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81.
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
82.
During mountain torrents, large-magnitude floods may result from heavy rainfall and cause the breakage of landslide dams naturally formed by heavy rainfall, earthquakes, and so on. The characteristics of longitudinal spreading of clear water discharge and changes in flow depth must be clarified because the changes in peak depth have not yet been examined in steep-slope torrents and because there are few data on spreading of flash floods and related sedimentation in mountainous torrents. In the present study, experimental data were collected through hydraulic model tests over a rigid bed, and the spreading of water, fine sediment, bed load, and large boulders due to flooding are discussed assuming that flash flooding/debris flows occur in the upstream reach. The effects of changes in flow width, such as expansions and contractions in the flow width, as well as changes in meandering channels, sediment transportation, and spreading flow depth resulting from bores are examined using flume data for a steep-slope torrent. The data obtained in the present study reveal that fine sediment components are transported to the downstream reach if large-magnitude floods occur and that the spreading rate and peak lags of the fine sediment and water level indicate the occurrence of a flood in the upstream reach. 相似文献
83.
Journal of Geographical Sciences - The North China Plain is one of the most water-stressed areas in China. Irrigation of winter wheat mainly utilizes groundwater resources, which has resulted in... 相似文献
84.
The Kamiomi, Sashima-gun (Iwai-shi), Ibaraki-ken, Japan, chondrite (observed to fall in spring, during the period 1913–6), consists of olivine, orthopyroxene, nickel-iron and troilite with minor amount of plagioclase, clinopyroxene, apatite and chromite. The average molar composition of olivine (Fa19) and orthopyroxene (Fs17) indicates that Kamiomi is a typical olivine bronzite chondrite. From the well-recrystallized texture, the presence of poorly-definable chondrules, homogeneous composition of olivine and absence of glass, this chondrite could be classified in petrologic type 5. The bulk chemical composition, especially, total Fe (27.33%) and metallic Fe (17.00%) as well as Fetotal/SiO2(0.72), Femetal/Fetotal (0–633) and SiO2/MgO (1.59) support the above conclusion. Coexistence of heavily-shocked olivine grains in the matrix composed of olivines and pyroxenes which suffered from light to moderate shock effect suggest that impacting phenomena, small-scaled but locally strong, occurred on the Kamiomi parent body. 相似文献
85.
Hiroyasu Ando Takeshi Noguchi Masao Nakagiri Akihiko Miyashita Yasumasa Yamashita Kyoji Nariai Hiroyoshi Tanabe 《Astrophysics and Space Science》1989,160(1-2):183-189
Two steps have been taken to decide at what place and altitude to set up the JNLT on Mauna Kea. First, the wind tunnel experiment has been made in collaboration with the Institute of Meteorology using the two models of summit area with the reduced scales of 1/1000 and 1/5000. This study tells us that the north-west cone is suitable for JNLT. Secondly, we have done the measurement of the microthermal activities in this area with a 30 m tower, which was continued for about 4 months in collaboration with the University of Hawaii. This experiment has given the mean vertical profile ofC
T
2
over 4 months and its scale height in the boundayr layer on our site. By use of these measurements, the contribution of the boundary layer to seeing is estimated. The behaviour ofC
T
2
under strong winds can be explained very well by topographic effects, which is in fairly good agreement with the results of our wind tunnel experiment.Paper presented at the Symposium on the JNLT and Related Engineering Developments, Tokyo, November 29–December 2, 1988. 相似文献
86.
Akihiko Murakami Tokio Matsuda Nobuhiro Watanabe Shinichi Nagasawa 《Journal of Oceanography》1976,32(5):242-248
The ability to degraden-paraffin mixture of two bacterial strains,Caulobacter sp. andFlavobacterium sp., isolated from sea water of Tokyo Bay was studied experimentally in the enriched seawater (ESW) medium. These bacteria degraded actively the mixture ofn-tridecane,n-tetradecane,n-pentadecane andn-hexadecane. The maximum rate of degradation was observed after a lag period of 2 to 8 day and these bacteria were found to degrade then-paraffin mixture at rates calculated to be in a range from 3.3×10?12 to 3.4×10?11 mg-oil cell?1 h?1 at 20°C. The maximum degradation rate,r m mg-oil l?1 h?1, was correlated with the amount of the initial totaln-paraffin,S mg-oil l?1, as expressed by the following equation: $$rm = (rm)\max \left( {\frac{S}{{S + Km}}} \right)$$ where (r m )max denotes the largest value ofr m whenn-paraffin exists in large excess andK m is a constant and represents the amount ofn-paraffin at which the degradation rate,r m , reaches 1/2 of its largest value, (r m )max. The values of (r m )max andK m were calculated to be as follows: In the case ofCaulobacter sp. (strain KM-1), (r m )max=6.0 mg-oil l?1 h?1 andK m =191 mg-oillesw ?1; in the case ofFlavobacterium sp., (r m )max=5.47 mg-oil l?1 h?1 andK m =152 mg-oillesw ?1. 相似文献
87.
Akihiko Ito Koki Ouchi Isamu Hisa Susumu Seki Yoshio Seto Shoji Kurashina 《Journal of Oceanography》1984,40(2):98-104
In the consideration of safety it is required that packages containing radioactive wastes when dumped at sea should keep their
integrity and retain their contents until they reach the seabed. Packages containing simulated radioactive wastes (non-radioactive)
were tested by a free-fall method at depthsca. 4,300 m in an area for dumping industrial waste off Shikoku Island. Since the weight of the largest package was 4,300 kg,
special attention was paid to the connection of a buoyancy system with mooring rope. Descent and ascent velocities of the
free-fall system were calculated prior to the experiment. A free-fall experiment with an extremely heavy object, heavier than
ever previously reported, was accomplished without trouble by using the free-fall system. Recovery of a camera, flash-light,
and other components was successful in each of the three experiments. Successive photographing of the package during descent
was made and its integrity was observed using the photographs taken by the recovered camera. The packages remained intact
during descent and at least for a short time after arrival on the seabed. 相似文献
88.
Mitsuhiro Toratani Hajime Fukushima Hiroshi Murakami Akihiko Tanaka 《Journal of Oceanography》2007,63(3):525-532
The present study proposes an atmospheric correction scheme for Advanced Earth Observation Satellite II (ADEOS-II)/Global
Imager (GLI) ocean color retrieval that corrects for the atmospheric absorptive aerosol effect. Radiative transfer simulations
were conducted assuming a non-absorptive model aerosol with a soot-type aerosol at various mixture ratios. The results indicate
that while the spectral dependency of aerosol reflectance does not change in the longer (>550 nm) wavelength region, the reflectance
at shorter wavelengths is highly variable and depends on the mixture ratio. The influence of aerosol absorption was also investigated
using GLI data from ocean areas adjacent to Japan in the presence of absorptive Siberian fire smoke aerosol in the spring
of 2003. The spectral curvature of the aerosol was estimated from the data obtained. An empirical, iterative scheme that detects
and evaluates the influence of absorptive aerosols was developed by comparing 380 nm GLI-observed aerosol reflectance with
predicted reflectances derived using an in-water optical model. To evaluate the performance of this scheme, satellite-derived
normalized water-leaving radiances were compared with those measured from a ferry servicing Nagasaki and Fukue. The results
of data acquired on March 20, 2003, indicate that this absorption correction scheme improved root mean square estimation error
for normalized water-leaving radiance by approximately 40% in the 380, 400, and 412 nm bands. This atmospheric correction
algorithm was used as a part of the second version of the GLI standard ocean color data process system at Japan Aerospace
Exploration Agency (JAXA). 相似文献
89.
A simple procedure for fractionation of phosphorus components in natural populations of phytoplankton has been developed. By a combination of a trichloroacetic acid (TCA) extraction, a hot dilute acid treatment, a charcoal treatment and an organic solvent extraction, cellular phosphorus was divided into orthophosphate, nucleotide phosphorus, sugar phosphates, acid-soluble polyphosphates, lipid phosphorus, nucleic acid phosphorus, acid-insoluble polyphosphates, and residual phosphorus. The recovery of phosphorus was 94±5%. This technique was applied to natural populations of phytoplankton in summer surface waters of Tokyo Bay. Nucleic acid phosphorus and orthophosphate were most abundant, and accounted for 30 to 50% of total phytoplankton phosphorus. The nucleic acid phosphorus was proportional to the biomass of phytoplankton, irrespective of ambient nutrient concentrations. The orthophosphate showed the largest change in association with the change in cellular phosphorus content as well as in ambient phosphate. The orthophosphate serves as a phosphorus reserve in the natural populations of phytoplankton in summer surface waters of Tokyo Bay whereSkeletonema costatum was dominant. Acid-insoluble polyphosphates tended to increase when ambient concentration of phosphate was high, but their amounts were almost one order of magnitude lower than that of orthophosphate. 相似文献
90.
Akihiko Kuwahara Tsuneyuki Abe Masayuki Shimono Makoto Kashiwai Masatosi Sinoda 《Journal of Oceanography》1973,29(3):106-112
A pump-sampler was designed to study the distribution of marine plankton and its possible relationship with the temperature and salinity of the water. Sea water was pumped up through a 2 inch diameter hose and plankton contained in it was collected on a filter cup (2 inches in diameter, 139 meshes/inch) without being damaged. The filter cup, when clogged by plankton organisms, was washed by spraying with about 100 cu. cm of water. The differences between two continuous with an interval of more than 3–4 seconds could be detected.A preliminary operation along a 2.82 km course in Maizuru Bay was carried out simultaneously with temperature-salinity measurements at sampling intervals of 30 m. Temperature was measured by a thermistor resistance thermometer, and salinity was measured by a salinometer with a subsample of water which was collected from an additional opening of the pump-sampler. The temperature-salinity record showed that four zones of water were characterized.It was found that wide variation of plankton counts indicated dense concentrations of particular species or group of species, and on the mesoscale it was possible to examine the size of the aggregation. 相似文献