Effects of static stability and the C/N ratio on aggregation processes of oceanic particles     

Michimasa Kawakita  Masahiro Kajihara 《Journal of Oceanography》1990,46(1):1-8

The cumulative numbers of particles obtained from seven waters in the depth range of 0–100 m in coastal seas and in the North Pacific Ocean followed a hyperbolic distribution with two segments on log-log plots (132 sets of data). An alteration of the segment-slope in the fine size classes (1.59–10.08 μm in the coastal region, 1.59–6.35 μm in the open sea) was assumed to show a loss or a supply of fine particles due to aggregation or disaggregation. We studied relationships between segment slopes, static stabilities of water above the pycnocline which concern the dynamics of particles, and C/N ratios as an indicator of freshness of particles. A negative correlation between the segment-slope of particle size distribution and static stability was obtained, though the slope P of the regression line varied from 0.059 to 0.316. The average C/N ratio in the waters were in the range of 7.5 to 16.3. The slope P negatively correlated to the C/N ratio (r=−0.97). The present results suggested that aggregations of fine-sized particles in the sea are activated in the water with fresh organic matter and with high static stability.  相似文献   

Chemical modification of sea water by submarine volcanism at Nishinoshima-Shintô Island     

Yoshimasa Toyota  Satoru Kanamori  Michihiko Kodama  Masahiro Furukawa  Shiro Okabe 《Journal of Oceanography》1982,38(5):307-312

Sea water samples, still hot from volcanic emanations were taken in a bay of Nishinoshima-Shintô Island just after volcanic activity had ceased and were analysed for borate-B, fluoride-F and bromide-Br. The hot water is considered to be formed by the conservative mixing of volcanic emanations with sea water, and the emanations containedCl, B, F andBr in the ratio of 1∶1.84×10^?3∶0.474×10^?3∶6.47×10^?3 by weight. RatiosB/Cl andF/Cl can be used as effective measures of the contribution of volcanic emanations to sea water.  相似文献   

Settling velocity and porosity of large suspended particle     

Masahiro Kajihara 《Journal of Oceanography》1971,27(4):158-162

The settling velocity of large suspended particles which were formed in turbid water due to re-coagulation was measured in the laboratory, and the relation to the particle diameter which was taken as that of a sphere with the same volume, was obtained. This is, however, different from Stokes' law in regard to the relation to the particle diameter, though the Reynolds numbers are almost in the region of Stokes' law. This may be caused by the change of apparent density with the particle diameter. Stokes' law for a porous particle was applied to the settling velocity and the diameter found was compared with the real diameter to obtain an expression for the porosity. From the result, it is considered that the large suspended particles of “marine snow” have a porosity of above 90 %.  相似文献   

Intermediate Circulation in the Northwestern North Pacific Derived from Subsurface Floats     

Takanori Iwao  Masahiro Endoh  Nobuyuki Shikama  Toshiya Nakano 《Journal of Oceanography》2003,59(6):893-904

In order to examine the formation, distribution and synoptic scale circulation structure of North Pacific Intermediate Water (NPIW), 21 subsurface floats were deployed in the sea east of Japan. A Eulerian image of the intermediate layer (density range: 26.6–27.0σ_θ) circulation in the northwestern North Pacific was obtained by the combined analysis of the movements of the subsurface floats in the period from May 1998 to November 2002 and historical hydrographic observations. The intermediate flow field derived from the floats showed stronger flow speeds in general than that of geostrophic flow field calculated from historical hydrographic observations. In the intermediate layer, 8 Sv (1 Sv ≡ 10⁶ m³s⁻¹) Oyashio and Kuroshio waters are found flowing into the sea east of Japan. Three strong eastward flows are seen in the region from 150°E to 170°E, the first two flows are considered as the Subarctic Current and the Kuroshio Extension or the North Pacific Current. Both volume transports are estimated as 5.5 Sv. The third one flows along the Subarctic Boundary with a volume transport of 5 Sv. Water mass analysis indicates that the intermediate flow of the Subarctic Current consists of 4 Sv Oyashio water and 1.5 Sv Kuroshio water. The intermediate North Pacific Current consists of 2 Sv Oyashio water and 3.5 Sv Kuroshio water. The intermediate flow along the Subarctic Boundary contains 2 Sv Oyashio water and 3 Sv Kuroshio water. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

On “the upward transport of sediment by time-varying current”     

Masahiro Kajihara  Katsuhiko Matsunaga  Yoshiaki Maita 《Journal of Oceanography》1975,31(5):216-218

  相似文献   

On a damped eigen oscillation of vortex motion excited by wind stress over a ridge     

Masahiro Endoh 《Journal of Oceanography》1973,29(4):159-162

  相似文献   

II-2 On the starting and quasi-steady characteristics of wells turbine under oscillating flow condition     

Masahiro Inoue  Kenji Kaneko  Toshiaki Setoguchi  Katsumi Shimamoto 《Ocean Engineering》1985,12(6):563

  相似文献   

Application of data assimilation in portable operational forecasting systems—the DATools assimilation environment   总被引：1，自引：1，他引：1  

Ghada Y. El Serafy  Herman Gerritsen  Stef Hummel  Albrecht H. Weerts  Arthur E. Mynett  Masahiro Tanaka 《Ocean Dynamics》2007,57(4-5):485-499

  相似文献   

Geological causes and geomorphological precursors of the Tsaoling landslide triggered by the 1999 Chi-Chi earthquake, Taiwan   总被引：5，自引：0，他引：5  

Masahiro Chigira  Wen-Neng Wang  Takahiko Furuya  Toshitaka Kamai   《Engineering Geology》2003,68(3-4):259-273

The Tsaoling landslide, one of the largest landslide areas in Taiwan, has been affected by catastrophic events triggered by rain or earthquakes six times since 1862. These landslides, including that caused by the 1999 earthquake, have essentially not been reactivated old slides, but were sequential new ones that developed upslope, retrogressively. The landslide area is underlain by Pliocene sandstone and shale to form a dip slope with a bedding plane, dipping uniformly at 14°. The slip surface of the 1999 landslide was smooth and planar, parallel to the bedding plane with a slightly stepped profile; it formed within thinly alternated beds of fine sandstone and shale with ripple lamination or in a shale bed. The shale is weathered by slaking and probably by sulfuric acid, which is inferred to be one of the major causes of the intermittent retrogressive development of the landslides. The weathering was likely accelerated by the removal of overlying beds during earlier landslides in 1941 and 1942. The top margin of the 1999 landslide, in plan view, coincided with a V-shaped scarplet, which can be clearly recognized on aerial photographs taken before the landslide. This geomorphological feature indicates that this landslide had already moved slightly before its 1999 occurrence, providing precursory evidences.  相似文献   

Effects of merging histories on angular momentum distribution of dark matter haloes     

Masahiro Nagashima  & Naoteru Gouda 《Monthly notices of the Royal Astronomical Society》1998,301(3):849-860

The effects of merging histories of proto-objects on the angular momentum distributions of the present-time dark matter haloes are analysed. An analytical approach to the analysis of the angular momentum distributions assumes that the haloes are initially homogeneous ellipsoids and that the growth of the angular momentum of the haloes halts at their maximum expansion time. However, the maximum expansion time cannot be determined uniquely, because in the hierarchical clustering scenario each progenitor, or subunit, of the halo has its own maximum expansion time. Therefore the merging history of the halo may be important in estimating its angular momentum. Using the merger tree model by Rodrigues &38; Thomas, which takes into account the spatial correlations of the density fluctuations, we have investigated the effects of the merging histories on the angular momentum distributions of dark matter haloes. It was found that the merger effects, that is, the effects of the inhomogeneity of the maximum expansion times of the progenitors which finally merge together into a halo, do not strongly affect the final angular momentum distributions, so that the homogeneous ellipsoid approximation happens to be good for the estimation of the angular momentum distribution of dark matter haloes. This is because the effect of the different directions of the angular momenta of the progenitors cancels out the effect of the inhomogeneity of the maximum expansion times of the progenitors.   The contribution of the orbital angular momentum to the total angular momentum when two or more pre-existing haloes merge together was also investigated. It is shown that this contribution is more important than that of the angular momentum of diffuse accreting matter to the total angular momentum, especially when the mergers occur many times.  相似文献