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141.
Volume transport of the Soya Warm Current revealed by bottom-mounted ADCP and ocean-radar measurement 总被引:2,自引:2,他引:0
Yasushi Fukamachi Iori Tanaka Kay I. Ohshima Naoto Ebuchi Genta Mizuta Hideo Yoshida Shiro Takayanagi Masaaki Wakatsuchi 《Journal of Oceanography》2008,64(3):385-392
The vertical structure of the Soya Warm Current (SWC) was observed by a bottom-mounted acoustic Doppler current profiler (ADCP)
in the region of the SWC axis near the Soya Strait during a 1-year period from May 2004. The ADCP data revealed a marked seasonal
variability in the vertical structure, with positive (negative) vertical shear in summer and fall (winter and spring). The
volume transport of the SWC is estimated on the basis of both the vertical structure observed by the ADCP and horizontal structure
observed by the ocean radars near the strait. The transport estimates have a minimum in winter and a maximum in fall, with
the yearly-averaged values in the range of 0.94–1.04 Sv (1 Sv = 106 m3 s−1). These lie within a reasonable range in comparison to those through other straits in the Japan Sea. 相似文献
142.
143.
Naoki Yoshida † Ravi K. Sheth Antonaldo Diaferio 《Monthly notices of the Royal Astronomical Society》2001,328(2):669-677
We use numerical simulations of a (480 Mpc h −1 )3 volume to show that the distribution of peak heights in maps of the temperature fluctuations from the kinematic and thermal Sunyaev–Zeldovich (SZ) effects will be highly non-Gaussian, and very different from the peak-height distribution of a Gaussian random field. We then show that it is a good approximation to assume that each peak in either SZ effect is associated with one and only one dark matter halo. This allows us to use our knowledge of the properties of haloes to estimate the peak-height distributions. At fixed optical depth, the distribution of peak heights resulting from the kinematic effect is Gaussian, with a width that is approximately proportional to the optical depth; the non-Gaussianity comes from summing over a range of optical depths. The optical depth is an increasing function of halo mass and the distribution of halo speeds is Gaussian, with a dispersion that is approximately independent of halo mass. This means that observations of the kinematic effect can be used to put constraints on how the abundance of massive clusters evolves, and on the evolution of cluster velocities. The non-Gaussianity of the thermal effect, on the other hand, comes primarily from the fact that, on average, the effect is larger in more massive haloes, and the distribution of halo masses is highly non-Gaussian. We also show that because haloes of the same mass may have a range of density and velocity dispersion profiles, the relation between halo mass and the amplitude of the thermal effect is not deterministic, but has some scatter. 相似文献
144.
145.
The distribution of inorganic nitrogen compounds and the metabolic rates of these compounds by microorganisms as a whole were investigated in the Seas of Hiuchi and Bingo. The results obtained are as follows:
- Of inorganic nitrogen compounds, the contents in sea water, those in bottom muds, the uptake or liberation rates of microorganisms as a whole in sea water, and the liberation rates from bottom muds to sea water are 0.2~4.0 μg at. N/l, 3~60 μg at.N/100 g, 0.01~0.5 μg at.N//lhr, and 0.3~1.9 μg at.N/100 cm2/hr, respectively, and these contents or rates of ammonia usually are the largest of these inorganic nitrogen compounds.
- From the above-mentioned results and the others, it is suggested that the nitrogen in the seas circulates mainly in sea water itself and the course of nitrogen cycle, which passes through bottom muds, is not so important, and further that, of the cycle of inorganic nitrogen compounds, the main course is the course which ammonia is liberated from organic nitrogen compounds and it is immediately uptaked by microorganisms, and the course which it is oxidized to nitrate and the others are not so important.
146.
A joint element is proposed, which can simulate the three phases of behaviour of an impermeable layer over a liquefied sand layer. The analysis tracks the post-liquefaction reconsolidation of the sand, the simultaneous development of a water film between the layers and the settlements resulting from the subsequent drainage of the water film. The element is incorporated in a finite element program, which can be used to simulate the behaviour of layered systems. The effectiveness of the program is demonstrated by simulation of the performance of a model soil deposit of two layers in a centrifuge test. 相似文献
147.
M. Endo R. Fujii Y. Ogawa S. C. Buchert S. Nozawa S. Watanabe N. Yoshida 《Annales Geophysicae》2000,18(2):170-181
We have determined the MLT distribution and KpKP dependence of the ion upflow and downflow of the thermal bulk oxygen ion population based on a data analysis using the EISCAT VHF radar CP-7 data obtained at Tromsø during the period between 1990 and 1996: (1) both ion upflow and downflow events can be observed at any local time (MLT), irrespective of dayside and nightside, and under any magnetic disturbance level, irrespective of quiet and disturbed levels; (2) these upflow and downflow events are more frequently observed in the nightside than in the dayside; (3) the upflow events are more frequently observed than the downflow events at any local time except midnight and at any KP level and the difference of the occurrence frequencies between the upflow and downflow events is smaller around midnight; and (4) the occurrence frequencies of both the ion upflow and downflow events appear to increase with increasing KP level, while the occurrence frequency of the downflow appears to stop increasing at some KP level 相似文献
148.
149.
Transient changes in the permeability of fractures in systems driven far‐from‐equilibrium are described in terms of proxy roles of stress, temperature and chemistry. The combined effects of stress and temperature are accommodated in the response of asperity bridges where mineral mass is mobilized from the bridge to the surrounding fluid. Mass balance within the fluid accommodates mineral mass either removed from the flow system by precipitation or advection, or augmented by either dissolution or advection. Where the system is hydraulically closed and initially at equilibrium, reduction in aperture driven by the effects of applied stresses and temperatures will be augmented by precipitation on the fracture walls. Where the system is open, the initial drop in aperture may continue, and accelerate, where the influent fluid is oversaturated with respect to the equilibrium mineral concentration within the fluid, or may reverse, if undersaturated. This simple zero‐dimensional model is capable of representing the intricate behavior observed in experiments where the feasibility of fracture sealing concurrent with net dissolution is observed. This zero‐order model is developed as a constitutive model capable of representing key aspects of changes in the transport parameters of the continuum response of fractured media to changes in stress, temperature and chemistry. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
150.
Triassic to Early Jurassic (c. 200 Ma) UHP metamorphism in the Central Rhodopes: evidence from U–Pb–Th dating of monazite in diamond‐bearing gneiss from Chepelare (Bulgaria) 下载免费PDF全文
I. Petrík M. Janák N. Froitzheim N. Georgiev K. Yoshida V. Sasinková P. Konečný S. Milovská 《Journal of Metamorphic Geology》2016,34(3):265-291
Evidence for ultrahigh‐pressure metamorphism (UHPM) in the Rhodope metamorphic complex comes from occurrence of diamond in pelitic gneisses, variably overprinted by granulite facies metamorphism, known from several areas of the Rhodopes. However, tectonic setting and timing of UHPM are not interpreted unanimously. Linking age to a metamorphic stage is a prerequisite for reconstruction of these processes. Here, we use monazite in diamond‐bearing gneiss from Chepelare (Bulgaria) to date the diamond‐forming UHPM event in the Central Rhodopes. The diamond‐bearing gneiss comes from a strongly deformed, lithologically heterogeneous zone (Chepelare Mélange) sandwiched between two migmatized orthogneiss units, known as Arda‐I and Arda‐II. Diamond, identified by Raman micro‐spectroscopy, shows the characteristic band mostly centred between 1332 and 1330 cm?1. The microdiamond occurs as single grains or polyphase diamond + carbonate inclusions, rarely with CO2. Thermodynamic modelling shows that garnet was stable at UHP conditions of 3.5–4.6 GPa and 700–800 °C, in the stability field of diamond, and was re‐equilibrated at granulite facies/partial melting conditions of 0.8–1.2 GPa and 750–800 °C. The texture of monazite shows older central parts and extensive younger domains which formed due to metasomatic replacement in solid residue and/or overgrowth in melt domains. The monazite core compositions, with distinctly lower Y, Th and U contents, suggest its formation in equilibrium with garnet. The U–Th–Pb dating of monazite using electron microprobe analysis yielded a c. 200 Ma age for the older cores with low Th, Y, U and high La/Nd ratio, and a c. 160 Ma age for the dominant younger monazite enriched in Th, Y, U and HREE. The older age of c. 200 Ma is interpreted as the timing of UHPM, whereas the younger age of c. 160 Ma as granulite facies/partial melting overprint. Our results suggest that UHPM occurred in Late Triassic to Early Jurassic time, in the framework of collision and subduction of continental crust after the closure of Paleotethys. 相似文献