Phase velocity of semi-diurnal internal waves at Ocean Weather Station T

Phase velocity of semi-diurnal internal waves is determined from differences between phases at three stations which were situated to form a triangle in the vicinity of sta. T (29N, 135E). The wave phases are estimated from temporal variations in depths of isotherms obtained from serial measurements of vertical temperature profiles at these stations. The measurements were carried out in cooperative operation of two vessels, the R. V.Tansei-maru and theNojima, during the period from 30 July to 1 August 1965. Wave propagation with the speed of about 2 m/s in the direction from east to west is obtained as an average over several isotherms of temperature from 19C to 23C. The area of measurement is to the west of Izu-Mariana ridge and the distance from the ridge to the station is about 500 km, which would be about 5 times as large as the wave length of the internal waves under consideration, and so it is possible to suppose that the internal waves observed generated at the ridge and propagated to the area without being subjected to serious refraction, scattering, reflection and decay.     

台风登陆广东沿海前后亮温相对功率谱的变化特征分析

在2008—2017年间登陆广东沿海的台风多达25个, 但台风登陆区域周边出现的热辐射异常现象并未引起太多关注。本文利用中国静止气象卫星FY-2C/2E红外遥感亮温资料, 对台风登陆引起的热辐射异常进行分析, 并使用亮温相对功率谱对台风登陆前后热辐射时空分布进行量化。研究发现: 伴随台风的登陆, 大于5倍以上背景值的亮温相对功率谱经历了产生—增加—极大值—减弱—消亡的过程, 其持续时间长于台风过程; 亮温相对功率谱增强的区域与台风登陆路径有一定的相关性, 受限于陆地条件和海洋热量供给; 通过分析台风登陆路径和台风登陆过程中亮温相对功率谱变化趋势可知, 台风登陆前后热辐射持续10~20d, 期间的热异常都与台风过程相关。台风登陆导致热辐射的机制可能与海洋表面降温、水汽聚集等因素有关, 即台风吸收的海洋热量随环流上升过程被海—气相互作用所调制, 导致不同频段和区域出现热辐射差异。     

台风Wayne过后南海北部陆架海域的近惯性振荡

1986年8月18日8616号台风维纳(Wayne)在南海中部生成,其后在南海北部迂回盘旋,前后3次穿越巴士海峡,9月4日在海南岛登陆。布放在海南岛东部陆架上的锚系浮标记录了台风中心过境前后风和近表层的海流响应。分析结果表明,台风中心过境造成海水强烈的近惯性运动,其影响大约持续了6—8d,近惯性振荡的频率为0.029 2周.h-1(周期约34.2h),高出当地的惯性振荡频率(0.028cph)4.3%。带通滤波所提取的惯性运动特征显示,台风过境后惯性振荡逐渐衰减,惯性圆逐渐向西南方向偏移。根据这一个例,探讨了台风条件下近表层流速与风速的关系以及台风尾迹中近惯性流流速衰减过程的经验描述,可为近海海洋工程设计提供参考。     

Response of a two-layer ocean to typhoon passage in the western boundary region

Effect of the typhoon passage on the western boundary region of a two-layer ocean with bottom topography is studied. The ocean is initially at rest and is set in motion by a typhoon passing parallel to the west coast. Equations that represent barotropic and baroclinic modes of motions are solved numerically by means of the method of finite differences. Motions of the barotropic mode are assumed to be horizontally non-divergent. In this mode, an elongated vortex is produced by the typhoon and propagates toward the south after passage of the typhoon. Behavior of the vortex may be interpreted as continental shelf waves. It is found that the formation and propagation of continental shelf waves are hardly affected by the density stratification. As for the baroclinic response, the typhoon causes considerable interface displacements along its track. The interface displacements are associated with geostrophic motions and remain for long time, though they are formed on the continental slope. Besides the large scale baroclinic response, internal Kelvin waves are induced along the artificial east wall.     

Bottom water temperature measurements in the South China Sea,eastern Indian Ocean and western Pacific Ocean

文章报道了一批新的海底底水温度(BWT)数据,其中南海(SCS)158个站位、东印度洋(EIO)30个站位及西太平洋(WPO)37个站位。基于这批新的BWT数据,获得南海和西太平洋海域底水温度与水深经验关系,可为地球物理和物理海洋提供准确、可靠的海底温度边界。这将有助于海底油气资源调查与评估。同时,这批实测数据表明:1)水深超过3500m的海域,其底水温度在南海约为2.47℃,比东印度洋(～1.34℃)和西太平洋(～1.60℃)稍微偏高。这与大洋传送带模式所预测的情况比较吻合。该模式认为:低温高盐的海水,从北大西洋格陵兰岛和冰岛附近海域下沉到深层,然后向南流动,再与南极洲周围海域的低温高盐海水一同向北进入印度洋和太平洋。而南海是一个相对比较封闭的热带边缘海,其内部海水与印度洋和菲律宾海交换有限,导致海水温度整体高于印度洋和太平洋。2)台西南盆地水深在2700～3000m的部分站位,其底水温高达约3.00℃,明显高于其周边同水深海域底水温度(平均值约为2.33℃)。这可能是台西南盆地海底水热活动导致的结果。3)在东印度洋和西太平洋水深超过4800m海域,底水温度随着水压增大稍有升高,其升高率分别为10.6mK·MPa~(-1)和12.0mK·MPa~(-1)。这与理论估算的深层底水绝热压力温度梯度范围较为吻合。这也意味着东印度洋和西太平洋深层底水,主要由绝热自压作用导致其温度随着深度的增大而升高。     

Structure and variability of current and water temperature fields near the Mascarene Ridge

An anticyclonic mesoscale eddy is found using the current and temperature data obtained at six moorings near the eastern foot of the Mascarene Ridge (Southern Hemisphere). Its spatial parameters radius, depth of penetration, and direction of the vertical axis tilt are given. The volume of water transported by the eddy across its radial section is calculated. Numerical characteristics of the spatial-temporal variability of the current and temperature field in the eddy are obtained. The relative contributions of the variability of mesoscale, tidal and inertial, and high-frequency oscillations are estimated.Translated by Mikhail M. Trufanov.     

秦山核电站邻近水域浮游植物的生态研究

本文分析了秦山核电站邻近水域生态零点调查四个航次的浮游植物样品,结果表明:调查区浮游植物的种数和细胞密度在时间尺度上均存在明显的季节变化趋势:夏大于秋大于春大于冬,并且与环境因子的变化密切相关,其中最主要的影响因子是温度、盐度和径流,而影响日变化的环境因子主要是潮汐。     

环境温度场的异常变化与台风的趋暖运动

根据美国国家环境预测中心(NCEP)的温度资料,以近年来在我国华东登陆或近海转向的台风为例,对台风中心附近的异常增温与未来移动方向进行诊断分析。结果发现:中、高层台风中心附近的异常增温对台风未来的移动趋势有着很好的指示作用,尤其是对台风的移动方向突然改变具有预报意义,强增温区及脊(轴)线方向预示着台风未来的移动方向。由此得出了一条台风路径预报的新途径。     

印度洋海温异常对西北太平洋台风的影响及机制研究

基于近40 a NCEP/NCAR再分析月平均高度场、风场、涡度场、垂直速度场以及NOAA重构的海面温度(sea surface temperature,SST)资料和美国联合台风预警中心(Joint Typhoon Warning Center,JTWC)热带气旋最佳路径资料,利用合成分析方法,研究了前期春季及同期夏季印度洋海面温度同夏季西北太平洋台风活动的关系。结果表明:1)前期春季印度洋海温异常(sea surface temperature anomaly,SSTA)尤其是关键区位于赤道偏北印度洋和西南印度洋地区对西北太平洋台风活动具有显著的影响,春季印度洋海温异常偏暖年,后期夏季,110°～180°E的经向垂直环流表现为异常下沉气流,对应风场的低层低频风辐散、高层辐合的形势,这种环流形势使得低层水汽无法向上输送,对流层中层水汽异常偏少,纬向风垂直切变偏大,从而夏季西北太平洋台风频数偏少、强度偏弱,而异常偏冷年份则正好相反。2)春季印度洋异常暖年,西北太平洋副热带高压加强、西伸;而春季印度洋异常冷年,后期夏季西北太平洋副热带高压减弱、东退,这可能是引起夏季西北太平洋台风变化的另一原因。     

红鳍东方鲀精子超低温保存前后的超微结构观察

应用透射电镜技术,研究超低温保存前后红鳍东方鲀(Takifugu rubripes)精子的超微结构。观察发现,受冷冻损伤精子的被膜膨胀、破裂、脱落;线粒体内嵴变形,结构模糊,甚至消失;鞭毛在基部或主段、末段断裂,或被膜膨胀脱落。结果表明,经超低温保存后,部分红鳍东方鲀精子由于膜结构及鞭毛轴丝损伤导致精子活力下降。     

西太平洋赤道附近海温与中国东南沿海台风关系的初步分析

本文对１９６０－１９９６年北太平洋月平均海表温度和中国东南沿海年台风资料的分析素材,初步揭示了两者之间联系。结果表明,西太平洋赤道附近海流区的海表温度不仅在同期具有高与台风多呈正相关关系。而且在前期存在关预测的先兆,特别是秋冬两季更加明显,具有较好的隔季相关关系。经建立预报方程,其趋势拟合率达８１．８％,试报３ａ,并准确率为６６．７％。     

A short history of Ocean Station Papa and Line P

This short article summarises the origins of observations at Ocean Station Papa, the evolution into Line P and the subsequent history of observations along that line.     

0519号台风"龙王"登陆福建沿海前后结构特征分析

通过利用双向嵌套中尺度非静力数值预报模式MM5V3对0519号台风"龙王"登陆福建前后过程(2005年10月2日08:00-3日08:00)进行了数值模拟,在模拟效果较理想的基础上利用其输出的高时空分辨率资料对"龙王"台风登陆福建沿海前后结构特征进行分析.结果表明:(1)登陆前后除暖中心在台风中心最强外,其它物理量的极值一般都出现在离台风中心100～200km区域;(2)台风登陆福建沿海后虽然在热力、动力和环流上还保留有热带气旋的一些分布特征,但在强度和空间分布上已经发生了明显的变化.     

Changes in topography and vegetation near gaps in a protective foredune

Data gathered on a foredune on a nourished beach reveal the relationships between topography and plant communities at gaps in the dune crest. Sand inundation at gaps allows plants in some portions of the dune to rejuvenate to earlier successional stages, while an increase in richness occurs in other portions. Ammophila breviligulata can create an initial dune ridge, colonize new areas of bare sand within the dune field, facilitate growth of other species, and provide a natural alternative to fencing in managing gaps. Foredune mobility can be considered a positive factor if beach width and dune volume provide adequate protection.     

铁山湾建港前后水体交换能力的数值模拟

铁山湾是北部湾东北部较大的海湾,水深条件好,可用岸线长。为研究铁山湾建港工程前后湾内的水体交换能力,文章建立了平面二维的水动力模型以及平面二维对流—扩散模型,率定后水动力学模型模拟结果与实测结果吻合良好。运用二维对流—扩散模型计算了湾内不同区域的水体半交换时间,模拟结果表明：铁山湾的水体交换能力较强,工程前水体半交换时间为129天,海域的水体交换能力主要受铁山湾潮汐作用的影响。铁山湾潮汐作用较强,潮差较大,且铁山湾口门开阔,这都为铁山湾的水体交换提供了良好的条件。工程后铁山湾水体半交换时间为142天,工程前后铁山湾水体半交换时间仅相差13天,说明工程方案对铁山湾水体交换能力无重大影响。     

海洋站自动观测设备智能监控报警系统设计

海洋环境观测数据是加强海洋行政管理、海洋环境保护和海洋防灾减灾能力建设的基础和重要技术保证,海洋环境观测数据的质量和时效在海洋灾害预警、防灾减灾中有着举足轻重的作用。保证观测数据的连续准确,不仅需要观测人员高度负责,而且还应配备稳定可靠、质量可行的观测设备和传送畅通的通信线路。随着海洋环境观测任务的增加和海洋观测自动化水平的提高,在观测设备运行中及时、准确地发现故障和查找问题亟须建立一套质量可靠、实时报警的监控系统。文章结合多年海洋站工作经验以及小麦岛海洋环境监测站实际情况,基于构建故障报警和监控系统在海洋站自动化观测系统中的作用,提出海洋站观测设备智能监控报警系统的设计构想,并对系统组成和系统应具备的功能进行论述。     

南极长城站大风天气分析和预报

本文使用常规气象观测资料及澳大利亚国家气象局发布的南太平洋天气实况分析图,分析了长城站2005年12月～2006年11月的大风天气。分析认为：长城站的大风天气主要出现在4～10月;气旋是造成长城站大风天气的主要天气系统;存在“单一气旋型”、“北高南低型”、“南高北低型”、“东高西低型”和“西高东南低型”五种大风类型,其主要风向分别是NW／SE,WSW-WNW,ENE-SE,NW-N和SW-WSW,最后给出了长城站冬、夏季节大风天气的预报思路。     

Formation and transport of intermediate water masses in a model of the Pacific Ocean

A basin-wide ocean general circulation model of the Pacific Ocean was used to investigate how the interior restoration in the Okhotsk Sea and the isopycnal diffusion affect the circulation and intermediate water masses. Four numerical experiments were conducted, including a run with the same isopycnal and thickness diffusivity of 1.0×103 m2/s, a run employing the interior restoration of temperature and salinity in the Okhotsk Sea with a time scale of 3 months, a run that is the same as the first run except for the enhanced isopycnal mixing, and a final run with the combination of the restoration in the Okhotsk Sea and large isopycnal diffusivity. Simulated results show that the intermediate water masses reproduced in the first run are relatively weak. An increase in isopycnal diffusivity can improve the simulation of both Antarctic and North Pacific intermediate waters, mainly increasing the transport in the interior ocean, but inhibiting the outflow from the Okhotsk Sea. The interior restoration generates the reverse current from the observation in the Okhotsk Sea, whereas the simulation of the temperature and salinity is improved in the high latitude region of the Northern Hemisphere because of the reasonable source of the North Pacific Intermediate Water. A comparison of vertical profiles of temperature and salinity along 50°N between the simulation and observations demonstrates that the vertical mixing in the source region of intermediate water masses is very important.     

Changes in the trophic structure of the southern Benguela before and after the onset of industrial fishing

Despite a human presence in the Benguela region for at least one million years, exploitation of marine resources by European seafarers only began in earnest in the 1400s. Ecopath with Ecosim was used to construct and compare mass-balanced foodweb models of the southern Benguela ecosystem, representing the following eras of human influence: aboriginal (10 000 BP–1651), pre-industrial (1652–1909), industrial (1910–1974) and post-industrial (1975–present). Biomass at higher trophic levels (TLs) decreased over the periods examined, whereas that of sardine and anchovy increased in the early 2000s, reflected by the decline in weighted TL of the community (excluding plankton). Fishing became an important predatory impact, taking over consumption of small pelagics and horse mackerel from declined natural predators such as hake. Harvesting of apex predators such as seals and seabirds during the pre-industrial era meant that the mean TL of the catch declined markedly between the pre-industrial (1900) and industrial (1960) models. Biomass removals by fishing have increased substantially over time. Total biomass, consumption, respiration, production and throughput decreased from the pristine model to 1960 and then increased again in the 2000s, probably influenced by the abnormally high small pelagic biomass in the early 2000s. Three additional alternate scenarios were examined for each of the retrospective models, in particular to explore the effects of removing large fish and forage fish from the system. Although biomasses and consumption of various groups in these scenarios differed from base models, indicators such as TL of the community and piscivore groups, and the diversity indices, were not altered much, suggesting that outputs from such retrospective models in the form of derived, relative indicators, may be more robust than comparisons of absolute flows, although the latter provide supplementary inferences. Although South African fisheries have certainly impacted ecosystem structure since their commencement, these effects are in addition to natural (specifically environmental) forcing that has always been influencing the system. Fishing stress at the ecosystem level and the collapse of small pelagic stocks may lead to a shift toward a bottom-up trophic control mechanism becoming the dominant driver of ecosystem dynamics, increasing the impact of environmental events including climate change. It is thus possible that pristine systems were not as severely affected by environmental anomalies as are modern systems.