大西洋浪蛤(Spisulasolidissima)人工繁殖 初步试验

1999年5～6月对大西洋浪蛤进行人工繁殖试 验。结果表明,大西洋浪蛤一年能达到性成熟,一个繁殖季节产卵一次,卵为球形,卵径为 50～60μm;在23℃左右水温下,受精卵经16～20h发育成D形幼虫,幼虫浮游期为16～20d; 壳长260～290μm时为附着变态阶段。幼虫培育盐度要求在16以上。     

圆阵低频超增益波束形成用于水下目标探测研究

针对小尺度基阵难以取得低频空间增益的问题,研究了圆阵超增益波束形成技术检测低频目标的方法。利用小尺度基阵低频噪声的空间相关性,求出基阵的相关系数矩阵,该矩阵对常规波束形成的权系数进行加权,产生超增益波束形成器的最优加权向量。计算机仿真与实测数据处表明：超增益波束形成技术能够在较低的工作频率上形成波束,获得更好的探测定位性能,有良好的应用前景。     

北极高密集度冰区海冰的多时间尺度变化特征及其极端低值事件分析

利用美国冰雪中心(NSIDC)高分辨率海冰密集度等多种数据,定义了北极高密集度冰区(High concentration ice region:HCIR)海冰变化指数,在此基础上研究了1989—2017年HCIR海冰多尺度变化特征及其极端低值事件的可能形成原因。结果表明:北极HCIR海冰密集度具有显著的单峰型季节变化特征,4月密集度最高,9月密集度最低,年较差达17.70%,兼有夏季融冰期短、冬季结冰期长且持续稳定的特点。HCIR海冰存在显著的年际年代际变化,在2007年发生了年代际转折以后,海冰变化指数的年际变化幅度和频次明显加强,且在2016、2012、2007、2011、2008和2010年依次出现海冰密集度极端降低事件;2016年9月初HCIR海冰密集度达到历史最低值,接近50%。对HCIR海冰密集度极端低值事件的统计研究表明,29年间共出现874天(次)极端低值事件,约占总频次的8%;空间上海冰密集度的降低主要出现在沿HCIR边界线一带,存在巴伦支海-喀拉海北缘的斯瓦尔巴群岛-北地群岛和东西伯利亚-波弗特海两个中心区域,该空间分布与气旋式大气环流引起的北冰洋Ekman漂流的辐散分布相一致。这表明HCIR海冰密集度的极端降低与极涡的动力作用有关,同时风场对海冰的动力辐散作用还会引起HCIR开阔水域的扩大,进一步加强海冰反照率的正反馈机制,使得热力和动力作用耦合起来共同影响HCIR海冰的加速融化。     

Effect of the Bottom Topography on Tsunami Propagation in the East （Japan） Sea

A study of tsunami events in the East （Japan） Sea using continuous Galerkin finite element model, aiming at reproducing tsunami waves generated by underwater earthquakes in 1983 and 1993 respectively has been performed focusing on the geographic extent of a topographic feature in the East （Japan） Sea. Numerical models can be the proper tools to study the combined effects of realistic topography. Subsequently, using the FEM based two-dimensional model we have simulated the smoothed and flattened topographic effects by removal of Yamato Rise and seamounts for the cases of tthe 1983 Central region earthquake tsunami and the 1993 southwestern Hokkaido earthquake tsunami. The results have shown that there will be higher tsunamis along the eastern coasts of Korea in general except some areas, like Sokcho with removal of topographic highs, thus providing complicated bottom topography of the East （Japan） Sea as effective tsunami energy scattering.     

Formulation, implementation and examination of vertical coordinate choices in the Global Navy Coastal Ocean Model (NCOM)

A 1/8° global version of the Navy Coastal Ocean Model (NCOM) is described with details of its formulation, implementation, and configuration of the vertical coordinate. NCOM is a baroclinic, hydrostatic, Boussinesq, free-surface ocean model that allows its vertical coordinate to consist of σ coordinates for the upper layers and z-levels below a user-specified depth. This flexibility allows implementation of a hybrid σ–z coordinate system that is expected to mitigate some of the weaknesses that can be associated with either pure coordinate option. For the global NCOM application, the σ–z coordinate is used to allow terrain-following σ coordinates in the upper ocean, providing better resolution and topographic fidelity in shelf regions where flow is most sensitive to its representation. Including z coordinates for deeper regions efficiently maintains high near-surface vertical resolution in the open ocean. Investigation into the impact of the selected coordinate system focuses on differences between atmospherically-forced free-running (no assimilation) global solutions using σ–z and pure z coordinates. Comparisons with independent temperature observations indicate that global NCOM using the σ–z coordinate has improved skill relative to its z coordinate implementation. Among other metrics, we show that in comparison with time series of surface temperature from National Oceanic Data Center (NODC) buoys, mostly located in coastal regions, root mean squared differences (RMSD) improved for 63% and correlation improved for 71% of the stations when σ–z coordinates were used instead of pure z. For the exclusively open-ocean Tropical Atmosphere-Ocean (TAO) buoys, differences between the simulations were small, with the σ–z showing smaller RMSD for 45% of the stations and higher correlation for 65% of the stations. Additional comparisons using temperature profile observations further confirm a tendency for improved performance using the hybrid σ–z coordinates.     

Numerical prediction experiment on Typhoon Maggie (9903)

I~IOXTyphoon is a severe and diSaStrous weather phenomenon that affeCts the southeaSt COaStsregion of China. It causes Serious lOSS for the social eCOnondc development as well as the life andproperties Of PeOPle. Therefore, the enhancement to study on the artifice of monitoring, Prediction and public services of typhoon is an i~nent requirement for gove~t and Public.The concern is also a taSk of great Urgency to advanCe meteorolQgical sciences.Starting from the 1980' s, as the deve…     

台风Maggie(9903)的数值预报试验

台风Maggie(9903)的移动路径属于历史上罕见的疑难路径之一,在1999年6月6日0时(UTC,下同),台风位于22.3°N,119.8°E附近,它向西北方向移动,于6月6日12时抵达广东汕尾附近海面,然后沿海岸线折向西南行,于6月7日下午到达阳江附近海面,经历一次360°的打转后再折向北行在阳江登陆,澳门地球物理暨气象局以MM5为基础的台风数值预报试验系统在6月6日0时相当准确地报出Maggie的未来48h移动路径和降水,敏感性试验说明,华南大陆的海岸线走向和地形对Maggie的移动路径无明显的影响,它之所以沿海岸线折向西南行应是其环境场改变的结果,把华南陆地变为海洋后,Maggie在向西南移动过程中继续发展,这说明,当台风接近陆地或登陆后,陆面摩擦和下垫面水气供应的减少是引起台风减弱的主要因子。     

简单热带海气耦合模式中的海洋低频扰动

讨论简单热带海气耦合模式中的低频海洋扰动。研究结果表明,挟卷对海洋Ｒｏｓｂｙ波的发展起抑制作用,而平流有利于海洋Ｒｏｓｓｂｙ波的发展;挟卷和平流都有利于与海温距平相对应的扰动Ｕ的发展     

Validation of interannual simulations from the 1/8° global Navy Coastal Ocean Model (NCOM)

A 1/8° global version of the Navy Coastal Ocean Model (NCOM) is used for simulation of upper-ocean quantities on interannual time scales. The model spans the global ocean from 80°S to a complete Arctic cap, and includes 19 terrain-following σ- and 21 fixed z-levels. The global NCOM assimilates three-dimensional (3D) temperature and salinity fields produced by the Modular Ocean Data Assimilation System (MODAS) which generates synthetic temperature and salinity profiles based on ocean surface observations. Model-data intercomparisons are performed to measure the effectiveness of NCOM in predicting upper-ocean quantities such as sea surface temperature (SST), sea surface salinity (SSS) and mixed layer depth (MLD). Subsurface temperature and salinity are evaluated as well. An extensive set of buoy observations is used for this validation. Where possible, the model validation is performed between year-long time series obtained from the model and time series from the buoys. The statistical analyses include the calculation of dimensionless skill scores (SS), which are positive if statistical skill is shown and equal to one for perfect SST simulations. Model SST comparisons with year-long SST time series from all 83 buoys give a median SS value of 0.82. Model subsurface temperature comparisons with the year-long subsurface temperature time series from 24 buoys showed that the model is able to predict temperatures down to 500 m reasonably well, with positive SS values ranging from 0.18 to 0.97. Intercomparisons of MLD reveal that the model MLD is usually shallower than the buoy MLD by an average of about 15 m. Annual mean SSS and subsurface salinity biases between the model and buoy values are small. A comparison of SST between NCOM and a satellite-based Pathfinder data set demonstrates that the model has a root-mean-square (RMS) SST difference of 0.61 °C over the global ocean. Spatial variations of kinetic energy fields from NCOM show agree with historical observations. Based on these results, it is concluded that the global NCOM presented in this paper is able to predict upper-ocean quantities with reasonable accuracy for both coastal and open ocean locations.     

Propagation and trapping of inertial gravity waves in shear flows (ray theory)

The process of propagation and trapping of inertial gravity wave (IGW) packets in oceanic shear flows is studied in the geometric-optics approximation (ray theory). It is shown that wave trapping in strong stable stratification occurs in the region of anticyclonic (horizontal) velocity shear in a narrow frequency range on the left side of the inertial frequency. Beyond this range, the packet (ray) is either reflected from a cyclonic shear layer or propagates freely through the shear layer. The basic equations of ray theory are analyzed qualitatively, and analytical expressions are derived for freely propagating and trapped rays. The influence that vertical shear exerts on the ray behavior is also investigated. It is shown that two-dimensional ray focusing occurs as the velocity profile decreases with depth, so that rays concentrate along a specific latitude.     

Cycling the Representer Method for 4D-variational data assimilation with the Navy Coastal Ocean Model

The Cycling Representer Method, which is a technique for solving 4D-variational data assimilation problems, has been demonstrated to improve the assimilation accuracy with simpler nonlinear models. In this paper, the Cycling Representer Method will be used to assimilate an array of ADCP velocity observations with the Navy Coastal Ocean Model (NCOM). Experiments are performed in a high-resolution Mississippi Bight domain for the entire month of June, 2004 and demonstrate the usefulness of this assimilation technique in a realistic application.The Representer Method is solved by minimizing a cost function containing the weighted squared errors of velocity measurements, initial conditions, boundary conditions, and model dynamics. NCOM, however, is a highly nonlinear model and in order to converge towards the global minimum of this cost function, NCOM is linearized about a background state using tangent linearization. The stability of this tangent linearized model (TLM) is a very sensitive function of the background state, the level of nonlinearity of the model, open boundary conditions, and the complexity of the bathymetry and flow field. For the Mississippi Bight domain, the TLM is stable for only about a day. Due to this short TLM stability time period, the Representer Method is cycled by splitting the time period of the assimilation problem into short intervals. The interval time period needs to be such that it is short enough for the TLM to be stable, but long enough to minimize the loss of information due to reducing the temporal correlation of the dynamics and data. For each new cycle, a background is created as a nonlinear forecast from the previous cycle’s assimilated solution. This background, along with the data that falls within this new cycle, is then used to calculate a new assimilated solution. The experiments presented in this paper demonstrate the improvement of the assimilated solution as the time window of the cycles is reduced to 1 day. The 1-day cycling, however, was only optimal for the first half of the experiment. This is because there was a strong wind event near the middle of June that significantly reduced the stability of the 1-day cycling and caused substantial errors in the assimilation. Therefore, the 12-h cycling worked best for the second half of the experiment. This paper also demonstrates that the forecast skill is improved as the assimilation system progresses through the cycles.     

Gram Stain Index (GSI) of Bacterial and Archaeal Cells in the Natural Microbial Communities of Slightly and Extremely Saline Environments

The use of GSI (Gram Stain Index) was studied for natural microbial cells in slightly and extremely saline environments. The GSI spectra of archaeal cells in an extremely saline environment showed unique profiles, different from those of Bacteria. These profiles can be applied for structural analysis of the microbial communities in aquatic environments.     

Propagation of Antarctic Bottom Water in the Discovery Gap (Northeast Atlantic) Based on Measurements from 2019

Oceanology - The results of the analysis of the thermohaline water parameters of the bottom layer in the Discovery Gap (Azores-Gibraltar Fracture Zone, Northeast Atlantic) are presented. The data...     

Downward particle fluxes within different productivity regimes off the Mauritanian upwelling zone (EUMELI program)

A 2-yr record of downward particle flux was obtained with moored sediment traps at several depths of the water column in two regions characterized by different primary production levels (mesotrophic and oligotrophic) of the eastern subtropical North Atlantic Ocean. Particle fluxes, of ∼71–78% biogenic origin (i.e. consisting of CaCO₃, organic matter and opal) on average, decrease about six-fold from the mesotrophic site (highest fluxes in the North Atlantic) nearer the Mauritanian margin (18°30′N, 21°00′W) to the remote, open-ocean, oligotrophic site (21°00′N, 31°00′W). This decrease largely reflects the difference in total primary production between the two sites, from ∼260 to ∼110 g organic C m⁻² yr⁻¹. At both sites, temporal variability of the downward particle flux seems to be linked to westward surface currents, which are likely to transport seaward biomass-rich water masses from regions nearer the coast. The influence of coastal upwelling is marked at the mesotrophic site. The large differences between the 1991 and 1992 records at that site, where carbon export is large, underscore the interest of long-term studies for export budget estimates. The different productivity regimes at the two sites seem to induce contrasting downward modes of transport of the particulate matter, as shown in particular by the faster settling rates and the higher E ratio (particulate organic carbon export versus total primary production) estimated at the mesotrophic site.     

Proposing a coordinated environmental effects monitoring (EEM) program structure for the offshore petroleum industry,Nova Scotia,Canada

Environmental effects monitoring (EEM) identifies, quantifies, and compares predicted environmental impacts of a proposed industrial project to those observed after the project has been developed. Several EEM program structures exist, while the structure used by Environment Canada to monitor impacts of the pulp and paper industry has proven to be effective. The aim of this study is to provoke discussion on the development of an effective and coordinated petroleum EEM program structure for the offshore of Nova Scotia, Canada. A structure that supports development of a national EEM program for the petroleum industry is then proposed. Advantages of a coordinated EEM program structure include: (1) reduced cost of the EEM; (2) fewer gaps and less overlapping of responsibilities; (3) fewer calculated risks to the marine environment; and (4) improved environmental safeguards.     

Frequency of tidal storm surge at New York harbor (New York) and Newark bay (New Jersey)

A joint probability analysis of storm tides is made for the Battery, New York (U.S.A.), and Newark Bay, New Jersey (U.S.A.). Storm tides are caused by either low-pressure coastal storms (northeasters) or hurricanes. The analysis uses existing gage data at the Battery to construct frequency/probability curves of peak surge elevations and tidal amplitudes. These are used in a computer program to combine standard storm surge stages and tidal stage curves to produce an artificial storm tide with given peak elevation and incremental frequency. These peak elevations and incremental frequencies are ranked to produce cumulative frequency curves for northeasters and hurricanes. A frequency curve is obtained for Newark Bay via correlation.     

Low frequency variability of the currents in Indonesian channels (Savu-Roti and Roti-Ashmore Reef)

Direct current measurements of one year duration were obtained in two Indonesian channels, between Savu and Roti and in the Timor Passage. Their analysis, together with data from Indonesian coastal tide gauges, supports the rather high value of transport deduced from geostrophic calculations across the hydrographic section made in August 1989. At that time, the Timor Passage may have fed more than half of the throughflow. A strong variability was observed in the form of sudden changes in the current regime with amplitude of the same order as the seasonal one. Observations indicate the importance of sea level measurements along the Indonesian coast, which show some correlation with the flow through the Timor Passage.     

低分子量肝素的制备及其结构与活性差异

低分子肝素作为一种抗血栓的多糖药物在临床中已应用了二十多年 ,目前已作为外科预防血栓形成药物 ,并在治疗急性静脉栓塞紊乱方面取代了未分级肝素。因肝素的来源和制备的方法不同使低分子肝素的精细结构不同 ,低分子肝素结构的复杂性 ,使得各产品的生物活性 ,例如抗蛋白酶活性不同 ,从而导致其临床使用的标准不同。该文将对低分子肝素的制备方法及其结构和抗蛋白酶活性的差异进行报导