Hydrodynamic derivatives and motion response of a submersible surface ship in unbounded water     

Michio Ueno 《Ocean Engineering》2010,37(10):879-890

A submersible surface ship (SSS) is based on a novel concept that the SSS goes on surface like conventional ships in moderate seas but goes underwater in rough seas to the depth sufficient to avoid wave effects. The SSS has a wing system that produces downward lift to go underwater with preserving the residual buoyancy for its safety. The SSS is expected to be able to keep both safety and punctuality even if it encounters unexpected bad weather.The motion of the SSS is studied. The equations of motion are formulated and the procedures for estimating hydrodynamic derivatives are presented. The hydrodynamic derivatives are estimated for a SSS having a configuration, a hull with a pair of main wings and a pair of horizontal tail wings. Using these estimated hydrodynamic derivatives, calculation of the SSS motion is carried out.The calculation results show some specific aspects of the SSS especially for effects of the elevator of main wings and horizontal tail wings, aileron of main wings, rudder and propeller revolution. It is confirmed that the existence of static roll restoring moment and having large hull comparing with wing area play important roles in the motion of the SSS.  相似文献   

Calculation methods and the distribution of anthropogenic variations of pH values in the Pacific Subarctic     

A. G. Andreev  C. -T. A. Chen  S. Watanabe 《Oceanology》2009,49(3):418-428

Common approaches were used to calculate the anthropogenic CO₂, equations were proposed to characterize anthropogenic variations in pH values (ΔpH_ant) in the Pacific Subarctic. For the treated area, the temporal and spatial ΔpH_ant variability was analyzed in 1986 and 2001–2004. From the ΔpH_ant values, the influence of pH variations on iron solubility in seawater was considered.  相似文献   

Habitat selection of stone and starry flounders in an estuary in relation to feeding and survival     

Takeshi Tomiyama  Michio Omori 《Estuarine, Coastal and Shelf Science》2008,79(3):475-482

Juveniles of both stone flounder Platichthys bicoloratus and starry flounder Platichthys stellatus utilize estuaries as nursery grounds. To understand their habitat selection and the functions of habitats such as food supply, we defined the seasonal distribution of recently settled fish of these species in shallow nursery areas and investigated their feeding habits in the Natori River estuary, Japan. Distribution of stone flounder was limited to the lower estuary (<3 km upriver from the mouth) and stone flounder were most abundant near the mouth. Recently settled starry flounder were first detected further upstream in areas characterized by low salinity <10 and by the absence of the predatory sand shrimp Crangon uritai. Early juvenile stone and starry flounders consumed mainly siphons of the bivalve Nuttallia olivacea and the mysid Neomysis awatschensis, respectively; however, 1- and 2-yr-old fish of both stone and starry flounders fed mainly on the bivalve siphons. These results indicate that habitat selections of juvenile stone and starry flounders enable utilization of preferred prey and predator avoidance, respectively, and that non-overlap of these species' habitats results in avoidance of inter-specific competition for food between these two species.  相似文献   

Time series of carbonate system variables off Otaru coast in Hokkaido, Japan     

Ai Sakamoto  Yutaka W. Watanabe  Masato Osawa  KazuoKido  Shinichiro Noriki 《Estuarine, Coastal and Shelf Science》2008,79(3):377-386

We report several biogeochemical parameters (dissolved inorganic carbon (DIC), total alkalinity (TA), dissolved oxygen (DO), phosphate (PO₄), nitrate + nitrite (NO₃ + NO₂), silicate (Si(OH)₄)) in a region off Otaru coast in Hokkaido, Japan on a “weekly” basis during the period of April 2002–May 2003. To better understand the long-term temporal variations of the main factors affecting CO₂ flux in this coastal region and its role as a sink/source of atmospheric CO₂, we constructed an algorithm of DIC and TA using other hydrographic properties. We estimated the CO₂ flux across the air–sea interface by using the classical bulk method. During 1998–2003 in our study region, the estimated fCO_2sea ranged about 185–335 μatm. The maximum of fCO_2sea in the summer was primarily due to the change of water temperature. The minimum of fCO_2sea in the early spring can be explained not only by the change of water temperature but also the change of nutrients and chlorophyll-a. To clarify the factors affecting fCO_2sea (water temperature, salinity, and biological activity), we carried out a sensitivity analysis of these effects on the variation of fCO_2sea. In spring, the biological effect had the largest effect for the minimum of fCO_2sea (40%). In summer, the water temperature effect had the largest effect for the maximum of fCO_2sea (25%). In fall, the water temperature effect had the largest effect for the minimum of fCO_2sea (53%). In winter, the biological effect had the largest effect for the minimum of fCO_2sea (35%).We found that our study region was a sink region of CO₂ throughout a year (−0.78 mol/m²/yr). Furthermore, we estimated that the increase of fCO_2sea was about 0.56 μatm/yr under equilibrium with the atmospheric CO₂ content for the period 1998–2003, with the temporal changes in the variables (T, S, PO₄) on fCO_2sea, thus as the maximum trend of each variable on fCO_2sea was 0.22 μatm/yr, and the trend of residual fCO₂ including gas exchange was 0.34 μatm/yr. This result suggests that interaction among variables would affect gas exchange between air and sea effects on fCO_2sea. We conclude that this study region as a representative coastal region of marginal seas of the North Pacific is special because it was measured, but there is no particular significance in comparison to any other area.  相似文献   

A slow mode wave as a possible source of Pi 2 and associated particle precipitation: a case study     

O. Saka  O. Watanabe  K. Okada  D. N. Baker 《Annales Geophysicae》1999,17(5):674-681

An intensification of auroral luminosity referred to as an auroral break-up often accompanies the onset of geomagnetic pulsation (Pi 2) at the dip-equator. One such auroral break-up occurred at 2239 UT on 16 June, 1986, being accompanied by weak substorm activity (AE≈50 nT) which was recorded in all-sky image of Syowa Station, Antarctica (66.2°S, 71.8°E in geomagnetic coordinates). The associated Pi 2 magnetic pulsation was detected by a fluxgate magnetometer in the afternoon sector at the dip-equator (Huancayo, Peru; 1.44°N, 355.9° in geomagnetic coordinates; 12.1°S, 75.2°W in geographic coordinates; L = 1.00). In spite of the large separation of the two stations in longitude and latitude, the auroral break-up and subsequent luminosity modulation were seen to be correlated with the wave form of the ground Pi 2 pulsation. This occurred in such a way that the luminosity maximum was seen to occur at the phase of maximum amplitudes of Pi 2 wave form. We argue that the observed correlation could be interpreted as indicating a Pi 2-modulation of a field-aligned acceleration of the low energy electrons that may occur near the equator of the midnight magnetosphere.  相似文献   

日本琵琶湖中微囊藻水华形成机理的再认识     

Antonio Quesa  Jean-Jacques Frenette  早川和秀  熊谷道夫 《湖泊科学》1998,10(S1):341-345

Blooms of cyanobacteria are responsible for many problems in freshwater ecosystems. The massive growth of these microorganisms may limit the utilization of freshwater for human requirements since, apart from other problems, the production of toxic substances has been found to occur frequently during blooming periods. Ecologically, cyanobacterial blooms can modify dramatically the ecosystem through their low edibility within the food web and the huge primary production. Thus, saprobic processes are stimulated and the characteristics related to anaerobic conditions are also more extreme.Cyanobacterial blooms are many times explained as the consequence of the eutrophication of waterbodies. However, factors promoting bloom formation and ecological succession of cyanobacteria are not well understood yet.  相似文献   

Early Miocene metallogenic event formed the Bosawa low‐sulfidation epithermal gold deposit,Northeast Japan arc     

Teruhiro Suzuki  Shota Satori  Yuho Fujimaki  Yasushi Watanabe 《Resource Geology》2020,70(4):378-388

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Energetics of wind-induced turbulent mixing in the ocean     

Michio Watanabe  Toshiyuki Hibiya 《Journal of Oceanography》2008,64(1):131-140

The pattern and magnitude of the global ocean overturning circulation is believed to be strongly controlled by the distribution of diapycnal diffusivity below 1000 m depth. Although wind stress fluctuation is a candidate for the major energy sources of diapycnal mixing processes, the global distribution of wind-induced diapycnal diffusivity is still uncertain. It has been believed that internal waves generated by wind stress fluctuations at middle and high latitudes propagate equatorward until their frequency is twice the local inertial frequency and break down via parametric subharmonic instabilities, causing diapycnal mixing. In order to check the proposed scenario, we use a vertically two-dimensional primitive equation model to examine the spatial distribution of “mixing hotspots” caused by wind stress fluctuations. It is shown that most of the wind-induced energy fed into the ocean interior is dissipated within the top 1000 m depth in the wind-forced area and the energy dissipation rate at low latitudes is very small. Consequently, the energy supplied to diapycnal mixing processes below 1000 m depth falls short of the level required to sustain the global ocean overturning circulation.  相似文献   

Characteristics of water mass under the surface mixed layer in Tsushima Straits and the southwestern Japan Sea in autumn   总被引：1，自引：0，他引：1  

Tetsutaro Takikawa  Akihiko Morimoto  Goh Onitsuka  Atsushi Watanabe  Masatoshi Moku 《Journal of Oceanography》2008,64(4):585-594

Two different cold waters were found under the surface mixed layer in Tsushima Straits and the southwestern Japan Sea in autumn 2004. One is cold saline water with a low concentration of dissolved oxygen, and the other is cold less saline water with a high concentration of dissolved oxygen. The older saline water originates from the bottom of the East China Sea, strongly influenced by the Kuroshio water with high salinity. The bottom density in the eastern channel of the Tsushima Straits is coincident with that of the East China Sea in autumn, corresponding to the season when the cold saline water was frequently found in the Tsushima Straits. The newer less saline water originates from the front of Tsushima Warm Current between the Tsushima Warm Current water and the surface cold water in the Japan Sea. This water is formed by subduction above the isopycnal surface from the front of the Tsushima Warm Current.  相似文献   

East-west distribution of POC fluxes estimated from <Superscript>234</Superscript>Th in the northern North Pacific in autumn     

Hajime Kawakami  Makio C. Honda  Kazuhiko Matsumoto  Tetsuichi Fujiki  Shuichi Watanabe 《Journal of Oceanography》2010,66(1):71-83

Observations of primary productivity, ²³⁴Th, and particulate organic carbon (POC) were made from west to east across the northern North Pacific Ocean (from station K2 to Ocean Station Papa) during September–October 2005. Primary productivities in this region varied longitudinally from approximately 236 to 444 mgC m⁻²d⁻¹ and clearly indicate the West High East Low (WHEL) trend. We estimated east-west variations in the POC flux from the surface layer (0–100 m) by using ²³⁴Th as a tracer. POC fluxes in the western region (44–53 mgC m⁻²d⁻¹) were higher than those in the eastern region (21–34 mgC m⁻²d⁻¹). However, the export ratios (e-ratios) ranged from approximately 8% to 16% and did not show the WHEL trend. Contrary to our expectation, no relation between POC flux (or e-ratio) and diatom biomass (or dominance) was apparent in autumn in the northern North Pacific.  相似文献