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71.
Quartz crystals twinned according to Japan twin law were investigated by means of X-ray topography in order to understand the origin of characteristic morphology of twin crystals. It is demonstrated that the flattened and elongated morphology characteristic of quartz twins is due to preferential growth at twin junctions where dislocations with the Burgers vector direction 〈11 \(\overline {\text{2}} \) 1〉 concentrate, and that such preferential growth operates only when {10 \(\overline {\text{1}} \) 1} faces meet at the twin junction. Once {10 \(\overline {\text{1}} \) 0} faces appear at the twin junction due to the change of growth conditions, the effect diminishes sharply and the characteristic morphology becomes less pronounced. This leads to the conclusion that the characteristic morphology of quartz crystals twinned according to Japan twin law is formed at the earlier stage of growth and becomes less pronounced at the later stage of growth. 相似文献
72.
The annual transport of anthropogenic carbon (Canth) to the North Pacific Intermediate Water (NPIW) from the Western Subarctic Gyre (WSG) has been re-estimated by using newly
estimated Oyashio transport and Canth concentration, the latter calculated by the recently-established “ΔC*” method with some modifications. Estimated annual Canth transport through the nearshore Oyashio west of 146°E was 0.020 ± 0.010 GtC y−1, closely approximating the previous estimation based on a 1-D model calibrated with the CFC vertical distribution. The present
study, however, found that an additional 0.025 ± 0.010 GtC y−1 of Canth was transported into NPIW in the region east of 146°E. Total Canth transport, 0.045 GtC y−1, contributes about 35% of annual Canth accumulation of the whole temperate North Pacific.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
73.
Yugo Shimizu Takanori Iwao Ichiro Yasuda Shin-Ichi Ito Tomowo Watanabe Kazuyuki Uehara Nobuyuki Shikama Toshiya Nakano 《Journal of Oceanography》2004,60(2):453-462
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
74.
Ichiro Yasuda 《Journal of Oceanography》2003,59(4):389-402
The hydrographic structure and variability in the Kuroshio-Oyashio Transition Area of the northwestern Pacific are briefly
reviewed, focusing on the circulation, frontal structure and water-mass formation from surface to intermediate depths. This
area is a key to understanding climate and ecosystem variations because signals can be detected earlier than major climate
regime shifts and also because species replacement among small pelagic fishes could be related to environmental changes in
this area. We need further studies of the effect of North Pacific Intermediate Water on surface currents and frontal structures
and also studies on the formation and variability of water-masses in surface mixed layer.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
75.
The behavior of the isolated vortices over the topographic-is considered with the quasi-geostrophic two-layer model, in the limit of very shallow upper layer, in the absence of planetary-. The results are compared with the observed Kurshio warm-core rings. When a ring drifts southward (northward) relative to the meridional mean current, it radiates (does not radiate) Rossby waves in the lower layer. Even when the lower layer is radiating, the decaying is very slow as long as the ring drifts closely to a background current.Current affiliation (from Feb. 1, 1992): NCAR, P.O. Box 3000, Boulder, Colorado 80307-3000, U.S.A. 相似文献
76.
Ryuichiro Inoue Jiro Yoshida Yutaka Hiroe Kousei Komatsu Kiyoshi Kawasaki Ichiro Yasuda 《Journal of Oceanography》2003,59(2):211-224
The mixing processes in the Mixed Water Region (MWR) that lead to changes in the properties of North Pacific Intermediate
Water (NPIW) have been studied using observational data sets obtained in May–June 1998. Neutral surfaces, the equation of
water mass conversion rate on neutral surfaces and the equation of vertical velocity across neutral surfaces have been used
to distinguish dominant processes by assuming the horizontal scale to be the streamer scale (under 100 km). The possibility
of double diffusive convection is also discussed in relation to the density ratio. These results may be summarized as follows:
(1) the difference between the potential density surface and the neutral surface may rise to −0.04 kg/m3 around the source water of NPIW; (2) horizontal diffusion causes strong modifications of the source water of NPIW; (3) the
density range within which strong modification of the source water of NPIW occurs becomes dense from the northern part of
MWR near the Oyashio Front to the southern part near the Kuroshio Front, and to the eastern part. Our modeling of these processes
shows that cabbeling has effects on the density increment of the source water of NPIW in the northern and southern part of
MWR. Double diffusive convection has effects on the density increment of the source water of NPIW, mainly in the northern
part of MWR. The possible density increment due to cabbeling in these areas is estimated to be 0.01≈0.03 kg/m3. The possible density increment due to double diffusive convection is 0.01≈0.03 kg/m3. The total density increment due to cabbeling and double diffusive convection amounts to 0.06 kg/m3.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
77.
Numerical simulations using a full-nonlinear BIM (Boundary Integral Method) potential-theory wave model are carried out to study the internal velocity and acceleration fields of an solitary wave overturning on a reef with vertical face (submerged breakwater) and their relation to breaker type. The simulations make it clear that the jet size normalized by the incident wave height is uniquely governed by the crown height of the reef, while the jet shape is similar and independent of the size. Further, they reveal that the overall internal kinematics of overturning waves is clearly related to the jet size. As the jet size increases and the breaker type changes from spilling to plunging, the kinematics thus become increasingly different from those of steady waves. Water particles with the greatest velocities or accelerations within the wave converge towards the jet. After the breaking, both of the velocities and accelerations almost simultaneously reach extreme values near locations beneath the jet. Some of the extreme values are closely related to the breaker type and can be uniquely determined by substituting the breaker type index into the regression equations suggested here. 相似文献
78.
Hydrographic Structure and Transport of Intermediate Water in the Kuroshio Region off the Boso Peninsula, Japan 总被引:1,自引:1,他引:1
Kosei Komatsu Yutaka Hiroe Ichiro Yasuda Kiyoshi Kawasaki Terrence M. Joyce Frank Bahr 《Journal of Oceanography》2004,60(2):487-503
Hydrographic structure and transport of intermediate water were observed in the Kuroshio region south of Japan, focusing on
the 26.6–27.5σθ density in six cruises from May 1998 through September 2001. In the section off the Boso Peninsula where the Kuroshio exfoliates
eastward, the intermediate water was clearly clustered into three groups meridionally composed of the coastal water, the Kuroshio
water and the offshore water. Compared with the Kuroshio water characterized by warm, salty water transported by the Kuroshio,
the coastal and offshore waters significantly degenerated due to mixing with cold, fresh waters originated from the subarctic
region: the former was affected by alongshore spread of the coastal Oyashio and the latter by direct intrusion of the new
North Pacific Intermediate Water (NPIW) into the southern side of the Kuroshio current axis. Particularly the offshore water
showed higher apparent oxygen utilization (AOU) in layers deeper than 26.9σθ while it showed lower AOU in layers shallower than 26.9σθ, which indicated that colder, fresher and higher AOU water was distributed on the southeastern side of the Kuroshio in deeper
layers. In May 1998, the Oyashio-Kuroshio mixing ratio was estimated to be typically 2:8 for the offshore water on the assumption
of isopycnal mixing. Moreover, northeastward volume transport of the Kuroshio water was obtained from geostrophic velocity
fields adjusted to lowered acoustic Doppler current profiler (LADCP) data to yield 6.1 Sv at 26.6–26.9σθ and 11.8 Sv at 26.9–27.5 σθ.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
79.
80.
The bandpass eddy covariance method has been used to measure the turbulent flux of scalar quantities using a slow-responsescalar sensor. The method issimilar in principle to the traditional eddy correlation method but includes the estimation of high-frequency components of the flux on the basis of cospectral similarity in the atmospheric surface layer. In order to investigate the performance of the method, measurements of the water vapour flux over a forest with the bandpass eddy covariance method and the direct eddy correlation method were compared. The flux obtained by the bandpass eddy covariance method agreed with that by the eddy correlation method within ±20% for most cases, in spite of a rather slow sensor-response of the adopted hygrometer. This result supports its relevance to a long-term continuous operation, since a stable, low-maintenance,general-purpose sensor canbe utilized for scalar quantities. Oneweak point of the method isits difficulty in principle to measure the correct flux when the magnitude of the sensible heat flux is very small, because the method uses the sensible heat flux as a standard reference for the prediction of undetectable high-frequency components of the scalar flux. An advanced method is then presented to increase its robustness. In the new method, output signals from a slow-response sensor are corrected using empirical frequency-responsefunctions for the sensor,thereby extending the width of the bandpass frequency region where components of the flux are directly measured (not predicted). The advanced method produced correct fluxes for all cases including the cases of small sensible heat flux. The advanced bandpass eddy covariance method is thus appropriate for along-term measurement of the scalar fluxes. 相似文献