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波面极大值处水质点水平速度的统计分布 总被引：1，自引：0，他引：1
管长龙 《中国海洋大学学报(自然科学版)》1998,(1)
基于Ｌｏｎｇｕｅｔ－Ｈｉｇｇｉｎｓ提出的线性随机海浪模型,导出了波面极大值处水质点水平速度的统计分布。分布的形式类似于波面极大值的统计分布,其中引入了一个新的谱宽度参量εｕ为１－ｍ２３ｍ２ｍ４１２。当εｕ趋于零时,导出的分布函数为瑞利分布;当εｕ趋于１时,则为正态分布。在窄谱情形下εｕ趋于１２ε,其中ε为１－ｍ２２ｍ０ｍ４１２,为常用的谱宽度参量 相似文献
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基于海浪谱估计理论，按谱估计方法导出了离散波面记录平滑处理后的谱形式，并计算了由各阶谱矩表示的谱宽度。指出平滑后的离散波面记录产生了新的随机过程，它们和原离散波面记录的内部结构和外部特征是完全不同的。但高阶矩表示的无因次谱宽度，即ε5=√1-m5^2/m4m6,ε7=√1-m7^2/m6m8几乎不受平滑（N=2，N=3）的影响，和原始谱的对应值相吻合。通过离散波面记录求导处理得波面速度谱，与理论转换得速度谱结果几乎完全一致。 相似文献
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用波面高度分布的非正态特征反演非线性随机海浪 总被引：1，自引：0，他引：1
本文不依据波动的非线性方程,而是利用波面高度分布的非正态特征反演非线性随机海浪.在窄谱条件下,论述了反演的非线性波面、谱及波面极大(小)值分布同现有某些非线性理论结果的一致性,以深水正态海浪过程用浅水非正态特征反演浅水非线性海浪过程及其谱作为算例,并用实测资料检验,结果表明,其同实测值符合较好,从而说明本文方法是可行的. 相似文献
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变浅作用下浅水海浪谱的计算 总被引：1，自引：0，他引：1
深水海浪向近岸传播过程中,由于变浅作用,其波面高度分布,波谱都发生了变化。本文基于非线性系统的输出和输入间亦存在转换关系,通过波面高度分布函数建立了深水正态海浪过程作为输入和浅水偏态海浪过程作为输出之间的非线性转换关系,导出了深、浅水谱间的理论关系。在假定能通量不变的条件下,提出了一种由已知深水谱和波面偏度计算二维海浪变浅作用下的浅水谱的方法,并对其进行了讨论和检验。 相似文献
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利用大型水槽设计了在由深水到近岸不同坡度处海浪在变浅作用下诱导产生的长周期重力波的实验。正态随机海浪在深水生成并沿斜坡向浅水传播,记录了不同水深处波面高度随时间的变化过程并进行统计分析和谱分析。实验数据分析结果表明,长周期重力波的能量随着水深的变浅而增高,其谱锋频率位于0.2~0.3fp附近,这里fp是深水正态海浪过程的谱峰频率。长周期重力波的能量与入射波的能量比与波面高度分布的偏度密切相关。进一步分析了两种波动的能量谱峰值比和波面高度分布偏度的相关关系,获得了经验关系,为预测近岸浅水长周期重力波提供了科学依据。 相似文献
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通过分析实验室风浪观测结果研究非线性效应对波面极大值和极小值分布的影响。波面极大值和极小值累积概率的差异表明 ,与线性理论相比 ,波面极小值在平均波面以下的位置偏高。对实验结果的进一步分析表明 ,非线性效应使波面极大值在平均波面以上总概率高于线性理论结果 ,而概率密度峰值处波面极大值高度略低于线性理论结果。波面极小值在平均波面以上各位置出现的概率均高于线性理论结果 ,在平均波面以下的较低位置 ,波面极小值出现概率明显低于线性理论结果。 相似文献
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风浪波高和周期的联合概率密度分布 总被引：1，自引：0，他引：1
本文采用有代表性的44008美国国家浮标站2003年1～3月实测的海浪谱密度资料,选取三次大风过程进行风浪谱分析。通过对实测平均海浪谱与PM谱、JONSWAP谱及Torsethaugen谱的比较,得到PM谱拟和最好。然后用国际上最先进的随机波分析方法,根据协方差矩阵的循环嵌套技术,以实测平均谱与PM谱为靶谱,对随机波面进行模拟。得到由模拟波面统计的特征值及估计的谱与实测谱结果极为相近,谱峰及谱峰频率都基本一致。说明利用模拟波面研究海浪具有代表性,它可以反映实测海浪的特征。利用Longuet-Higgins(1983)模型计算波高-周期联合概率密度分布,得到变换高斯过程计算的波高、周期联合分布与实测情况基本相同,更好地描述了波高-周期联合概率密度分布。 相似文献
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基于非线性Beta波面分布,采用经验变换,导出1种仅用随机波面偏度λ3和尖度λ4 2个参数表示的非线性海浪波高概率统计分布--波高类Beta分布.此分布发展了线性窄谱假定下的Rayleigh分布.就所用实验室资料验证而言,本文推导的波高类Beta分布要优于几种工程上常用的波高分布. 相似文献
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One hundred and seven marine aerosol samples were collected during December 1988 to March 1990, and 3 dry deposition samples, 16 rain samples and 2 Cascade Impacter samples were collected from March to May 1990 at the southeast coast of the Xiamen Island. All the samples were analyzed for SO42-, NO3-, Cl-, Na+ , NH4+, using ion chromatography.The results indicate that the concentration of sulfate in marine aerosols over the Xiamen waters appears to be of seasonal variation, in an order of winter > spring > autumn > summer. The mean sulfate concentration lor the total marine aerosol samples over the Xiamen waters is 9. 37 μg/m3, respectively 0. 89 and 8. 48 μg/m3 for the seasalt and non-sea-salt sulfate. The distribution of sulfate shows a bimodal form with a peak in the coarse particle range which is derived from the sea-salt sulfate, and a peak in the fine particle range which is derived from the non-sea-salt sulfate. The total deposition of sulfate to the Xiamen waters is estimated to be 4. 68g/m2 相似文献
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Abstract. The distribution of the thalassinidean shrimp Upogebia pusilla was studied at four sites in the North Adriatic Sea: 1) a tidal flat in the lagoon of Grado, 2) a tidal flat at Lido di Staranzano near the mouth of the Isonzo, 3) a mud flat seawards of a salt marsh in a protected bay north of Rovinj, and 4) a sublittoral station in 6m depth near Aurisina. Information on grain size distribution, organic content, amount of debris, redox profiles and pH of sediment as well as temperature and salinity is given. Density, as determined by hole counts and a hole: burrow relationship derived from resin casting, generally increased with increasing water depth in the intertidal. The upper limits ranged between +10cm (Rovinj) and -20cm (Grado); densities between mean water and low water level varied strongly due to microtopography and macrophyte cover. Maximum densities in the intertidal ranged from 189 (Grado) to 2420 (Rovinj, juveniles) animals m2 . Shrimp density at the sublittoral station ranged between 80 and 230 m"2 . The zonation of the Upogebiidae and Callianassidae with respect to environmental parameters is discussed. 相似文献
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The statistical distribution of wave orbital velocity in intermediate coastal water depth has been quantitatively determined from the comprehensive field velocity data collected near the seabed in this study. Two ocean ADV current meters, which were mounted at 0.5 m above the seabed on two separate stainless steel tripods sitting on the seabed, were used to measure instantaneous water particle velocities at a 2 Hz sampling rate for 17.07 min every hour in two coastal water depths of 11 m and 23 m in nine field deployments over a period of 2 years. The zero-crossing method is applied to analyse the field velocity data collected in each field deployment to obtain a large sample of wave orbital velocity amplitudes of individual waves. Based on the collected field velocity data, it is found that the histogram of instantaneous wave orbital velocities perfectly follows the Gaussian distribution as commonly assumed, while the histogram of wave orbital velocity amplitudes is less accurately described by the Rayleigh distribution than the modified Rayleigh and the Weibull distribution. It is also found that large orbital velocity amplitudes are generally overestimated by the Rayleigh distribution, but well predicted by the modified Rayleigh and the Weibull distribution. The expected value of maximum orbital velocity in a velocity record of finite size is also derived from the three distributions and found to agree well with the present field data. 相似文献
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为了解南麂列岛国家海洋自然保护区岩礁相潮间带多毛类的生态现状和功能,于2012年5月（春季）、8月（夏季）、11月（秋季）和2013年2月（冬季）在保护区内进行了四次底栖生物调查,对采集的多毛类样品进行鉴定,并依此计算丰度、生物量和相关生物多样性指数。四季共采集到多毛类85种,春季多毛类平均丰度和平均生物量分别为492 ind/m2和39.50 g/m2,夏季为895 ind/m2和20.95 g/m2,秋季为639 ind/m2和16.51 g/m2,冬季为511 ind/m2和9.04 g/m2。各断面的物种多样性指数变化范围为2.950-4.864,均匀度指数为0.922-0.990,种类丰富度指数为2.486-7.087。最后通过分析发现,潮汐、季节变化和人类活动等因素不同程度地影响了多毛类在岩相潮间带的空间分布及群落特征。 相似文献
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By using a new concept of the discrete amplitude, we examine the statistical properties of narrow-banded random waves. The main results are as follows: (1) the wave height distribution follows the Rayleigh distribution in the case of an infinitely narrow-banded spectrum in the strict sense; (2) the discrete amplitudes, different from the crest heights, are distributed according to the Rayleigh distribution for arbitrary bandwidth spectra; (3) the statistical distribution of the gap length between the discrete amplitude and the crest is examined and derived theoretically. The derived distribution agrees well with the result of numerical simulations; (4) taking into account the gap length distribution, the probability density function of crest heights is derived, which deviates from the Rayleigh distribution. 相似文献
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东山岛近岸水域厦门文昌鱼浮游幼体的分布 总被引：5，自引：2，他引：5
通过1990年5、8、11月和1991年1月的调查发现，东山岛近岸的厦门文昌鱼（Branchiostomabelcheri）浮游幼体，主要分布在该岛的东部和南部水域。其数量相当多，基本上集中出现在春末（5月）和夏季（8月），平均密度分别为24．4尾／m3（或402．73尾／m2）和232．2尾／m3（2．394×103尾／m2），最大密度（8月下旬）达888尾／m3（1．332×104尾／m2）。体长组成表明，该水域的厦门文昌鱼为分批产卵繁殖。幼体生长发育到体长5mm左右时，身体的形态结构与成体基本相同，并开始陆续转为潜沙生活。 相似文献
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《Marine and Petroleum Geology》2003,20(6-8):823-849
Quantifying the characteristics of the turbidity currents that are responsible for the erosion, lateral migration and filling of submarine channels maybe useful for predicting the distribution of lithofacies in channel fill and levee reservoirs. This paper uses data from a well-studied submarine channel in Amazon Fan in an attempt to reconstruct the velocity, thickness, concentration, duration, recurrence rates and vertical structure of turbidity currents in this long sinuous channel. Estimates of flow conditions are derived from the morphology of the channels and the characteristics of the deposits within them. In particular, the availability of information on the sediment distribution with respect to the channel topography at the time of deposition allows for insights into the vertical structure of the flow, a key property that has been so far poorly understood. Integration of flow constraints from well and seismic data or from detailed analysis of outcrop with numerical flow models is a critical step toward a complete understanding of the flow and associated deposits. Turbidity currents in sinuous submarine channels, exemplified by Amazon Channel, are found to last for tens of hours and occur on a regular, quasi-annual basis. Model results suggest that these flows had, on average, velocities ranging from 2 to 4 m/s in the canyon/upper fan which decreased to 0.5–1 m/s in the lower fan, travelling in excess of 800 km. The model turbidity currents were subcritical over most of the channel length, indicating a low degree of water entrainment and low rate of deceleration down the channel. The formation of such long, sinuous channels is intrinsically associated with frequent, long-duration, subcritical turbidity currents carrying a silt-dominated sediment load. 相似文献
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渔山列岛潮间带底栖海藻生态的初步研究 总被引：7，自引：0，他引：7
本文根据１９８７年１１月至１９８９年５月渔山列岛（２８°５３′Ｎ，１２２°１６′Ｅ）潮间带底栖海藻调查资料，分析了该海区潮间带的海藻种类、垂直分布及生物量的季节变化规律，并将本区海藻生态特点与临近海区作了比较。 相似文献