热带气旋“麦莎”和“韦帕”在浙江产生大风对比分析

热带气旋“麦莎”登陆玉环,“韦帕”登陆苍南霞关,登陆点均在浙江南部,登陆点距离不超过150 km,登陆时强度相同,离境点的位置只相距50 km,但产生的大风和分布有很大的不同,“麦莎”在浙江境内产生的大风强度、范围、都比“韦帕”大得多,持续时间也要长很多.本文通过对两个热带气旋登陆前后的热带气旋自身的变化、移动的路径及速度和环境场等特征对比分析,发现登陆后减弱速度、路径与地形、副热带高压调整、气压梯度、热带气旋中心与测站的距离不同是两者产生大风不同的主要原因.     

多波束测深声呐成像仿真及作用距离分析

AUV 等无人装备研制过程中如何选择合适的多波束测深系统以满足特定作业场景需求是工程技术人员关心的问题之一。从多波束测深声呐系统与 AUV 等无人系统的匹配角度出发,采用混响背景下的主动声呐方程建立了不同工作频率多波束作用距离计算评估方法,对 100 kHz~500 kHz 的多波束测深声呐作用距离进行了计算对比。在此基础上,采用线性调频、FFT 波束形成、脉冲压缩、样条插值扩充目标角度、Rife 算法优化角度估计技术,建立了多波束测深声呐的成像仿真方法,并通过直线地形、台阶地形对多波束测深声呐的成像特点和测深分辨率进行了分析。主要结论：1）建立了一种多波束作用距离评估的方法,可用于指导无人装备用多波束测深声呐频率参数的选型;2）建立的多波束测深声呐仿真办法可以帮助工程技术人员更直观地理解多波束测深声呐的成像特点;3）通过仿真分析了 CW 信号与线性调频信号下的距离分辨率,可用于指导波束测深作业时的高度、信号参数设置。     

Occurrence of the toxic dinoflagellate Ostreopsis cf. ovata in relation with environmental factors in Monaco (NW Mediterranean)

To study environment characteristics favoring the toxic benthic dinoflagellate Ostreopsis cf. ovata, a survey was conducted in Monaco (NW Mediterranean Sea), in summers 2007 and 2008. Epiphytic and planktonic blooms occurred almost simultaneously and a high variation of abundances at low spatial scales was observed. An early and very marked bloom occurred in 2007, compared to a later and less abundant development in 2008. These distinct patterns in bloom timing corresponded with very different hydroclimatic scenarios in 2007 (hot spring and relatively cold summer) and 2008 (standard year compared to the median year profile estimated with data from 1995 to 2008). No clear impacts of summer seawater temperature, rainfall or nutrient concentrations were evident. Strong wind may favor the dispersal of benthic and planktonic cells. Our study suggests that further investigations are needed to examine the potential role of Ostreopsis nutritional mode (i.e. autotrophy vs. mixotrophy).     

早前寒武纪大陆地壳的性质与构造演化问题

世界大陆地壳主要由早前寒武纪英云闪长质花岗岩类组成,并于太古宙晚期普遍经历了克拉通化。迄今尚未证实世界是否保存有未经受早期强烈改造和重熔分异轮回的原属地球的初始基性岩壳。华北克拉通是世界典型太古宙克拉通陆块之一。这些古陆块的规模、刚性特征和地质构造等,都直接显示出与现今板块理论基本模式一致。大陆地壳经早期高增生率阶段,又经裂解和聚合演化而形成不同时代的地体拼贴而成的现今世界大陆。它们并非由陆核增生,而现代大陆演化则深受先存拼合地体的影响,在全球板块运动过程中大陆各地体块体因重力均衡及张剪、压剪的走滑发生调整。古陆块虽经长期剥蚀而至今仍为大陆,是因下地壳区的挤压环境促使发生近水平面状强烈韧性剪切、板底垫托和滑脱,导致岩片叠置使陆壳垂直增生,而获得浮力,并可因超负荷增大而形成下地壳高压麻粒岩相区。由反映强弱应变的变形分隔的深成构造作用机制所造成的地壳水平网络状结构,在地学大断面内是最主要的特征之一。     

The science and management of the North Sea and the Baltic Sea: natural history, present threats and future challenges

The review provides an overview of the features of the North Sea and the Baltic Sea in their European geographical and socio-political context. To reach sustainability in the wider sense the common society has to meet the 7 tenets - that management actions have to be environmentally sustainable, economically viable, technologically feasible, socially desirable (or at least tolerable), legally permissible, administratively achievable and politically expedient. Each of these are explained and discussed using examples from the two seas including pollution control, physical resource exploitation (such as aggregates, habitat loss, renewable energy and oil and gas), and biological resources exploitation (fisheries and aquaculture). This paper discusses the similarities between the areas in terms of their management regimes, population in the catchment, history of anthropogenic changes, derivation of objectives against a wealth of information and understanding, and the history of management and control. In contrast, the differences between the areas centre on their differing hydrographic regimes, including residence and flushing times, biological features, nature of the pollutants discharged, dominant types of fishing and type of control indicated by a predominant Eastern Bloc for the Baltic as opposed to European Union control in the North Sea. The review ends with an assessment of future challenges and examples of the way in which environmental problems have been addressed in the two areas. In particular, it sets the features against a background of management designed to achieve the Ecosystem Approach within the prevailing European marine management framework.     

Aliphatic and aromatic hydrocarbons in coastal Caspian Sea sediments

This investigation represents the first extensive study of the spatial distribution and sources of aliphatic (n-alkanes and unresolved complex mixture of fossil hydrocarbons) and polycyclic aromatic hydrocarbons (PAHs) in coastal sediments from the Caspian Sea. PAH concentrations, n-alkanes and biomarker profiles all suggested that there was limited petrogenic contamination in the shallow North Caspian Sea sediments, which are coarse with a low total organic carbon content. In contrast, moderate to high petrogenic contamination was found in the South Caspian Sea, in particular in the offshore oil fields near Baku, Azerbaijan. Contaminant patterns indicated that the PAHs were mainly from fossil sources, with higher contributions of pyrolytic only near industrialized and urban areas. A high contribution of perylene, a geochemically derived PAH, to the total PAHs was found in the west and south at sites influenced by the Kura, Safid Rud, Terek, Sulak and Samur Rivers.     

腾冲火山地区的地震活动特征

对腾冲火山地区的地震活动时空分布及震情参数的研究结果表明，与火山活动区有关的地震活动具有以下特征：周围构造地震活动频繁而火山群地区则处于地震活动相对平静的背景，震级较低（最高为５．０～６．０级）；地震活动以小的震群活动为主，微震主要发生在腾冲县城南部的热海热田地区。长期的地震频率ｂ值高，达１．２左右；震源深度在０～２０ｋｍ范围，受周围构造大地震的影响，导致火山区地壳内部岩浆活动引起的岩浆冲击型地震发生；火山体地下低速层的存在与地下热物质有关。从腾冲火山活动区地震的时空分布特征和震情参数特征表现出与世界上其它火山地震的相似关系，表明腾冲火山不是死火山，火山体地壳内部存在的岩浆囊或岩浆移动通道内岩浆仍在活动。