Assimilating temperature and salinity profile observations using an anisotropic recursive filter in a coastal ocean model

In order to improve the ocean forecasting in the North Sea and Baltic Sea, an assimilation scheme based on a bottom-topography-dependent anisotropic recursive filter has been used in this study. This scheme can stretch or flatten the shape of a local representative contour surface of the background error covariance function into the form of an ellipse. Furthermore, the computing efficiency has been largely improved due to implicit computation of the background error covariance. A two-month experiment has been used for verifying the impact of assimilating ocean profile observations on ocean forecasting. The results indicate that the use of temperature and salinity profiles can largely improve the oceanic forecasting. The root mean square differences between the forecasts and observations for temperature and salinity have been reduced by 36% and 18% in the experiment period, respectively. Moreover, it is found that the anisotropic recursive filter approach is especially efficient in areas with complex coastlines and sharp fronts, e.g., inner Danish waters. The results also show that the propagation of observation information from an observation position to its neighboring grid points is closely related to currents.     

美国水雷作战能力现状与发展研究

从水雷装备和布雷能力 2 个方面介绍了美国水雷作战能力现状。重点介绍了近年来美国开展的水雷改进/研制项目和布雷能力建设情况,包括“快速打击”系列水雷、隐蔽投送水雷、先进水下武器系列、 “锤头”水雷,以及无人布雷平台等。总结了未来美国水雷作战能力,分析了美国水雷作战能力发展的特点, 提出了美国水雷发展对我们的启示。     

Experimental study of three-dimensional breaking wave kinematics

Particle image velocimetry has been used to examine three-dimensional breaking wave kinematics. Two cases of wave breaking were studied. In the first case, the wave field contains a single frequency with a uniform angular spreading within a given range {{ — , .}}. The wave field of the second case consists of a number of frequencies with a uniform angular spreading applied to each frequency. In both cases, the waves are designed such that the wave energy is focused at a given point. The degree of angular spreading has been found to have great effects on the breaking characteristics and kinematics. Two types of breaker were observed, the first being plunging and the second being spilling. Increasing the angular spreading had the effect of making the velocities within the extreme waves larger. The ratio of the crest velocity to the breaking wave speed was approximately unity under both single and multiple frequency conditions, regardless of the angular spreading.     

U–Pb Ages for Zircon Grains from Nsanaragati Alluvial Gem Placers: Its Correlation to the Source Rocks

The Mamfe Basin is located in the SW of Cameroon and is an extension of the much bigger Benue Trough in the SE of Nigeria. Along the Asenem River and its tributaries in the western part of the Mamfe Basin (close to the border with Nigeria) gem placers yielding big zircon grains were found in recent river sediments close to Nsanaragati. In order to determine the source area and to establish a possible correlation between the zircons found in the Nsanaragati placers and rocks surrounding the Mamfe Basin 56 detrital zircon grains were analysed regarding their U–Pb ages and selected trace element contents by LA‐ICP–MS techniques. Possible source areas are rocks from the Benue Trough in the West and from the Cameroon Volcanic Line (CVL) in the SE of the study area. Based on microscopic analyses it was possible to distinguish two groups of zircons: reddish and non‐reddish ones, where the latter group comprises color variations from brown to orange, yellow to even colorless. In general, the detrital zircons show high hafnium values (4576 to 12565 ppm) and very variable thorium (7.8 to 1565 ppm) and uranium values (13.4 to 687 ppm). The Th/U ratios vary from 0.4 to 2.3, allowing correlations for some zircon grains to kimberlitic, granitic or syenitic affinities. It was also possible to distinguish zircon grains crystallised in mafic mantle‐derived melts from those crystallised in felsic melts, e.g. from continental rift‐related magmatic systems. In general, the U–Pb zircon ages obtained range from 11.7 to 1949 Ma. All zircons of the reddish group yielded almost similar ages resulting in a Concordia age of 12.4 Ma (Serravallian), an age unknown from the Mamfe Basin so far. The group of non‐reddish zircons showed various ages ranging from Serravallian to Orosirian. It was possible to correlate the youngest ages with rocks known from intrusions along the CVL, dated with K/Ar or Ar/Ar methods. The most probable sources were Mount Bamenda and Mount Bambouto in the east of the Mamfe Basin. Cretaceous ages are interpreted as re‐recycled clastic sediments whose original source had been rocks in the south and the north of the Benue Trough and who had been eroded and deposited within the catchment area of the Asenem river system in the Mamfe Basin in post‐Cretaceous times. The oldest ages are assumed to represent the pan‐African and pre‐pan‐African basement of the Mamfe basin.     

多金属结核样品中微量碘的测定

试验了艾斯卡试剂半熔温度对离子色谱法测定多金属结核中碘的影响，选定半熔温度为６７０℃可控制锰酸盐的形成以消除其对测碘的干扰。用此法测定多金属结核标样中碘，其结果与信息值符合，９次测定的ＲＳＤ小于２５％，加标回收率在９５５％～９７％。     

焉耆盆地侏罗系油气成藏期次分析

着重用油藏地球化学分析方法探讨了焉耆盆地侏罗系油气藏的成藏时间和期次。油源对比表明八道湾组是主力烃源岩层，三叠系烃源岩对八道湾组原油有一定贡献；油气经短距离的侧向运移后，沿断层通道向上进入三工河组和西山窑组。盆地经历了2次生烃，侏罗纪末期为主要生烃期，第三纪晚期为次要生烃期。储层流体包裹体分布特征、均一温度和组分特征、储层自生伊利石测年和油气成熟度分析都显示了焉耆盆地在侏罗纪中晚期的2次成藏作用，即晚侏罗世以八道湾组低成熟油气的生成、运移和聚集为主的第1期成藏事件和侏罗纪末期以成熟油气的生成、运移和聚集为主的第2期成藏事件，受储层流体包裹体和自生伊利石形成机理的控制，第三纪晚期生烃、成藏事件在流体裹体和储层自生伊利石同位素年代学上均没有记录。侏罗纪末期是主要成藏期，第三纪晚期是调整成藏和定型期。     

森林火险气象指数的应用研究

利用全国575个国家级基本气象站1971年1月1日至2005年5月31日的气象观测资料, 选用了5种已得到国际普遍认可或我国国家级预警业务中使用的森林火险气象指数计算方法, 计算了我国长序列的历史逐日森林火险气象指数, 并对这些指数在我国的实际使用效果进行对比分析和应用研究。结果表明: I_FFD, I_NMC, I_N, I_MN指数可在我国大范围推广使用 (除长江中下游及附近地区), 其中以I_FFD指数总体应用效果最好, I_MN指数次之。     

气候变化背景下水资源脆弱性研究与展望

论述了气候变化背景下水资源脆弱性概念、内涵及其与适应性管理的联系;综述了水资源脆弱性定量评估方法,包括指标权重法、函数及综合指标法等;介绍了减少水资源脆弱性的适应对策研究。分析表明,联系水资源供需矛盾的水资源脆弱性既有自然变化脆弱性的一面,又有气候变化影响导致水资源供需关系发生变化以及旱涝灾害影响加剧水资源脆弱性的问题。关键是要识别影响水资源脆弱性变化的主要调控变量,通过应对气候变化的适应性对策研究,最大限度地减少水资源脆弱性。未来气候变化背景下水资源脆弱性研究,将在进一步发展脆弱性影响与评估基础上,逐步转到适应性水资源管理与对策的研究。     

ASOM系统实际应用存在的问题与处理

通过分析ASOM系统在实际应用中发现的问题,分析系统功能存在的欠缺或漏洞,并提出解决方法:做好自动站本身的监控软件和业务软件的监控,应用人工或其它业务软件快速审核地温,业务转型中新业务软件的监控要点。在仪器故障时按照ASOM业务流程做好仪器故障处理及上报工作。     

基于空间数据挖掘的遥感图像处理

数据与数据库的爆炸式增长导致了一个十分突出的问题,即如何高效、智能地从巨量的、有噪音的、随机的数据中提取有效的、潜在有用的信息和知识.近几年来,空间数据挖掘技术的广泛研究正是基于此目的.本文初步探讨了空间数据挖掘技术在遥感图像处理中的应用,其重点阐述了关联规则,以及数据挖掘技术在遥感图像数据处理中的基本方法以及如何对遥感图像数据进行离散化处理.文章最后简要介绍了遥感图像处理的决策树和人工神经网络数据挖掘技术方法.