎、底摩擦、波波非线性相互作用和波流相互作用的相庆共轭源函数，建立了海浪同化模型，数值计算仍采用特征线嵌入计算格式，为合成孔径雷达波谱反演资料和卫星高度计有效波高资料同化奠定理论基础。 相似文献
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本文根据相干斑噪声的时间快变特征和非海浪纹理现象的时间缓变特征，基于交叉谱提出了一种对相干斑噪声和大尺度非海浪纹理的抑制的方法，进而结合SAR图像谱和海浪谱之间的准线性映射关系，基于SAR数据对海浪参数进行了反演。在反演过程中，首先仿真分析了不同海况下准线性近似法的海浪反演能力，结果表明：风浪引起的方位向截断效应会显著影响反演精度，因此该方法在低风速时的涌浪反演精度更高。通过将基于Sentinel-1卫星2020年的波模式SAR数据的反演结果与欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts, ECMWF)提供的再分析数据进行对比，发现高海况海浪有效波高反演结果明显偏低，而且该反演误差与风速、方位向截断波长之间存在显著相关性。为了提高有效波高的反演精度，本文进一步给出了海浪有效波高反演误差与风速、方位向截断波长之间的经验校正函数模型，结果显示，通过该模型修正后的海浪有效波高反演结果与ECMWF数据和浮标测量数据具有良好一致性。 相似文献
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设计了一系列理想的数值实验,利用高分辨率的WAVEWATCHIII海浪模式定量分析热带气旋移动速度、强度、最大风速半径和热带气旋移动时的转向等风场细节因素对热带气旋下表面海浪分布特征的影响。实验结果表明,热带气旋移动速度、最大风速半径和热带气旋移动时的转向会影响海浪的空间非对称分布。最大风速半径增大会使最大有效波高的位置向后移动,而移动速度增大会使最大有效波高位置向前移动。移动速度增大会使右侧象限内的有效波高增大,左侧象限内有效波高减小。最大风速半径增大和强度增强使各象限内有效波高均增高。热带气旋的转向使各象限内有效波高增高,除了右后象限。这些风场特征对各个象限内海浪的平均波长、平均周期、平均波向、和波峰方向都有很重要的影响,尤其以左后象限最为显著。 相似文献
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在对分形理论进行概述的基础上，对海况延续性和长期波高序列的统计分形特性进行了分析。分析得出海况的平均延时与波高阈之间具有分形关系。长期波高序列的R／S分析表明长期波高序列不是相互独立的，而是具有“记忆性”和持久性，其Hurst指数明显大于通常的时间序列。最后探讨了波浪分形特性的波侯意义，并对其应用前景进行了展望。 相似文献
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CHEN Dake 《海洋学报(英文版)》2008,27(Z1):1-8
Because of its vast volume and heat capacity, the ocean contains most of the memory of the earth's ocean - atmosphere coupled system. It has been suggested that the ocean may delay global warming by absorbing large amounts of heat, that it may cause ab- rupt climate change due to its disrupted thermohaline circulation, and that it may set the time-scales for various climate oscilla- tions. Although the slow pace and persistence of oceanic variations give hope to long-range prediction, there still exist large uncer- tainties in climate predictability. Presently available observations and models are generally inadequate for studying and predicting long-term climate changes. However, some short-term fluctuations such as ENSO have been well studied and shown to be highly predictable even with simplified models. 相似文献
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C. Graham 《Coastal Engineering》1982,6(4)
This study sets out to define the basic forms in which wind speed and wave height persistence statistics may be defined for offshore engineering applications, and describes the development of a mathematical persistence model.The model incorporates some of the principles laid down by other workers, but it is fundamentally based on a new concept for parameterising persistence statistics, linking wind speed and sea state percentage probability of exceedance with the persistence average duration.North Sea measured wind and wave data have been used to calibrate and test the model. During the course of these test runs it proved necessary to fine tune the basic Weibull equation of the model, but following these adjustments the model runs were found to correlate well with the measured data.It is concluded that the model may be used to predict wind speed and wave height persistence statistics with acceptable accuracy for preliminary stage oil industry planning purposes and that the calibrated model has particular application for those areas where little measured data are currently available. 相似文献
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The use of fractal geometry to evaluate seagrass scaling behavior and the persistence of seagrass landscape patterns in relation to a disturbance is presented in this paper.Ria Formosa is a dynamic barrier-island system with a migrating inlet that creates a cyclic disturbance in a seagrass landscape. Seagrass patches which develop in the intertidal and shallow subtidal areas of Ria Formosa were digitized from a temporal sequence of aerial photographs, from 1980 to 1998. The methodology used to evaluate seagrass scaling behavior was proposed by Meltzer and Hastings (1992), and relates the frequency distribution of patch size with the existence of patch size-related patterns. The Hurst exponent was calculated to assess the temporal persistence of the seagrass landscape. Univariate regression was used to investigate relations between temporal persistence and disturbance. The existence of patch size-related patterns was identified for all years suggesting shifts in generating processes occurring at different domains of scales in the seagrass landscape. The results enforces the idea that it is important to recognize the existence of diverse processes occurring at different domains of scales and, emphasizes the importance of evaluating issues of temporal and spatial scale while trying to understand changes in seagrass landscapes. The Hurst exponent estimates show that although the migration and relocation of the inlet affected this system the evolutionary trajectory of the seagrass landscape is persistent, i.e., the patch dynamics observed is stable. Furthermore, persistence values were different for differently sized patches, small patches having lower persistence then larger patches. 相似文献
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Results are summarized of an investigation concerned with the development and validation of a method for estimating persistence statistics from cumulative probability distributions. Primary attention has been devoted to estimations of wave height persistence and the motivation has been the requirement to provide estimates of persistence statistics as an additional output for the wave climate synthesis programme called NMIMET which can provide data on a worldwide basis. The opportunity has also been taken to adapt the methods developed for application to estimation of wind speed persistence.A method due to Graham is taken as the starting point and is modified in the light of detailed examination of a number of measured data sets. The method thus derived is shown to be more reliable and much simpler to apply than Graham's method and to give results in good agreement with a range of measured data sets for both exceedance and non exceedance. The measured data used for validation include 2 sets in areas remote from the sites in UK waters used for most of the development. A comparison is also included between persistence statistics estimated using NMIMET output of wave height probabilities from visual wave data and results from measured data. 相似文献
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海面高度异常 （SSHA） 作为重要的海洋要素，对研究海洋温盐剖面、海洋涡旋等海洋动力现象具有重要意义。然而，传统的海洋预测技术存在着预测时效过短、预测过程复杂等诸多问题，现有的机器学习预测方法也只针对几个点或区域
进行平均，忽略了很多重要信息。因此，本文提出了一种基于经验正交函数和 BP 神经网络 （一种机器学习方法） 的 SSHA预测模型 （EOF-BPNN） 来实现对起报时刻后 30 天的南海 SSHA 预测。首先，对 1993 年 1 月 1 日—2013 年 12 月 31 日的逐日 SSHA 数据进行距平归一化预处理，构建相关系数矩阵，并对该矩阵进行 EOF 分解，获取主成分。然后将主成分输入 BP神经网络进行训练，实现对主成分的预测。最后将主成分预测值与相应的空间模态结合，获取 SSHA 预测值。结果表明，相较于惯性预报和气候态预报，EOF-BPNN 模型不仅能够提供提前 30 天的较为精确的 SSHA 和相应的涡旋演化过程预报，且在整个南海区域拥有更高的 SSHA 相关系数，证明了 EOF-BPNN 模型具有较好的预测性能。 相似文献
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We analyse the lifetimes (persistence) of circulation types using 23 classifications (of which 18 are objective and 5 subjective) in the period 1957–2002 over Europe and its subregions. The objective catalogues are developed on the same gridded climatic data (ECMWF ERA-40 reanalysis) but differ in the classification method used and in the number of synoptic types. Significant seasonal trends in the lifetime (both positive and negative) are fairly scarce and are present in all seasons in the manual catalogues only. In the subjective Hess–Brezowsky catalogue, there is an abrupt shift toward higher persistence in 1986, whereas in the Hungarian manual catalogue, a smaller but significant negative shift took place in the same year. These statistical inconsistencies probably result from inhomogeneities in the subjective catalogues. Our results suggest that the increase in the persistence of circulation types reported recently in several papers for the Hess–Brezowsky catalogue is an artefact rather than a real feature. 相似文献
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Gabriele Bulian 《Ocean Engineering》2010,37(11-12):1007-1026
This paper presents a probabilistic methodology for the analysis of the vulnerability of a ship to the risk of inception of pure loss of stability events. A pure loss of stability failure is modelled as the persistence of the metacentric height below a critical level for a too long time. The metacentric height is modelled as a stationary Gaussian process with a spectrum obtained from the sea elevation spectrum. The time dependent failure index is obtained under the assumption of filtered Poisson process for the occurrence of critical events. The analysis separates cases where the fluctuation of the metacentric height is narrow-band from those where the bandwidth of the spectrum is wide, with an intermediate blending. In case of narrow-band processes appropriate approximate solutions to the problem are provided, while in the wide-band cases an exponential distribution for the persistence time below the critical level is employed. A rational development for the critical persistence time is also provided considering an approximation of the roll dynamics during periods of time where the metacentric height is negative. Monte Carlo simulations are performed to check the developed approximate distributions for the persistence time, and examples of application are provided for a sample ship. 相似文献
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高分辨率遥感图像处理经常面临程序执行时间过长和内存空间不足的问题,虽然并行计算技术可以提高遥感图像的处理速度,但是无法降低算法占用的巨大内存空间。为了解决这一问题,本文提出了一种利用CUDA和内存映射文件的高分辨率遥感图像快速处理方法,并以K-Means算法为例进行了实现。其中,CUDA技术可以有效利用GPU强大的并行计算能力,而内存映射文件技术降低了磁盘I/O速度较慢对算法性能的影响。实验结果表明,本文方法比传统K-Means聚类算法计算速度提高了30倍左右,内存使用量降低了90%以上。 相似文献
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本文从动力学定律出发,推导了一个线性的、具有下垫面温度耦合的大气环流的统计—动力模式,并用该模式对500hPa高度场及1000hPa温度场作1～30天的平均预报试验。模式的预报结果大大优于惯性预报,但耦合与不耦合的结果差别不大。 相似文献