The ADCP on an advanced towed fish with controllable main and tail wings, called DRAKE measured a detailed sectional structure of the Kuroshio flowing to the NE along the East China Sea shelf slope west of Okinawa. At the observation period, a countercurrent directed to the SW formed in near-bottom water on the shelf slope. The horizontal flow perpendicular to the stream axis of the Kuroshio constructed a convergence zone around the boundary between the Kuroshio and the countercurrent. An intensive upwelling with the maximum velocity of 2.8 cm s–1 was found to distribute on the shelf slope around the convergence zone. A dynamic cause of this intensive upwelling is discussed carefully. 相似文献
A multiple sieve system for size separation of preserved copepod specimens was devised and its performance tested. The system provides a useful tool for determining the size composition of the copepod population, since the copepod size distribution (measured as log-prosome length) differed significantly between different sieves and the sieve-specific copepod size frequency distribution could be practically substituted by a normal distribution function. However, the mean copepod size of the same sieve differed between sampling stations due to clogging by materials other than crustacean zooplankton. 相似文献
Six newly developed floats, which were set to drift on the 26.7 σθ isopycnal surface and to profile temperature, salinity and pressure above 1000 dbar once a week, were deployed in the Oyashio
and Kuroshio Extension (KE) in order to examine the circulation, formation site and time scale of newly formed North Pacific
Intermediate Water (NPIW). The floats were deployed in February or May 2001, and the data from their deployments to December
2002 are analyzed here. Four of the six floats were deployed near the KE axis at around the first meander crest, and they
moved eastward to 157°E–176°W at latitudes of 30°N–45°N. The other two floats deployed in the Oyashio water with low-potential
vorticity near the south coast of Hokkaido moved southward to reach the KE front and then moved eastward to the same region
as the first four floats. The temperature and salinity at 26.7 σθ measured by the profiling floats indicate that the source waters of NPIW, Oyashio and Kuroshio waters are drastically mixed
and modified in the mixed water region west of 160°E. The floats were separated into the three paths east of 160°E between
the Kuroshio Extension front and the north of Water-Mass front (nearly subarctic front). New NPIW is judged to be formed along
these three paths since the vertical profiles of temperature and salinity are quite smooth, having a salinity minimum at about
26.7σθ along each path. Kuroshio-Oyashio isopycnal mixing ratios of the new NPIW are 7:3, 6:4 and 5:5 at 26.7σθ along the southern, middle and northern paths, respectively. Potential vorticity converges to about 14–15 × 10−11 m−1s−1 along these paths. The time scale of new NPIW formation is estimated to be 1–1.5 years from the merger of Oyashio and Kuroshio
waters to the formation of the new NPIW.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
Summary A geothermal and meteorological observation was carried out inside a hot tunnel (named Torigoe tunnel) penetrating through a volcanic zone in northeastern Japan, just after it has been penetrated. Rock wall surface temperature, some thermal properties of rock samples, temperature profile in slender pits drilled into the rock body, temperature of water flowing on the floor and the meteorological elements of air passing through the tunnel are contained in the observation.Introducing the coefficient of heat transfer determined from the Reynolds analogy for turbulent forced convection in a circular tube, the heat budget of the air-tunnel system is investigated with those observed data. The results show that the net sensible heat of 58.61 kW is drawn out from the tunnel by air passing through it and seems to be overcompensated by the net heat supply of 67.21 kW from the rock wall to air, while for the net latent heat removal of 101.56 kW by air the apparent undercompensation of 80.01 kW is found from the water flowing on the floor. Consideration is carried out on such excess and deficiency of heat supplies.
Zusammenfassung In einem heißen Tunnel (dem Torigoe-Tunnel), der durch vulkanisches Gebiet im nordöstlichen Japan verläuft, wurden unmittelbar nach Tunneldurchstoß geothermische und meteorologische Untersuchungen durchgeführt. Die Temperatur der Gesteinsoberfläche, spezifische thermische Eigenschaften der Gesteinsproben, das Temperaturprofil von dünnen Bohrkernen, als auch die Temperatur des Wassers am Tunnelgrund und meteorologische Daten der Durchzugsluft werden in dieser Untersuchung berücksichtigt.Durch Einführung des durch die Reynolds-Analogie determinierten Wärmeaustauschkoeffizienten für turbulente, erzwungene Konvektion in einer kreisförmigen Röhre wird der Wärmehaushalt der Luft im Tunnelsystem unter Heranziehung der angeführten Daten untersucht. Die Resultate zeigen, daß 58.61 kW fühlbare Wärme dem Tunnel durch die Luft entzogen werden, die jedoch durch eine Zufuhr von 67.21 kW von der Felswand an die Luft abgegebener fühlbarer Wärme überkompensiert zu werden scheint, während der dauernden latenten Wärmeabfuhr durch die Luft von 101.56 kW eine Unterkompensierung von 80.01 kW durch das am Tunnelgrund fließende Wasser gegenübersteht. Die Folgen dieses Überschusses bzw. Defizites werden genauer diskutiert.
The thermal phase transition of K2SO4 has been investigated by high temperature polarized light microscopy. K2SO4 undergoes a first-order transition at 587° C where the orthorhombic low temperature form (Pmcn) transforms into a hexagonal high temperature modification (P63/mmc). Prior to the beginning of the phase transition, K2SO4 shows an anomalous optical behavior. The crystal apparently becomes optically uniaxial twice at 338° and 425° C, respectively, and truly optically uniaxial at 587° C. The phase transition propagates through an intermediate temperature form, which is sandwiched between the low and the high temperature forms and moves in a definite direction, 〈130〉 (orthorhombic indices), in the vicinity of the phase transition. Passing through the phase transition point on cooling, dark belts crossing each other are observed which are a result of the transformation twins parallel to {110} and {130}. 相似文献
A simple, rheological model is presented for plate motions to explain episodic volcanism and tectonism. A lithospheric plate is modelled by a gliding block and the basal edge of the sinking plate is modelled by a stick-slip-like fault system. The friction force is assumed to have a maximum at a critical sliding velocity. When the sliding velocity at the basalt edge exceeds the critical velocity, the basal edge system becomes unstable and the plate accelerates. Conditions that the model system has a periodic solution are obtained and parameters of the system are evaluated from rheological properties of the mantle and configurations of the plate. Results suggest that a plate moves nearly steadily over a long period of time but it accelerates sharply during a very short period of time. The accelerating period is considered to correspond to the episodes of active volcanism and tectonism. 相似文献
The orthorhombic MgSiO3 perovskite has been synthesized with the aid of a double-stage split-sphere-type high-pressure apparatus at about 280 kbar and 1000°C. The unit cell dimensions are: a = 4.7754(3)Å, b = 4.9292(4)Å and c = 6.8969(5)Å with the probable space group Pbnm. Calculated density is 4.108 g cm?3. Crystal structure determination has been carried out by means of both the geometrical simulation (DLS) technique and the ordinary powder X-ray analysis. The results indicate that the MgSiO3 perovskite is closer to the ideal perovskite than ScAlO3 perovskite. 相似文献
High-pressure phase relations in ZnSiO3 and Zn2SiO4 were investigated at about 1000°C and in the pressure range of 100–500 kbar, using a double-staged split-sphere type of high-pressure apparatus.Clinopyroxene-type ZnSiO3 transforms directly into a polymorph with the ilmenite structure at 120 kbar. The hexagonal unit cell dimensions of the ZnSiO3 ilmenite are determined to be under ambient conditions.The following reactions are also recognized at about 1000°C: and: The stabilities of silicate ilmenites, especially the absence of ilmenite of transition metal silicate composition, is discussed. It is pointed out that data on phase relations in zinc silicates may be informative for the consideration on those in magnesium silicates under very high pressures. It is suggested that the silicate ilmenite may be a major constituent in the lower mantle. 相似文献
Pressure effects on the lattice parameters of β- and γ-Mg2SiO4 have been measured at room temperature and at pressures up to 100 kbar using a multi-anvil high-pressure X-ray diffraction apparatus. The volume changes (ΔV/V0) at 90 kbar are 5.4 · 10?2 and 4.2 · 10?2 for β- and γ-Mg2SiO4, respectively. Isothermal bulk moduli at zero pressure have been calculated from least-square fits of the data to straight lines. They turn out to be 1.66 ± 0.4 and 2.13 ± 0.1 Mbar for β- and γ-Mg2SiO4, respectively. The α → γ transition obeys Wang's linear Vφ?ρ relation but the α → β transition does not. 相似文献
