III-2 A relation between the mooring and the optimum energy conversion of a wave energy converter consisting of two floating bodies     

Masao Kunimoto 《Ocean Engineering》1985,12(6):568

  相似文献   

Possible shrinking of the primary component of epsilon aurigae     

Mamoru Saitō  Masatoshi Kitamura 《Astrophysics and Space Science》1986,122(2):387-393

Radial velocities of the primary star of Aur are presented for phases outside the eclipse between 1975 and 1985. A violent collapse of the atmosphere has occurred with a velocity of about 40 km s^–1 on October 1977, indicating a decrease of 0.07 AU in the radius for three days. A shrinking of the primary star is suggested from the characteristics of eclipse light curves that the duration of totality has become longer and the duration of eclipse shorter from eclipse to eclipse. The decrement of radius is estimated to be about 16%, 0.2 AU, in recent 27 years.  相似文献   

Effect of vertical viscosity and diffusivity on tropical ocean circulation     

Yoshiteru Kitamura  Nobuo Suginohara 《Journal of Oceanography》1987,43(1):1-20

Response of the tropical ocean to a uniform zonal wind is studied numerically and analytically. In addition to the Equatorial Undercurrent and surface westward flows on both sides of the equator, an eastward flow at the pycnocline depth is formed at several degrees latitude in both hemispheres. This subsurface eastward flow first appears in the eastern part of the ocean and extends to the west. Then it gradually decreases in speed, and at a steady state the speed is of the order of 1cm sec^–1. The spatial distribution of this subsurface flow is similar to the Subsurface Countercurrent, but the speed is one order smaller than that observed. The obtained thermostad is obscure compared with that observed. Whole of the time evolution produced by a numerical model can be accounted for by linear wave dynamics in a multi-layer model including vertical diffusion and friction. Although diffusion and friction are essential to maintain this subsurface flow, changes in the values of coefficients for vertical viscosity and diffusivity and also in initial density stratification lead only to a minor change in the speed of the subsurface eastward flow. It is concluded that a subsurface eastward flow with speed exceeding 10 cm sec^–1 accompanied by a distinctive thermostad structure cannot be explained by linear wave dynamics including vertical dissipation.  相似文献   

Abyssal current along the northern periphery of Shikoku Basin     

Masao Fukasawa  Toshihiko Teramoto  Keisuke Taira 《Journal of Oceanography》1986,42(6):459-472

Abyssal currents along the northern periphery of the Shikoku Basin south of Japan were measured by current meters moored off Cape Daio-zaki, Cape Shiono-misaki and Cape Ashizuri-misaki and on the eastern foot of the northernmost part of the Kyushu-Palau Ridge. Total length of observation off Cape Shiono-misaki was about five years including the periods of the Kuroshio large meander and no meander. Analyses of current data show:

1. Mean currents with a magnitude of 5–10 cm sec^?1 were observed during the whole observation period at all of current meters which were set 400 m above the sea bottom that was deeper than 4,500 m. The mean current for each current meter was parallel to the local bottom contour arond each station and was toward a direction looking the Nankai Trough (a trough located along the northern end of the Shikoku Basin) to the left.
2. At each station located above the shelf toe off Cape Daio-zaki and off Cape Shiono-misaki and on the foot of the Kyushu-Palau Ridge, the mean current increases with depth (a bottomward intensification of the mean current), and the vertical extent of the mean current is estimated to be about 2,000 m above the sea bottom.
3. At a station located at 2,600 m depth on the continental slope off Cape Shiono-misaki, no bottom-ward intensification of currents was observed.

These results strongly suggest that a steady abyssal flow exists in the depths deeper than about 3,000 m along the northern and northwestern peripheries of the Shikoku Basin. Existence of the abyssal circulation system is also suggested, at least, in the north of the Shikoku Basin.  相似文献   

A Preliminary Study of Oceanic Bomb Radiocarbon Inventory in the North Pacific during the Last Two Decades     

Yutaka W. Watanabe  Tsuneo Ono  Koh Harada  Masao Fukasawa 《Journal of Oceanography》1999,55(6):705-716

Radiocarbon and total carbonate data were obtained near the 1973 GEOSECS stations in the North Pacific along 30°N and along 175°E between 1993 and 1994. In these stations, we estimated radiocarbon originating from atomic bomb tests using tritium, trichlorofluoromethane and silicate contents. The average penetration depth of bomb radiocarbon during the two decades has deepened from 900 m to 1300 m. Bomb radiocarbon inventories above the average value for the whole North Pacific were found widely in the western subtropical region around 30°N both in the 1970s and 1990s, and its area in the 1990s was broader than that in the 1970s. In most of the North Pacific, while the bomb radiocarbon has decreased above 25.4, the bomb radiocarbon flux below 25.4 was over 1 × 10¹² atom m^-2yr^-1 in the subtropical region around 30°N. In the tropical area south of 20°N, the bomb radiocarbon inventory below 25.4 increased from zero to over 10 × 10¹² atom m^-2 during the last three decades. These distributions suggest that the bomb radiocarbon removed from the surface is currently accumulated with bomb ¹⁴C flux of over 1 × 10¹² atom m^-2yr^-1 below 25.4 in the subtropical region, mainly by advection from the higher latitude, and that part of the accumulated bomb ¹⁴C gradually spread southward with about 30 years.  相似文献   

Hydrographic structure in association with deep boundary current in the north of the Shikoku Basin     

Masao Fukasawa  Toshihiko Teramoto  Keisuke Taira 《Journal of Oceanography》1995,51(2):187-205

High quality CTD data were collected in the north of the Shikoku Basin where an abyssal boundary current has been observed through direct current measurements. Analyses of hydrographic data showed:

1. Colder and saltier water (heavier water) compared to surrounding waters is found above the continental shelf-toe and the eastern flank of the Kyushu-Palau Ridge where the existence of the abyssal boundary current has been expected. The heavier water has a horizontal extent of about 50 km.
2. The heavier water has the vertical scale of 2000 m from the sea bottom, and is associated with a thermal wind shear which enhances a component of the flow toward a direction looking the Nankai Trough (a trough located along the northern end of the Shikoku Basin) to the left in the abyss. The assumed “level of no motion” at about 2500 m depth gives the geostrophically estimated current in a good agreement with the directly measured current.

A volume transport associated with the colder and higher salinity water is estimated to be about 2 Sv off Cape Shiono-misaki which may include a recirculation above the Nankai Trough. This is about twice of the transport estimated in the interior of the Shikoku Basin through a vorticity balance between the stretching term and latitudinal variation of the planetary vorticity.  相似文献   

Constraint of lattice-preferred orientation (LPO) on Vp anisotropy of amphibole-rich rocks     

Keigo Kitamura 《Geophysical Journal International》2006,165(3):1058-1065

  相似文献   

Evapotranspiration from citrus trees growing in sandy soilunder drip irrigation with saline water     

杨胜利  Tomohisa Yano 《中国科学D辑(英文版)》2002,45(Z1)

An experiment on evapotranspiration from citrus trees under irrigation with saline waterwas carried out for 4 months. Two lysimeters planted with a citrus tree in the green house wereused. One lysimeter was irrigated with saline water (NaCl and CaCl2 of 2000 mg/L equivalence,EC = 3.8 dS/m, SAR = 5.9) and the other was irrigated with freshwater using drip irrigation. Theapplied irrigation water was 1.2 times that of the evapotranspiration on the previous day.Evapotranspiration was calculated as the change in lysimeter weight recorded every 30 minutes.The lysimeters were filled with soil with 95.8% sand. The results of the experiment were as follows.(i) The evapotranspiration from citrus tree was reduced after irrigation with saline water. Theevapotranspiration returns to normal after leaching. However it takes months to exhaust the saltfrom the tree. ( ii ) To estimate the impact of irrigation with saline water on the evapotranspirationfrom citrus trees, the reduction coefficient due to salt stress (Ks) was used in this experiment.Evapotranspiration under irrigation with saline water (ETs) can be calculated from evapotranspira-tion under irrigation with freshwater (ET) by the equation ETs = Ks× ET. Ks can be expressed as afunction of ECsw. (iii) The critical soil-water electrical conductivity (ECsw) is 9.5 dS/m, beyondwhich adverse effects on evapotranspiration begin to appear. If ECsw can be controlled at below9.5 dS/m, saline water can be safely used for irrigation.  相似文献   

Kosa (yellow sand) components in precipitation collected at central Japan     

Tetsuji Chohji  Moritsugu Kitamura  Masahiro Tabata 《中国科学D辑(英文版)》2002,45(1):71-77

In east Asia, acidic gases derived from fossil fuel combustion have increased in the past decades. On the other hand, the Asian dust, also called Kosa (yellow sand) is transported following windstorms from arid lands in the Asian continent. Many researchers have been interested in the reaction between acidic aerosols and Kosa aerosols as well as the long-range transport of these emissions. To investigate the characteristics of chemical components in precipitation on a long-term basis over Japan, precipitation was sequentially collected from April 1984 to March 1997 at Kanazawa located near the coast of the Sea of Japan. Precipitation samples were collected at 1 mm intervals for the first 5 mm rainfall and all volume of rainwater after 6 mm for all precipitation events with an automatic wet only precipitation collector. According to the analyses of precipitation including Kosa aerosols during Kosa periods, the reaction in the air between Kosa and acidic components during the long-range transport was discussed.  相似文献   

Bedrock structure in Adapazari, Turkey—a possible cause of severe damage by the 1999 Kociaeli earthquake     

Masao Komazawa  Hitoshi Morikawa  Kajuro Nakamura  Junpei Akamatsu  Keiichi Nishimura  Sumio Sawada  Ayfer Erken  Akin Onalp 《Soil Dynamics and Earthquake Engineering》2002,22(9-12):829-836

The 1999 Kocaeli earthquake brought serious damage to downtown of Adapazari. To study why strong motions were generated at the town, a bedrock structure was investigated on the basis of Bouguer gravity anomaly, and SPAC and H/V analyses of microseisms. It was revealed that, the basin consists of three narrow depressions of bedrock with very steep edges, extending in E–W or NE–SW directions along the North Anatolia faults, and the depth to bedrock reaches 1000 m or more. Downtown of Adapazari is located 1–2 km apart from the basin-edge. It is considered that, the specific configuration of bedrock amplifies ground motions at the downtown area by focusing of seismic waves and/or interference between incident S-waves and surface-waves secondarily generated at the basin-edge. Studying 3D bedrock structure is an urgent issue for microzoning an urban area in a sedimentary basin.  相似文献