粘性-地形修正项对潮汐数值模拟影响的研究

目前近海海洋模型大多从近海地形变化剧烈和细化浅水分层两个方面综合考虑,垂向坐标通常采用σ坐标变换,并且一般情况下均忽略了在坐标转换过程中出现的粘性-地形项.以POM海洋数值模式(Princeton OceanModel)为基础,在对渤、黄、东海M2分潮潮波的模拟中,具体分析了εu,εT,εs粘性-地形修正项对东中国海M...     

Three Kings Ridge: a west-facing arc

The Three Kings Ridge has been described as a remnant arc or an east-facing arc on the western side of the South Fiji Basin under which symmetric South Fiji Basin magnetic anomaly lineations have been lost. We find evidence of neither arc-trench morphology on the eastern flank of the ridge nor collision tectonism within the adjacent South Fiji Basin that might have obliterated it. We believe there is room for the missing magnetic lineations within the South Fiji Basin and we recognize the distinctive island-arc morphology characteristic of a west-facing arc on the western flank of the Three Kings Ridge. Our interpretation requires that arc volcanism postdated formation of much of the South Fiji Basin and that oceanic lithosphere from the adjacent Norfolk Basin must have been subducted beneath the west-facing Three Kings Arc.     

A shipborne magnetic survey in Hudson Bay

A marine magnetic total-field survey of Hudson Bay was conducted from 1975 to 1978. Approximately 62 000 line-km of data, or 35 000 five-minute averages, were acquired. The data were corrected for secular variation by means of a polynomial in latitude, longitude, and time, first fitted to annual mean differences from nine observatories and then integrated over time. The data were corrected for diurnal and transient variations by means of a linear interpolation, over geomagnetic latitude, of running hourly mean values from two neighbouring magnetic stations (numbering seven in all). Crossover differences are analysed in terms of a mixture of normal distributions resulting from the intermittent transient variations, and indicate the effectiveness of the corrections. The variance of the data is reduced, as a result of the corrections, by 87% during quiet periods and by 53% during disturbed periods, the weighted variance being reduced by 66%. Navigational accuracy is estimated, from a novel method utilizing crossover differences and field gradients, to be approximately 300 m. Anomalies are presented in profile form, and discussed briefly.Contribution from the Earth Physics Branch No. 973.     

A low level supplementary heating system for free divers

A simple and effective method of heating divers in extreme cold water has been developed. The local heating concept utilizes a uniformly distributed granular mixture of magnesium and iron particles packed in small sachets. Upon activation by sea water, the two metal mixture behaves as a multitude of short-circuited electrolytic cells, producing thermal energy rather than electrical energy. The 45 mm-square sachets may be placed where heating is required on the diver's body, thus giving rise to the term “local heating”, obviously, the heating system requires no pumping device, or distribution network. Heating rate and duration of output of the sachets are controlled by particle size, and mixture ratio of the constituent Mg and Fe particles.This paper described the development, testing and performance of the heating sachets. Results of live tests in different dive situations are also presented and discussed.     

Investigation of internal waves generated by a diurnal barotropic tide in the vicinity of an oceanic ridge

Internal waves occurring near an oceanic ridge as a result of impingement of a barotropic tide are scrutinized in terms of the long theory for long waves. The ocean is assumed to be double-layered, the relief continuously changing, and the tidal wave on-running at an arbitrary angle. The dependences of the wave amplitudes and horizontal velocities on the ridge's latitude, the angle of tide running, and the depth of the density jump layer are obtained. Similar investigations for the model bottom relief have been conducted in refs 1 and 3.Translated by Vladimir A. Puchkin.     

Heated diver decompression shelter: The “womb concept”

A hybrid thermal protection method using waste heat from a surface-mounted outboard motor is shown to create a warm “micro-climate” environment for divers. The effects of surface heater capacities, water flow rates, shelter volume and shelter insulation on micro-climate temperatures are characterized. During long, cold-water decompression stops this method offers a reliable, low-cost alternative to surface-supplied hot water suits or diver-carried heating systems. An added bonus for divers using closed-circuit breathing apparatus is prolonged durations of their carbon dioxide scrubbers when surrounded by the warm water “micro-climate”. Closed-circuit and open-circuit options of this diver decompression shelter concept are evaluated.     

Shallow-Water Gasohydrothermal Vents of Ushishir Volcano and the Ecosystem of Kraternaya Bight (The Kurile Islands)

Abstract. A marine ecosystem in the crater of the Ushishir Volcano (Kraternaya Bight, Yankich Island, the Kuriles) showing gasothcrmal activity was studied for hydrographical, hydrochemical, and biological characteristics. Maximal changes in chemical and biological characteristics were observed in the surface water layer of 0–5 m. This layer had higher water temperature, was saturated with volcanogcnic carbon dioxide (up to 2000 10^-6 torr), ovcrsaturatcd with oxygen (up to 200 %), and contained high concentrations of chlorophyll a. Hydrogen sulfide was found in the surface water layer and at a depth of 15 m in the area of maximal effect of volcanic effluents.
The planktonic community is characterized by high rates of production and destruction of organic matter only in the 0–5 m layer. Daily vertical migrations of the ciliatc Mesodinium rubrum were observed, which caused "red tides".
Bacterial, algobacterial, and diatom mats developed on the bottom of the bight in the zone of gasohydrothermal vents and in areas of volcanic water seeping. The rate of organic matter production in algobacterial mats reached 33.4g C-rrr²-d^-l, chcmolithotrophy predominating. Bottom settlements had high population density and great animal biomass, which reached 10 kg m^-2 in gasohydrothermal fields. They obtain sufficient energy from primary production of microphy-tobenthos, algobacterial, and bacterial mats. Bcnthic species dominant in the bight were not found off the Ushishir Islands.
Some species of macrobenthos inhabiting the Kraternaya Bight differ markedly in size and biomass from the same species found beyond the bight.     

Dynamics of an elastically moored floating body by the three-dimensional infinite element method

The three-dimensional problem of the dynamics of a moored floating object under the action of regular waves is solved numerically as a boundary value problem by use of the finite-infinite element method. The cross-sectional shape of the floating body and the mooring arrangements may all be arbitrary. The mathematical formulations of the problem and procedures of the numerical method are presented in this paper. A corresponding computer program WALOAD has been developed, which is capable of computing wave forces on fixed and floating structures. Numerical computations using this program could give very accurate results, even though rather coarse meshes were used. The program is easy to use and is readily applicable in many practical situations.     

Aquatic surface microlayer contamination in chesapeake bay

The aquatic surface microlayer (SMIC), 50 μm thick, serves as a concentration point for metal and organic contaminants that have low water solubility or are associated with floatable particles. Also, the eggs and larvae of many fish and shellfish species float on, or come in contact with, the water surface throughout their early development. The objectives of this study were (1) to determine the present degree of aquatic surface microlayer pollution at selected sites in Chesapeake Bay, and (2) to provide a preliminary evaluation of sources contributing to any observed contamination.Twelve stations located in urban bays, major rivers, and the north central bay were sampled three times, each at 5-day intervals during May 1986. Samples of 1.4–4.1 each were collected from the upper 30–60-μm water surface (surface microlayer, SMIC) using a Teflon-coated rotating drum microlayer sampler. One sample of subsurface water was collected in the central bay.At all stations, concentrations of metals, alkanes, and aromatic hydrocarbons in the SMIC were high compared with one bulk-water sample and with typical concentrations in water of Chesapeake Bay and elsewhere. SMIC contamination varied greatly among the three sampling times, but high mean contaminant levels (total polycyclic aromatic hydrocarbons, 1.9–6.2 μg 1⁻¹; Pb, 4.9–24 μg 1⁻¹; Cu, 4–16 μg 1⁻¹; and Zn, 34–59 μg 1⁻¹) were found at the upper Potomac and northern bay sites. Three separate areas were identified on the basis of relative concentrations of different aromatic hydrocarbons in SMIC samples - the northern bay, the Potomac River, and the cleaner southern and eastern portions of the sampling area.Suspected sources of surface contamination include gasoline and diesel fuel combustion, coal combustion, and petroleum product releases. Concentrations of metals and hydrocarbons, at approximately half the stations sampled, are sufficient to pose a threat to the reproductive stages of some fish and shellfish. Sampling and analysis of the surface microlayer provides a sensitive tool for source identification and monitoring of potentially harmful aquatic pollution.     

冲绳海槽中部玄武岩的岩石学和地球化学研究

1992年冲绳海槽地质调查时,在134站(126°56′7″E,27°30′0″N)共采集到3件玄武岩样品,其中1件取自134站表层样,另外2件取自134站柱状样中的118-143cm处和193- 218cm处(刀口位置)。通过对上述3件玄武岩样品的岩相学、岩石化学组成、稀土元素和微量元素和锶同位素比值分析研究,认为本区玄武岩具多期次喷发特征,早期喷发形成的玄武岩中单斜辉石质量分数较低,晚期喷发形成的玄武岩中单斜辉石质量分数相对较高,表明了单斜辉石为晚期结晶堆积产物。本区玄武岩稀土配分模式与岛弧拉斑玄武岩基本一致,其87Sr与86Sr质量分数比值m(87Sr)/m(86Sr)为0.7046,亦与岛弧拉斑玄武岩相当。最后利用Rb-Sr丰度特征确定本区的地壳厚度为19-24 km。