南印度洋海区大风天气气旋概念模型研究

本文根据多年的天气图、卫星云图以及1980～1990年的NCEP再分析资料,通过统计分析和合成分析等方法建立了能够在南印度洋特定海区引起12m/s以上大风天气的中高纬气旋型天气概念模型,井对该天气概念模型作了详细的阐述.该天气概念模型主要发生在南半球的冬季和初春,在该模型中,气旋从高纬低压中分裂出来,快速东移赶上位于其东部的高位低压并发展至其北部.气旋冷锋最终在南印度洋东部引起大风.该天气概念模型的建立对南印度洋海区大风的预报可起到一定指导作用.     

渤海中西部近海与沿岸海雾的特征分析

利用2004—2012年渤海湾埕北油田A平台的气象水文观测资料以及塘沽、秦皇岛、兴城和龙口4个环渤海沿岸观测站的常规观测资料进行统计分析,得出渤海中西部海雾的气候特征及影响因子,归纳了天气系统模型,并给出了相关气象要素的定量化指标。结果表明:渤海海雾年际变化明显,其中2005年出现频次最少,2007年最多,不同海区海雾月际变化特征有所差异,但都存在冬季高发期,且海雾高发期受到温度空间分布的影响,08时海雾出现频次最多,其日变化特征受太阳辐射和海陆差异影响;依据高低空环流形势和地面主要影响系统,将渤海海雾发生时的天气形势分为均压场型,倒槽冷锋型,低压场型和高压场型4种并分别给出概念模型,各海区均压场型出现概率最高,渤海湾和莱州湾海区倒槽冷锋型次之,辽东湾海区低压场型占比第二;渤海海雾在海气温差正负时皆可出现且差值多在2℃以内,总体盛行风向特征不显著,这些特征与黄海海雾预报差异较大;此外,沿岸相对湿度达到90%以上,近海相对湿度达到80%以上,风速在0—3级之间,低层大气存在逆温层时,有利于渤海海雾的生成和发展。     

舟山市一次冬季暴雨、大风天气过程分析

应用卫星云图、常规观测资料及T213数值分析产品,分析了2004年12月3~5日发生在浙江东部地区的暴雨和舟山市沿海的大风过程。分析结果表明:这次天气过程是由台风倒槽和冷空气及深厚的高空槽共同作用引起的;台风环流引起的东南低空急流为暴雨区输送了大量的水汽和不稳定能量;冷空气的侵入加上深厚的高空槽引起的低空辐合、中高层辐散,促使了东海低压的剧烈发展,产生了猛烈的大风。     

浙江沿海大风的天气气候概况

用嵊泗站和大陈站资料对浙江省沿海大风的天气气候概况进行分析,结果表明浙北沿海平均每3d有1d出现大风,多于浙中南沿海(平均每7d有2d出现大风).浙北沿海以SSW大风最多,N大风次之;其中NNW—NE大风占46%,SSE—SW大风占43%;浙中南沿海以NNE大风最多,NE大风次之;其中N—ENE大风占77%,S—WSW占18%.浙北沿海大风以4月份最多,9月份最少;浙中南沿海大风以1月份最多,5月份最少;浙北沿海大风日数的月变化比浙中南小.浙江沿海大风的季风特征明显.浙江沿海冬半年大风多为冷空气大风,春季及初夏大风多为低压、倒槽引起,夏季大风主要是受热带气旋影响产生.     

EL NINO事件与东亚大气环流异常,振荡及与黑龙江省天气的关系

Ｅｌ ＮＩｎｏ事件发生前，春季阿留申低压异常发展，并有大量的动能由高纬向低纬输送，在Ｅｌ Ｎｉｎｏ发展时期，西太平洋副热带高压增强，东亚区５００ｈＰａ高度场呈现北负南正遥相关形势，我省易发生低温，Ｅｌ Ｎｉｎｏ现象减弱转为反Ｅｌ Ｎｉｎｏ时鄂霍次克海高压发展可以引起较大降水。Ｅｌ Ｎｉｎｏ指数与阿留申低压，东亚槽指数，副高面积指数同具有３．７５￣５年周期振荡，而且在３．７５年凝聚值最大，Ｅｌ Ｎｉ     

冀东油田作业海区大风特征分析及气象信息应用研究

利用冀东油田作业海区2013年12月—2014年11月的观测数据,分析了东、西、南部海区的大风特征,对产生大风的天气形势作了分型,并针对风、浪的专业站点观测值和现场人工经验观测值之间的差异作了对比分析,提出了释用方法。结果表明:(1)南部海区年大风日数最多,约为150 d,西部海区最少,约为100 d;(2)大风的季节性分布整体呈两峰两谷的趋势,5、11月是大风日数最多的月份;(3)各海区大风风向均以NW、WNW和ENE、E为主导风向,呈现出非常明显的"极端化"分布;(4)低槽冷锋是产生大风日数最多的天气系统,约占所有个例的一半;(5)专业自动站观测的风力均比现场人工经验观测的风力小,可提高1～3个等级后用于实际作业,自动观测的浪高普遍比人工观测的浪高小,可通过增加修正值或使用线性关系式予以运用。     

好望角航道的气候背景和灾害性天气系统

本文分析了好望角航道区的气候背景和灾害性天气系统，指出好望角航区的主要灾害性天气是大风，造成大风的主要原因是由南大洋的西风带以及大西洋的副高、印度洋副高和非洲大陆上的天气系统共同影响造成的。冬季西风带位置偏北，可达３０°Ｓ附近，西风带控制的范围也包括了非洲的南端大陆，以强西风为主，夏季西风带位置南移，影响航道区的系统有副高和西风带上绕极气旋的交替影响，除西向大风外，也常常会出现偏东和偏南大风。该区的海雾不多，以晴朗天气为主。受海洋性气候影响，气温的季节变化不大，冬季７～８月平均气温１４～１５℃，夏季１～２月平均气温２０℃左右。     

不同类型厄尔尼诺事件对印度洋秋季Wyrtki急流的影响

厄尔尼诺事件是发生在赤道太平洋地区的海气相互作用现象,根据海表温度时空演化特征可以划分为不同类型,即东部型、中部型。通过对再分析资料进行分析,指出不同类型厄尔尼诺事件发生时期,印度洋秋季Wyrtki急流(Wyrtki Jet,WJ)具有显著不同的变化特征,主要表现为:厄尔尼诺东部型事件发生期间,印度洋秋季WJ显著减弱,赤道印度洋表层海流表现为弱西向流;厄尔尼诺中部型事件发生期间,印度洋秋季WJ较历史同期水平增强。进一步分析表明,不同类型厄尔尼诺事件通过影响印-太海区大气沃克环流系统,调制了秋季赤道印度洋海表风场,进而调制了印度洋秋季WJ发生和发展。     

青岛沿海主要灾害性天气分析

本文论述了青岛沿海主要灾害性天气暴雨、大风和形成暴雨、大风的各种天气系统。青岛沿海暴雨强度的分布由南向北递减,该区暴雨多起于7月上旬止于8月下旬。暴雨中心在青岛以南,其特点是:暴雨开始早、结束晚、暴雨次数多,强度也大。影响本区暴雨的主要天气系统有:气旋、冷锋、台风、高压后部、静止锋和暖切变。大风是该区最常见的一种重要的灾害性天气,它对渔业、养殖、港工建筑及海上交通运输影响很大。本区大风的分布特点是:由海岛向陆地风力逐渐减小。全年以北向大风日数为多,尤以冬季最盛,南向大风主要出现在春季.引起本区域大风的天气系统主要有寒潮(冷锋)、蒙古(东北)低压、气旋、台风及雷雨。     

莱州湾海区与内陆大风对比分析

为了掌握莱州湾海区的大风规律,更好地为建设海上潍坊服务,本文利用自动气象站观测资料,对位于莱州湾南岸的羊口港、潍坊港、下营港梯度风塔3个港口和内陆的潍坊市城区寒亭国家气象观测一级站4个地方的大风进行了对比分析,并结合常规天气资料,分析了大风的季节变化特点以及与天气形势的关系。分析发现莱州湾海区平均风速是内陆的1.9倍,莱州湾风速东岸略大于西岸。南(东)高北(西)低是偏南大风出现时最常见的天气形势,冷锋后部的偏北大风是造成北部海区偏北大风最主要的形势。     

Assessing the Validity of Seismo-Acoustic Predictor Equations for Obtaining Seabed and Sub-Surface Sediment Physical Properties

The interdependence between the seismo-acoustic properties of a marine sediment and its geotechnical/physical parameters has been known for many years, and it has been postulated that this should allow the extraction of geotechnical information from seismic data. Though in the literature many correlations have been published for the surficial layer, there is a lack of information for greater sediment depths. In this article, a desktop study on a synthetic seafloor model illustrates how the application of published near-surface prediction equations to subsurface sediments (up to several tens of meters burial depth) can lead to spurious predictions. To test this further, acoustic and geotechnical properties were measured on a number of sediment core samples, some of which were subjected to loading in acoustically-equipped consolidation cells (oedometers) to simulate greater burial depth conditions. For low effective pressures (representing small burial depths extending to around 10 meters subsurface), the general applicability of established relationships was confirmed: the prediction of porosity, bulk density, and mean grain size from acoustic velocity and impedance appears generally possible for the investigated sedimentary environments. As effective pressure increases through, the observed relationships deviate more and more from the established ones for the near-surface area. For the samples tested in this study, in some instances increasing pressure even resulted in decreasing velocities. There are several possible explanations for this abnormal behavior, including the presence of gas, overconsolidation, or bimodal grain size distribution. The results indicate that an appropriate depth correction must be introduced into the published prediction equations in order to obtain reliable estimates of physical sediment properties for greater subsurface depths.     

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。     

Interannual Sea Level Variations and Annual Tides in the Northwestern Pacific

Specific properties of the interannual sea level variations and annual tides in the Northwestern Pacific were studied. Several tide stations were monitored. The monthly mean sea level for the year of 1995 was analyzed at each tide station. A seismic event in 1995, some tectonic activity around the subject area, and the Kuroshio (the oceanic western boundary current) may possibly contaminate results which would have occurred from the astronomical annual tide alone.     

Flow Cytometric Analysis of Coastal Lagoon Bacterioplankton and Picophytoplankton: Fixation and Storage Effects

The effect of different fixation and storage protocols on the flow cytometric (FCM) simultaneous analysis of bacterioplankton and phytoplankton in coastal seawater samples (Mediterranean coastal lagoons) was investigated. FCM measurements (cell number, fluorescence and scatter characteristics) were obtained through DAPI staining. Three fixatives [glutaraldehyde (GA), formaldehyde (FA) and paraformaldehyde (PFA)] and two storage (3 months duration) methods (5 °C and −196 °C) were tested. Two dominant populations were detected in studied samples: bacteria and eukaryotic picophytoplankton. Adding fixatives (2% final concentration) appears necessary to obtain FCM exhaustive counts of all the bacteria and phytoplanktonic cells. This was related to the permeation effect of fixatives which allowed a better DAPI staining of the cells. Maximum fluorescence, i.e. optimal staining of the cells was obtained with FA or PFA, and significant lower fluorescences with GA. Fixed samples stored at 5 °C induced rapid cell loss. Only storage in liquid nitrogen of samples fixed with FA or PFA, allows mid-term (≥4 months) preservation of bacteria or picophytoplankton cell numbers, and limited evolution of DAPI-induced fluorescence and scatter characteristics.     

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.     

INFORMATION FOR AUTHORS

<正>Acta Oceanologica Sinica(AOS)is a comprehensive academic journal edited by the Editorial Committee of Acta Oceanologica Sinica and is designed to provide a forum for important research papers of the marine scientific community which reflect the information on a worldwide basis.The journal publishes scholarly papers on marine science and technology,including physics,chemistry,biology,     

Estimation of Sediment Properties during Benthic Impact Experiments

Sediment properties, such as water content and density, have been used to estimate the dry and wet weights, as well as the volume of sediment recovered and discharged, during benthic impact experiments conducted in the Pacific and Indian Oceans. The estimates show that the weights of dry (355-1332 t) and wet sediment (1651-4888 t) recovered during the experiments, are not only a function of the total duration and distance covered during the experiment, but also depend on water content and density of the sediment. Estimation of dry sediment and its volumetric ratio in the discharge, are key parameters for calculating the discharged volume. The estimated volume of wet sediment recovered (1427-4049 m 3 ) as well as discharged (2693-6951 m 3 ) during the experiments, provide important inputs to evaluate the sediment resettlement and migration. Using these estimates, the average depth of excavation on the seafloor, can also been calculated. However, the stages of sediment recovery and discharge are expressed differently in some of the experiments. In order to standardize these, different stages have been identified, and definitions of certain terms have been suggested, for use in the future. The methods of calculating different properties, as well as weight and volume of discharged sediment are described in the paper for use in other applications concerning deep-sea discharges.