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11.
Weakening of the upper portion of the Japan Sea Proper Water formation was detected based on the dissolved oxygen concentration and potential temperature from 1970 to 2004, unlike the suggestion of previous studies that it has been enhanced since the 1970s. The revealed warming and decreasing trends in DO concentration throughout the water column indicate that the conveyor belt system in the Japan Sea is still slowing down even in the intermediate layers, though a relatively active dissolved oxygen supply into the intermediate layers is suggested. This fact leads us to modify the previous concept about the water mass formation; though a relatively active formation of the intermediate water mass occurs, the deep water formation is not counterbalanced by the intermediate water formation, and the overall Japan Sea Proper Water formation has been stagnating since the 1970s. 相似文献
12.
Yuzo Obara Tomoharu Nakayama Katsuhiko Sugawara Toshiro Aoki Hyun Kuk Jang 《国际地质力学数值与分析法杂志》1992,16(10):701-716
A two-dimensional hybrid method for solving elastoplastic problems in engineering is presented by coupling two existing methods, namely, the boundary element method and the characteristics method. The formulation of this method is presented, as well as an excellent procedure for the determination of the boundary between elastic and plastic regions. It is shown not only that this method is a powerful and accurate method for evaluating the shape and extent of the plastic region around rock caverns, which is of prime importance for the construction of rock caverns, but also applicable to a given range of the initial stress field ratio where only compressive failure occurs. Then, some typical examples are solved in order to check the accuracy of the solution by this method. Furthermore, its successful applications are presented and discussed to determine the shape and the extent of the plastic regions around parallel, circular and rectangular openings. 相似文献
13.
Xiaodong Lai Kazuhiro Norisuye Michi Mikata Tomoharu Minami Andrew R. Bowie Yoshiki Sohrin 《Marine Chemistry》2008,111(3-4):171-183
The distribution of dissolved (D) and acid-dissolvable (AD) Fe, Ni, Cu and Pb in the upper water column (0–300 m depth) was determined in the Australian sector of the Southern Ocean (140°E meridian) during three cruises conducted between November 2001 and March 2002. For Ni and Cu, there was no significant difference in concentration between dissolved and acid-dissolvable species. DNi and DCu showed significant (P = 0.01) positive correlations with silicate, phosphate and nitrate, reflecting their strong nutrient-type behaviour. For Fe and Pb, the acid-dissolvable concentration mostly exceeded the dissolved concentration, reflecting the importance of labile particulate species for these elements. DPb decreased between January and February in the Polar Frontal Zone and in Antarctic continental shelf water. ADPb maxima occurred in the Antarctic Zone, resulting in a maximum AD/D ratio of 7. The mean DFe concentration in the surface mixed layer was 0.3 nM in the sub-Antarctic zone, 0.4 nM in the Polar Frontal Zone, 0.5 nM in the Antarctic Zone and increased southward beyond the Antarctic Divergence and towards the continent. DFe did not show a clear temporal change in its horizontal distribution, which was in contrast to the other nutrients and trace metals. ADFe substantially increased in Antarctic continental shelf water where the AD/D ratio reached 11. The following conclusions can be drawn from these data. (1) Ni and Cu exist exclusively as dissolved species and their distributions are mainly controlled by their biogeochemical cycling, similar to those of the major nutrients. (2) Pb is dominated by particulate species. The distribution of DPb is temporally and spatially variable due to a sporadic source and strong scavenging. (3) DFe is rather a minor fraction of total Fe in Antarctic continental shelf water where shelf sediments and Antarctic sea-ice appear to be strong sources for Fe. There is substantial temporal variation in the supply of Fe to the upper water column. DFe in the mixed layer of the open Southern Ocean is maintained at low concentrations throughout summer due to uptake by phytoplankton and scavenging. 相似文献
14.
Spatiotemporal characteristics of interannual temperature variations in the Tsushima Strait are investigated on the basis
of historical hydrographic data applying the same procedures as Senjyu et al. (2006). Empirical orthogonal function (EOF) analysis revealed that the most energetic mode of variation (the EOF first mode),
which accounts for about 31.5% of the total variance, is the in-phase temperature change for the entire strait. The wintertime
temperature variation described by the first mode is associated with the wintertime heat flux in the northern East China Sea,
while they are poorly correlated in other seasons. The large standard deviation in the time coefficient of the first mode
in August suggests a relationship with the horizontal heat advection in summer in the northern East China Sea. On the other
hand, the EOF second mode, which explains about 12.6% of the total variance, is associated with the stratification and baroclinicity
in the strait. The time coefficient of the EOF second mode negatively correlates with the baroclinic volume transport through
the strait in summer. Comparison of temporal variations among the leading EOF modes for temperature and salinity shows no
significant correlations. This indicates that the principal modes of variation in temperature and salinity vary independently
within an interannual timescale. 相似文献
15.
Ken’ichi Nomoto Keiichi Maeda Masaomi Tanaka Tomoharu Suzuki 《Astrophysics and Space Science》2011,336(1):129-137
The connection between long Gamma Ray Bursts (GRBs) and Supernovae (SNe) have been established through the well observed cases.
These events can be explained as the prompt collapse to a black hole (BH) of the core of a massive star (M≳40M
⊙). The energies of these GRB-SNe were much larger than those of typical SNe, thus these SNe are called Hypernovae (HNe). The
case of SN 2006aj/GRB060218 appears different: the GRB was weak and soft, being called an X-Ray Flash (XRF); the SN is dimmer
and has very weak oxygen lines. The explosion energy of SN 2006aj was smaller, as was the ejected mass. In our model, the
progenitor star had a smaller mass than other GRB-SNe (M∼20M
⊙), suggesting that a neutron star (NS) rather than a BH was formed. If the nascent NS was strongly magnetized as a magnetar
and rapidly spinning, it may launch a weak GRB or an XRF. The peculiar light curve of Type Ib SN 2005bf may also be powered
by a magnetar. The blue-shifted nebular emission lines of 2005bf indicate the unipolar explosion possibly related to standing
accretion shock instability (SASI) associated with a newly born NS. 相似文献
16.
Journal of Oceanography - The flow field in the Toyama Deep-Sea Channel (TDSC) in the Japan Sea was investigated based on mooring observations. An asymmetric current system accompanying offshore... 相似文献
17.
Atsushi Kaneda Kouta Ayukawa Naoki Hirose Jun Tsuzuki Yutaka Kumaki Tomoharu Senjyu Yosuke Igeta Tatsuro Watanabe 《Journal of Oceanography》2017,73(2):181-192
A sudden strong coastal current called a “kyucho” occurred in August 2013 in the eastern coastal waters of Wakasa Bay, Japan. This study examined its characteristics based on both observational data collected by intensive field investigations and the simulation results of a numerical model. The field investigations comprised moored buoy observations near the coast and voyages by a research vessels and fishing boats. The mooring observations indicated that a current speed exceeding 50 cm s?1 occurred abruptly near the eastern coast of the bay, in association with a synchronous change in the current direction. Data collected by acoustic Doppler current profilers (ACDPs) mounted on the vessels showed that a clockwise eddy existed in the bay and that the current on the east side of the eddy generated the kyucho near the coast. Based on the results of the numerical model and the analysis of the ADCP data, it was considered that the clockwise eddy was generated by a strong current at the tip of the Tango Peninsula, in the western part of the bay. As the eddy propagated from west to east across the bay, it induced the kyucho in the coastal waters in the east of the bay. 相似文献
18.
19.
The Fe2+–Mg distribution coefficients between sapphirine and spinel:were experimentally determined at pressures of 9–13 kbar and temperatures of 950–1150 °C using a natural ultrahigh-temperature (UHT) granulite with paragenesis of these minerals from the Napier Complex in East Antarctica [XMg = Mg / (Fe + Mg); XFe = Fe / (Fe + Mg)]. A new sapphirine–spinel geothermometer has been obtained as:
We applied the exchange thermometer to UHT or high-grade metamorphic rocks that were reported from various complexes in the world. If the KD values of 2.63–4.34 obtained from low-Cr mineral pairs such as XCrSpr < 0.016 and XCrSpl < 0.047 were substituted into the equation, their temperature conditions would be estimated as 806–1050 °C at 11 kbar. The XCr means Cr / (Al + Cr(+ Fe3+)). These temperatures are reasonable retrograde or near peak metamorphic condition. 相似文献
20.
The upper portion of the Japan Sea Proper Water; Its source and circulation as deduced from isopycnal analysis 总被引：1，自引：0，他引：1
All of the available hydrographic station data (temperature, salinity, dissolved oxygen, phosphate and nitrate) taken in various seasons from 1964 to 1985 are analyzed to show where the upper portion of the Japan Sea Proper Water (UJSPW) is formed and how it circulates. From vertical distributions of water properties, the Japan Sea Proper Water can be divided into an upper portion and a deep water at the 1 (potential density referred to 1000 db) depth of 32.05 kg m–3 surface. The UJSPW in the north of 40°N increases in dissolved oxygen contents and decreases in phosphate contents in winter, while no significant seasonal variation is seen in the south of 40°N. Initial nutrient contents calculated from relationships between AOU and nutrients on isopycnal surfaces show no significant regional difference in the Japan Sea; this suggests that the UJSPW has originated from a single water mass. From depth, dissolved oxygen and phosphate distributions on 1 32.03 kg m–3 surface, core thickness distribution and subsurface phosphate distribution, it is inferred that the UJSPW is formed by the wintertime convection in the region west of 136°E between 40° and 43°N, and advected into the region west of the Yamato Rise along the Continent; finally, it must enter into the Yamato Basin. 相似文献