Cyclone induced storm surge and flood forecasting in the northern Bay of Bengal     

《Coastal Engineering》2004,51(4):277-296

A cyclone induced storm surge and flood forecasting system that has been developed for the northern Bay of Bengal is presented. The developed system includes a cyclone forecasting model that uses statistical models for forecasting of the cyclone track and maximum wind speed, and an analytical cyclone model for generation of cyclone wind and pressure fields. A data assimilation system has been developed that allows updating of the cyclone parameters based on air pressure and wind speed observations from surface meteorological stations. The forecasted air pressure and wind fields are used as input in a 2D hydrodynamic model for forecasting storm surge levels and associated flooding. An efficient uncertainty prediction procedure based on Harr's point estimation method has been implemented as part of the forecasting system for prediction of the uncertainties of the forecasted storm surge levels and inundation areas caused by the uncertainties in the cyclone track and wind speed forecasts. The developed system is applied on a severe cyclone that hit Bangladesh in April 1991. The simulated storm surge and associated flooding are highly sensitive to the cyclone data. The cyclone data assimilation system provides a more accurate cyclone track when the cyclone approaches the coastline, which results in a significant improvement of the storm surge and flood predictions. Application of the uncertainty prediction procedure shows that the large uncertainties of the cyclone track and intensity forecasts result in large uncertainties of the forecasted storm surge levels and flood extend. The forecasting system shows very good forecasting capabilities up to 24 h before the actual landfall.  相似文献   

全新世海侵对长江口沿海平原新石器遗址分布的影响   总被引：17，自引：11，他引：6  

王张华  陈杰 《第四纪研究》2004,24(5):537-545

文章通过对长江三角洲南北两岸太湖和里下河两大平原新石器遗址分布和迁移特征的对比研究,发现两地新石器文化均起源于7000aB.P.前。可以认为全新世气候变暖和海平面上升是两地新石器文化兴起的原因。之后里下河平原经历了由全新世海侵引起的盐沼化过程,古文化发展受到明显的抑制;相比之下,太湖古平原为一丘状台地,地势高爽,加上贝壳砂堤对海水的有效阻挡,盐沼化过程稍弱,古文化得以延续和繁荣。  相似文献   

筛析法分析砂砾质样品的取样质量估算——对现行国标有关规定的扩展讨论     

宗羿冰  陈奇  朱永兰  唐雯雯  蔡廷禄  贾建军 《海洋与湖沼》2024,55(2):386-396

筛析法是硬件要求低、操作简便、应用广泛的一种碎屑沉积物粒度分析方法。对于砂砾质沉积物而言,在具体的粒度分析实验中,应该取用多少质量的样品进行筛析,目前尚缺乏完备的、科学内涵明确的技术规范。《海洋调查规范第8部分:海洋地质地球物理调查》对此问题给出了部分解决方案,但其原理不明,也未能包括砂砾质沉积物的主要粒径范围。本研究针对筛析法取样质量的估算问题展开分析与讨论,基于概率分布理论推导出一套适用于砂砾质样品的筛析法取样质量估算公式,给出了不同分选系数下(0.35Φ～4.00Φ)样品最大颗粒直径对应的理论取样最小量的范围。研究表明,现行海洋调查规范的最大颗粒直径与取样最小量之间的定量关系可能是基于正态分布、分选极差的下界(σ=4.00Φ)的情况推算而来的;可将筛析法取样质量估算表的最大颗粒直径扩展至64 mm,该粒径对应的理论取样最小量为47.8 kg。为了检验推导的公式,以浙江省舟山群岛和象山半岛的潮间带近200个砂砾质样品为例,计算了样品最大颗粒直径对应的筛析法理论取样最小量及其理想状态下的正态粒度分布,并与实际样品的取样量及粒度分布分析结果进行了对比。结果显示,大部分样品的粒度分析结果...  相似文献   

Temporal distribution of trace metals in Antarctic coastal waters     

《Marine Chemistry》2001,76(3):189-209

  相似文献   

Coupling iodine speciation to primary,regenerated or “new” production: a re-evaluation     

《Deep Sea Research Part I: Oceanographic Research Papers》2001,48(6):1459-1476

In two recent studies (Tian et al., Deep-Sea Res. I 43 (1996) 723–738; Campos et al., Deep-Sea Res. II 43 (1996) 455–466), in order to explain the observed temporal variations in the distributions of the dissolved iodine species at the time-series stations in the Mediterranean Sea, the North Atlantic and the North Pacific, diverse assumptions were invoked on the relationships between changes in the speciation of dissolved iodine in the surface oceans and biological production such that the surface enrichment of I⁻ was linked to both regenerated production and primary production while the surface depletion of [IO₃⁻+I⁻] was linked to “new” production. However, while some of the major conclusions in these studies are critically dependent on these assumptions, the validity of the assumptions has yet to be verified with experimental evidence. On the other hand, while there are still significant unknowns in the understanding of the cycling among dissolved iodine species in the surface oceans, presently available data from laboratory cultures and field observations are consistent with an alternative conceptual model in which IO₃⁻ and NO₃⁻ are taken up at some ratio to each other during NO₃⁻ uptake and almost all of the IO₃⁻ taken up is exuded as I⁻. Thus, the depletion of IO₃⁻ and the enrichment of I⁻ in the surface water are linked to NO₃⁻ uptake. This alternative model is also consistent with the data sets presented by Tian et al. (1996) and Campos et al. (1996). By linking the surface depletion of IO₃⁻ to NO₃⁻ uptake, significantly different biogeochemical behavior of the marine dissolved iodine system may be inferred. The extent to which I⁻ may be oxidized to IO₃⁻ within the euphotic zone during the residence time of the water in the surface ocean is still an open question.  相似文献   

地质断层三维构模技术研究   总被引：2，自引：0，他引：2  

朱良峰  潘信 《岩土力学》2008,29(1):274-278

对包含断层的复杂地质体三维构模技术展开讨论并提出相应的解决方案。分析了实际勘察所获取的断层数据类型,设计了标准的断层数据库格式;系统地评价了两类基本的断层构模方法（即基于地层恢复的断层构模技术和基于分区插值的断层构模技术）,分析了各自的特点和不足,在此基础上提出了断层与地层的统一构模技术;该技术既能应用于同沉积断层,又能适应断层终止于地层内部的情况,还能处理具有多值面的逆断层构造的拟合问题,在理论上能够构造任意复杂的断层系统。通过北京奥运公园场址的断层构模实例验证了该方法的有效性。  相似文献   

Magnetic indicator of global paleoclimate cycles in Siberian loess–paleosol sequences     

Vadim A. Kravchinsky  Valentina S. Zykina  Vladimir S. Zykin 《Earth and Planetary Science Letters》2008,265(3-4):498-514

The loess–paleosol sequences of China, Siberia, Alaska and many other regions, along with lake sediments and glaciers, provide the only accurate paleoclimatic terrestrial records for intervals of thousands to hundreds of thousand years. The frequency dependence (FD) of magnetic susceptibility (MS) in such sequences has become the leading parameter for analyzing climatic change and Milankovitch (astronomical) periodicity in Siberian sequences; it is always higher in soil horizons than in loess. The enhanced FD parameter in soils is associated with ferromagnetic minerals, mostly magnetite, produced during pedogenesis. The MS and FD parameters of 670 samples from five sections in Siberia are reported here. Inter-section correlation is used to produce a combined FD time series for the studied sections. Chronological control is established by absolute dating and stratigraphic correlation. Spectral analysis of the FD time series reveals the presence of Milankovitch signals at ～100 kyr (eccentricity), ～40 kyr (obliquity) and ～23 kyr (precession) and demonstrates that Siberian loess–paleosol sequences are excellent continental recorders of long-term paleoclimatic changes. This suggests that the FD parameter can potentially be used more widely for evaluation of climate periodicity in loess/paleosol sequences in other parts of the world.  相似文献   

社区居住环境的空间数据探索性分析   总被引：3，自引：3，他引：0  

艾彬  徐建华  黎夏  卓莉 《地理科学》2008,28(1):51-58

社区作为城市内部空间尺度单元之一,作为人类的活动中心,居住环境备受人们关注,因此对其进行定量分析是目前城市研究的热点之一。采用GIS、空间数据探索性分析和网格计算相结合的方法,选取上海市外环以内131个街镇社区作为研究对象,对其内部居住环境的空间格局进行探索性分析研究。通过研究发现,社区居住环境是不同因子相互联系、相互作用的结果,其在空间上的分布相应地表现出局部的差异性和整体上的趋同性。并从空间联系的角度出发,提出了对研究区各个社区在空间上布局和规划的方案。  相似文献   

上海与长江流域各省区间的旅游互动   总被引：16，自引：3，他引：13  

汪宇明  高元衡 《地理学报》2008,63(6):657-668

采用转移-份额分析法对1999-2005 年上海及长江干流区域内各省区入境旅游者统计 数据和抽样调查数据进行分析研究发现, 在长江流域各省区出、入沪旅游流总量增长中, 结 构性转移分量的贡献影响发挥着主导影响; 份额分量的贡献影响发挥着基础性影响作用; 而 竞争性转移分量的贡献影响虽然有表现, 但其作用绩效明显低于其他分量的影响绩效; 总体 上, 结构性转移分量与份额分量高度集聚于上海毗邻的江浙地区, 表现出长三角地区旅游流 的高度内聚性; 但出、入沪旅游流增量中的各分量贡献影响, 在长江流域各省区间出现显著 的不均衡现象, 上海出沪旅游辐射强度在长江流域自东向西呈现出“U”型格局的空间变化。 其中, 距离尺度虽然是影响旅游流空间差异变化的重要因子, 但省区间的资源禀赋、旅游区 位交通的便捷性、旅游产品特色与供给结构变动、区域间旅游一体化程度等因子所构成的区 域性差异, 则是影响大都市与区域间旅游互动程度和空间格局的深层次原因。促进大都市与 不同尺度规模区域之间的旅游互动, 实现大都市与区域间旅游和谐发展, 全面提升中国旅游 的空间效益, 是中国区域旅游深度发展需要进一步关注的战略性命题。  相似文献   

上海市人类活动对热环境的影响   总被引：13，自引：1，他引：12  

岳文泽  徐建华 《地理学报》2008,63(3):247-256

随着城市规模不断扩张, 由城市热岛现象而导致的热环境问题不断凸现。城市热环境 的时空变化, 是下垫面改变、人为热释放和环境污染等人类活动因素相互交织作用的结果。 由于城市热环境影响因子的复杂性, 传统观测手段和统计方法在获取数据和分析人类活动对 热环境响应机制方面存在着局限性。而卫星遥感和GIS 技术为人类活动对城市热环境的影响 分析提供了技术支撑。选用Landsat ETM+ 影像, 以上海市外环内区域为研究靶区, 在探讨热 环境的空间格局基础上, 运用空间主成分分析方法替代传统的多准则判断(MCE) 方法, 分析 了人类活动对城市热环境的影响特征。结果发现, 对于上海主城区而言, 城市建筑与人口密 度、工业区布局、下垫面类型以及城市景观多样性四个因子是影响城市热环境空间格局的主 导因子; 四个因子的线性模型, 较好地模拟了热环境的空间变化, 定量揭示了上海城市人类活动对热环境的影响机制。  相似文献