基于多致灾因子相似的热带气旋检索方法研究:以风暴潮-海浪灾害预评估为例

热带气旋引起的风暴潮-海浪灾害成灾频率高、致灾强度大,对我国沿海地区造成的人员和经济损失惨重。预评估阶段需要在灾前对研究区可能造成的损失等进行快速的综合判定。从历史热带气旋中检索出与目标热带气旋位置及各种致灾因子强度相似的热带气旋是快速、准确地预评估风暴潮-海浪灾害的重要方法。面向风暴潮-海浪灾害预评估,提出了一种基于多致灾因子的相似热带气旋检索方法。用于相似检索的致灾因子数据包括:从中国气象局西北太平洋热带气旋最佳路径数据集中提取并经处理得到的1949~2013年影响湛江市的112场热带气旋的路径中心点位置、中心气压、最大风速、最大风速半径及移动速度数据,112场热带气旋的模拟风场、风暴潮及海浪数据。首先,利用相似离度方法对热带气旋进行路径相似性检索;其次,利用最优相似系数方法计算中心气压、最大风速半径、最大风速、移动速度、风场、风暴潮及海浪强度指标的相似系数进行一次检索;然后,根据风场、风暴潮及海浪模拟数据的获取情况,分别基于路径-强度及风场-风暴潮-海浪综合相似性指标进行二次检索;最终给出历史热带气旋的综合相似排序。以2013年尤特热带气旋为例,利用上述方法检索了与其最为相似的5场历史热带气旋。该方法综合考虑了热带气旋路径及多种致灾因子的相似,兼顾了检索的速度及质量,是进行快速、准确的风暴潮-海浪灾害预评估的重要基础。     

1992年福建沿海两个登陆台风灾害的对比分析

本文依据灾情调查材料和台站资料,对路径、强度相似、登陆福建的9216与9215号两个热带气旋灾害,进行对比分析、寻找出两个风暴灾情悬殊的成因,阐明立足于防的减灾体会。     

1984?2017年影响中国热带气旋灾害的时空特征分析

本文基于1984?2017年热带气旋灾情资料和中国气象局上海台风研究所整编的热带气旋最佳路径资料,分析了中国热带气旋灾害的时空特征,比较了不同盛行路径下热带气旋灾害的差异,探讨了盛行路径下热带气旋陆上持续时间变化及灾害潜在风险。结果表明:（1）1984?2017年,直接经济损失呈现上升趋势,但该损失在国民生产总值中占比和死亡人数则呈下降趋势。（2）3类盛行路径热带气旋直接经济损失具有区域性差别。近海转向热带气旋登陆中国的数目少、灾害轻,西行和西北行的热带气旋登陆中国的数目多、范围广、灾害重。其中西行热带气旋主要影响广东、广西和海南,西北行热带气旋主要影响广东、福建和浙江。（3）台风潜在风险影响因子—热带气旋陆上平均持续时间,近几十年来增加趋势显著,但不同盛行路径陆上平均持续时间增加原因不一。近海转向的热带气旋陆上平均持续时间增加与陆上平均移速减小有关,西行和西北行的热带气旋陆上平均持续时间增加主要由陆上平均移动距离增加所致。     

基于HY-2B散射计的热带气旋定位定强研究

热带气旋灾害是最严重的自然灾害之一,其影响程度主要取决于气旋的中心位置和强度。提高热带气旋中心位置及强度监测水平对于改进热带气旋分析预报精度、减少热带气旋的灾害影响具有重要意义。本文以HY-2B散射计为例,分析了散射计风场散度和旋度的分布特征,发现气旋中心附近风场的散度或旋度具有显著的分布规律,由此提出了一种新的气旋中心定位方法,并与传统的直接定位法进行比较研究。在此基础上,进一步提出了热带气旋风圈大小估计的方法,用于评估气旋的强度。最后,利用台风“范斯高”和“博罗依”的遥感数据对文中的方法进行验证,结果表明,使用新方法定位的气旋中心位置与最佳路径之间的差异小于20 km,散射计17 m/s风圈大小的变化一定程度上反映了气旋的发展规律。     

热带气旋资料长度对风暴潮危险性评估结果的影响

热带气旋历史样本数不足一直困扰着风暴潮风险评估研究,本文基于西北太平洋62 a(1949-2010年)历史观测热带气旋事件集资料和用随机模拟方法构造的1000 a模拟热带气旋随机事件集,以福建省连江县为例,开展了资料长度对风暴潮灾害危险性评估结果的影响分析。文中用ADCIRC模型模拟了两种数据集强迫下的风暴潮增水,采用极值Ⅰ型分布法得到了典型重现期的风暴潮增水,经过对计算结果分析发现典型重现期的风暴潮增水计算结果与所用数据资料长度有着密切相关性,数据资料越长,结果越稳定。对于1000 a一遇的风暴潮增水值,使用500 a长度的资料已经趋于稳定,并接近用1000 a资料计算得到的结果。在进行风暴潮危险性评估时,相比用几十年尺度的热带气旋历史数据集,1000 a的热带气旋模拟数据集的计算结果更具实际意义。     

基于层次分析法的惠州市海洋减灾能力评估研究

根据惠州市自然地理条件及地区海洋灾害特点,优化建立了区域减灾能力评估指标体系及评估方法,以惠州市沿海县区大亚湾区及惠东县为研究对象,通过数据收集、评估指标量化对两县区区域海洋减灾能力进行评估.结果 表明:大亚湾区及惠东县区域减灾能力评估等级均为中,评估值大亚湾区高于惠东县9％,一级指标评估结果方面大亚湾区灾害预警报能力...     

西北太平洋热带气旋发源特征与突变初步分析

采用日本气象厅东京台风中心最佳台风路径数据集1977-2011年共35年的资料对西北太平洋热带气旋的发源情况和突变进行了研究分析。结果表明:(1)热带气旋发源地主要集中在两个地方,一个是菲律宾以东海域125-134°E、11°-21°N范围内,另一个是南中国海北部海域111°-119°E、14°-21°N范围内;(2)热带气旋的等级越高,其生成的经度越大,纬度越低;(3)热带气旋生成最多的月份是8月,热带风暴、强热带风暴和台风均以8月份最多,而强台风生成最多的月份是9月,超强台风生成最多的月份则是10月;(4)热带气旋的生命长度、累积气旋能量和功耗指数均与其生成经度成正比,密度峰值均在马绍尔群岛170°E附近;(5)通过对时间序列的热带气旋个数、生命长度、累积气旋能量和功耗指数进行滑动t检验,发现在1995年和1998年均存在突变,从1995年至1998年为热带气旋趋势突变的时间区间。     

热带气旋影响日照地区的统计分析

本文根据所积累的１９８１～１９９７年１７年的资料,对影响日照地区的热带气旋从路径特点,影响时间,灾害特点及程度,以及在沿海造成的风、浪、潮等情况,进行了分类统计;对几个严重影响本地区的台风造成的灾情,也做了较为详细的叙述。     

西北太平洋厄尔尼诺年与拉尼娜年的热带气旋路径对比

台风是一种破坏性极强的自然灾害,我国位于太平洋西岸,是受台风影响最严重的国家之一,因此研究西北太平洋热带气旋路径的分布规律对台风预报有着重要意义。本文利用热带气旋最佳路径数据集资料,研究了1949—2017年间厄尔尼诺年与拉尼娜年发生在西北太平洋的热带气旋的数量及路径分布规律,得出了如下的主要结论：厄尔尼诺年的热带气旋年平均产生数量要少于拉尼娜年,但发展至强度为台风及以上的热带气旋所占比例更高;厄尔尼诺年与拉尼娜年热带气旋路径的分布都主要集中在10～20°N的低纬地区,但厄尔尼诺年的热带气旋路径在菲律宾群岛东侧海域更为集中,拉尼娜年的在菲律宾群岛西侧海域更为集中;强度为台风及以上的热带气旋路径分布规律与所有强度热带气旋路径的分布规律相似,但更偏北一些,尤其在厄尔尼诺年偏北现象更为明显;热带气旋增强区域的分布与热带气旋路径的分布规律基本相同。     

热带气旋在东海的活动及其灾害分析

本文根据1949～1989年热带气旋历史资料,对影响东海的热带气旋进行了统计分析,结果表明,热带气旋在东海的活动相当频繁,特别是7、8、9三个月;热带气旋逐年出现个数有明显的年际波动和季节性变化;进入东海的热带气旋大致分为七类路径,不同路径的热带气旋对东海沿岸地区造成不同程度的危害,其灾情以具体实例作了阐述。     

Microbial Biomass and Organic Nutrients in the Deep-Sea Sediments of the Central Indian Ocean Basin

In order to assess the impact of deep-sea mining on the in situ benthic life, we measured the microbial standing stock and concentration of organic nutrients in the deep-sea sediments of the Central Indian Ocean Basin in the Indian pioneer area. Sediments were collected using box core and grab samples during September 1996. The total bacterial numbers ranged from 10 10 -10 11 cells per g -1 dry weight sediment. There was a marginal decrease in the number of bacteria from surface to 30 cm depth, though the subsurface section registered a higher number than did the surface. The highest numbers were encountered at depths of 4-8 cm. The retrievable number of bacteria were two orders less in comparison with the direct total counts of bacteria. An almost homogeneous distribution of bacteria, total organic carbon, living biomass, and lipids throughout the depth of cores indicates active microbial and benthic processes in the deep sea sediments. On the other hand, a uniform distribution of total counts of bacteria, carbohydrates, and total organic carbon in all the cores indicates their stable nature and suggests that they can serve as useful parameters for long-term monitoring of the area after the benthic disturbance. Further studies on temporal variability in this region would not only verify the observed norms of distribution of these variables but would also help to understand restabilization processes after the simulated benthic disturbance.     

海上大直径钢管桩打桩过程中桩周土强度弱化研究

海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明：土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。     

Geoacoustic Inversion via Genetic Algorithm and Its Application to Manganese Sediment Identification

An acoustic inversion method using a wide-band signal and two near field receivers is proposed and applied to multiple layered seabed models including a manganese sediment. The inversion problem can be formulated into a probabilistic model comprised of signals, a forward model, and additive noise. The forward model simulates wide-band signals, such as chirp signals, and is chosen to be the source-waveletconvolution plane wave modeling method. The wavelet matching technique, using weighted least-squares fitting, estimates the sediment sound-speed and thickness on which determination of the possible numerical ranges for a priori uniform distribution is based. The genetic algorithm is applied to a global optimization problem to find a maximum a posteriori solution for determined a priori search space. Here the object function is defined by an L 2 norm of the difference between measured and modeled signals. Not only the marginal pdf but also its statistics are calculated by numerical evaluation of integrals using the samples selected during importance sampling process of the genetic algorithm.     

A Review of Some Environmental Issues Affecting Marine Mining

This article reviews information recently available from existing marine and coastal mining for responses to environmental issues affecting marine mining at different depths. It is particularly but not exclusively concerned with those issues affecting seabed biodiversity impact and recovery. Much information has been gathered in the past 10 years from shallow mining operations for construction aggregate, diamonds, and gold, from coastal mines discharging tailings to shallow and deep water, and from experimental deep mining tests. The responses to issues identified are summarized in a series of eight tables intended to facilitate site-specific consideration. Since impacts can spread widely in the surface mixing layer SML, and can affect the biologically productive euphotic zone, the main issues considered arise from the depth of mining relative to the SML of the sea. Where mining is below the SML, the issue is whether it is environmentally better to bring the extraction products to the surface vessel for processing (and waste discharge), or to process the extraction products as much as possible on the seabed. Responses to the issues need to be sitespecific, and dependent on adequate preoperational environmental impact and recovery prediction. For deep tailings disposal from a surface vessel, there are four important environmental unknowns: (1) the possible growth of "marine snow" (bacterial flocs) utilizing the enormous quantities of fine tailings particles (hundreds or thousands of metric tons per day) as nuclei for growth, (2) the possibility that local keystone plankton and nekton species may migrate diurnally down to and beyond the depth of deep discharge and hence be subjected to tailings impact at depth, (3) the burrow-up capability of deep benthos and their ability to survive high rates of tailings deposition, and (4) the pattern and rate of dispersion of a tailings density current through the deep water column from discharge point to seabed. Actions to obtain relevant information in general and site-specifically are suggested.     

Increased Particle Fluxes at the INDEX Site Attributable to Simulated Benthic Disturbance

Particle fluxes were measured 7 m above the sea bottom during the predisturbance, disturbance, and postdisturbance periods by using time series sediment traps attached to seven deep-sea moorings deployed in the INDEX experiment site in the Central Indian Basin. The predisturbance particle fluxes varied between 22.3 to 55.1 mg m -2 day -1 . Increased and variable particle fluxes were recorded by the sediment traps during the disturbance period. The increase observed was 0.5 to 4 times more than the background predisturbance fluxes. The increases in particle fluxes (~4 times) recorded by the sediment trap located in the southwestern direction (DMS-1) were the greatest, which could be the result of preferential movement of resuspended particles generated during the deep-sea benthic disturbance along the general current direction prevailing in this area during the experimental period. Also, the traps located closer to the disturbance area recorded greater fluxes than did the traps far away, across the Deep Sea Sediment Resuspension System path. This variability in recorded particle fluxes by the traps around the disturbance area clearly indicates that physical characteristics such as grain size and density of the resuspended particles produced during the disturbance had an important effect on particle movement. The postdisturbance measurements during ~5 days showed a reduction in particle fluxes of ~50%, indicating rapid particle settlement.     

Phylogenetic diversity and phenotypic characterization of cultivable bacterioplankton isolated from polar oceans

A set of 27 marine planktonic bacteria isolated from the polar regions was characterized by 16S rDNA sequencing and physiological and biochemical testing. More than half of these bacteria were positive for caseinase, gelatinase and 13-glucosidase, and could utilize glucose, maltose or malic acid as carbon source for cell growth. Twelve isolates expressed nitrate reduction activities. Except for one antarctic isolate BSwlO175 belonging to Actinobacteria phylum, these isolates were classified as γ-Proteobacteria, suggesting that γ-Proteobacteria dominated in cultivable marine bacterioplankton at both poles. Genus Pseudoalteromonas was the predominant group in the Chukchi Sea and the Bering Sea, and genus ShewaneUa dominated in cultivable bacterioplankton in the Prydz Bay. With sequence similarities above 97%, genus Psychrobacter was found at both poles. These 27 isolates were psychrotolerant, and significant 16S rDNA sequence similarities were found not only between arctic and antarctic marine bacteria （ 〉 99% ）, but also between polar marine bacteria and bacteria from other aquatic environments （ ≥ 98.8% ）, including temperate ocean, deep sea, pond and lake, suggesting that in the polar oceans less temperature-sensitive bacteria may be cosmopolitan and have a bipolar, even global, distribution at the species level.     

Determination of In Situ Sediment Shear Strength from Advanced Piston Corer Pullout Forces

The advanced piston corer (APC) has been used by the Ocean Drilling Program since 1985 for recovering soft sediments from the ocean floor. The pullout force measured on extracting the core barrel from the sediment is shown to correlate with the average shear strength of the sediment core measured in the ship's laboratory. A simple rule of thumb is derived relating the shear strength of the sediment to the pullout force. Multiple APC holes at individual sites allow the consistency of the pullout measurements to be assessed. The effects of different operational procedures during APC coring are also explored. Although generally applicable, the correlation between pullout force and laboratory measurements of shear strength breaks down for some APC holes, possibly because of the disturbance of some sediment types during the APC coring process. A better understanding of the physical process of APC coring, and its effect on the properties of the sediment both inside and immediately outside the core barrel, would indicate what confidence can be put on the measurement of pullout force as a way of evaluating the in situ shear strength of deep sea sediments.     

Deep-Sea Sediment Compression Curves: Some Controlling Factors, Spurious Overconsolidation, Predictions, and Geophysical Reproduction

Oedometer tests have been carried out on 70 undisturbed surficial clays (at approximately 250 mm below the mudline), mostly collected by free-fall corers from sites widely scattered throughout the deep-sea North Atlantic. Acoustic measurements were also made, initially on contiguous samples and ultimately on the same sample using a geophysically instrumented oedometer which also collected electrical resistivity data. Apart from those quiescent areas below the carbonate compensation depth, such as north of the West Indies where very fine clays exist, most of the samples are silty clays whose geotechnical-geophysical properties are dependent on the type of clay minerals present (and their ability to take in moisture), the sand-size fraction, and the quantity of carbonate present. Thus the pure clays have high compressibilities which decrease on the addition of coarse particles, while the converse is true for the acoustic parameters, these increasing with the sand fraction. Using the notion of the intrinsic compression line for all samples, and comparison to it of the measured compression curves, it is clear that, contrary to some previously held ideas, most deep-sea clays are normally consolidated; the addition of carbonate has the effect of creating an open, stronger sediment skeleton. Interestingly, where information is available, the variation with depth of a sample's acoustic velocity follows the void ratio pressure relationship of the compression curve. This allows the construction of an in-situ sediment compression curve using the in-situ geophysical observations.