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121.
Anomalous sea level, anomalous observed dynamic height (0/400 db) and anomalous model dynamic height are examined at the locations
of 13 island sea level stations in the tropical Pacific for each bimonth of the four year period 1979 to 1982. Starting in
1981, the anomalous dynamic height data show off-equatorial Rossby waves propagated toward the W boundary of the Pacific basin.
At the W boundary, the model Rossby wave activity was found to have excited coastally trapped Kelvin-Munk waves which transmitted
the anomalous dynamic height equatorward. At the equator, coastally trapped wave activity excited eastward propagating equatorial
Kelvin waves, yielding a pair of anomalous peaks in dynamic height variability in the E equatorial Pacific associated with
the 1982–1983 ENSO event. The evolution of the peaks in dynamic height associated with the Rossby and Kelvin wave activity
reflects the redistribution of observed upper-ocean heat content in the W tropical Pacific, providing a qualitative hindcast
for the 1982–1983 ENSO event.
In consequence of these results, and the results of a related study (Inoue et al. 1985), the redistribution of both observed
and model heat content, as evidenced in dynamic height in the W Pacific during the 23-year period 1964–1985, is examined for
its ability to hindcast and forecast ENSO events in this period. Complex EOF analysis is applied to the Onset Phase of ENSO
events occurring in 1968–69, 1972–73, 1976–77, and 1982–83; it is used to determine the characteristic redistribution of heat
content (dynamic height) prior to the Mature Phase of ENSO events. This analysis found both model and observed dynamic height
in the N hemisphere to be characterized by wind-driven, westward propagating, baroclinic Rossby wave activity, having a remarkably
stable period of 3 years over the 23-year period. The complex time series associated with these first spatial eigen-functions
are used to construct observed and model hindcast indices that yield high values one year prior to the Mature Phase of ENSO
events of the period. These indices achieve these values due to the incidence upon the Philippine coast in fall/winter of
a positive anomaly in dynamic height propagating from the east at nondispersive Rossby long wave speeds. 相似文献
122.
Tomoko Kyuka Satomi Yamaguchi Yusuke Inoue Kattia Rubi Arnez Ferrel Hideto Kon Yasuyuki Shimizu 《地球表面变化过程与地形》2021,46(7):1225-1237
Previous studies have demonstrated that riparian vegetation leads to channel transformation from a multi-bar to a single-thread channel planform. However, it still remains unclear how the presence of pioneer and mature vegetation affects the morphodynamics of single-thread meandering rivers. In this study, we therefore investigated the effects of vegetation strength on the morphodynamic evolution of an experimental meandering channel. Three physical laboratory experiments were conducted using alfalfa sprouts in different life stages – no vegetation, immature vegetation, and mature vegetation – to simulate different floodplain vegetation strengths. Our results demonstrate that vegetation plays a key role in mediating bank erosion and point-bar accretion, and that this is reflected in both the evolution of the channel bed as well as the sediment flux. The presence of mature vegetation maintained a deep, single-thread channel by reducing bank erosion, thereby limiting both channel widening and sediment storage capacity. Conversely, an unvegetated floodplain led to channel widening and high sediment storage capacity. Channel evolution in the unvegetated scenario showed that the active sediment supply from outer bank erosion led to slightly delayed point-bar accretion on the inner banks due to helical flow, deflecting the surface flow toward the outer banks and causing further erosion. In contrast, in the immature vegetation scenario, the outer banks were also initially eroded, but point-bar accretion did not clearly progress. This led to a greater width-to-depth ratio, resulting in a transition from a single- to a multi-thread channel with minor flow paths on the floodplain. The experimental results suggest that the eco-morphodynamic effects of young (low-strength) and mature (high-strength) vegetation are different. Notably, low-strength, early-stage vegetation increases channel complexity by accelerating both channel widening and branching, and therefore might promote the coexistence of multi-bars and pioneer vegetation. 相似文献
123.
124.
125.
Mutsuo Inoue Yusuke Nakano Yoko Kiyomoto Hisaki Kofuji Yasunori Hamajima Masayoshi Yamamoto 《Journal of Oceanography》2010,66(3):425-428
A total of 21 surface water samples were collected on the east side of the East China Sea (ECS) (3 sites) and at the Tsushima
Strait (1 site), and 226Ra and 228Ra activities were measured using low-background γ-spectrometry. The 228Ra/226Ra ratios among the samples exhibited notable seasonal variation (228Ra/226Ra = 0.2–2.6) accompanying changes of salinity (31.7–34.7). Seasonal water circulation within the ECS is hypothesized to cause
the change by altering the mixing ratio of 228Ra-rich continental shelf water and 228Ra-poor Kuroshio water. 相似文献
126.
A new type of rock drill, which has compact size and a simple mechanism and which can be automatically operated in water, was developed. The drill can obtain 75 cm of rock core from a rocky bottom covered by thin sediments at a maximum depth of 300 m.The drill was operated under a current of 1.5 knots in Sagami Bay south of Tokyo and obtained a 40-cm core of volcanic conglomerate of Miocene age from the slope of a small bank at a depth of 130 m. During the operation the vessel was not anchored. 相似文献
127.
In order to investigate ways of reducing vibrations of building structures subjected to excitation acting on intermediate storey, active vibration controls are conducted with active control devices installed on different floors of the structure, and the effective location of control devices is also investigated. In this paper, we propose a new ‘Discrete‐Optimizing Control Method’ for vibration control. The control forces are determined analytically which makes the ‘discrete‐index function’ minimum. Through numerical simulation, the Discrete‐Optimizing Control Method is proved to be an effective control method. The response reduction effects are best when the control devices are concentrated on the adjacent three floors of the vibration source. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
128.
Yoshio Inoue Yoshiyuki Kiyono Hidetoshi Asai Yukihito Ochiai Jiaguo Qi Albert Olioso Tatsuhiko Shiraiwa Takeshi Horie Kazuki Saito Linkham Dounagsavanh 《International Journal of Applied Earth Observation and Geoinformation》2010
In the tropical mountains of Southeast Asia, slash-and-burn (S/B) agriculture is a widely practiced and important food production system. The ecosystem carbon stock in this land-use is linked not only to the carbon exchange with the atmosphere but also with food and resource security. The objective of this study was to provide quantitative information on the land-use and ecosystem carbon stock in the region as well as to infer the impacts of alternative land-use and ecosystem management scenarios on the carbon sequestration potential at a regional scale. The study area was selected in a typical slash-and-burn region in the northern part of Laos. The chrono-sequential changes of land-use such as the relative areas of community age and cropping (C) + fallow (F) patterns were derived from the analysis of time-series satellite images. The chrono-sequential analysis showed that a consistent increase of S/B area during the past three decades and a rapid increase after 1990. Approximately 37% of the whole area was with the community age of 1–5 years, whereas 10% for 6–10 years in 2004. The ecosystem carbon stock at a regional scale was estimated by synthesizing the land-use patterns and semi-empirical carbon stock model derived from in situ measurements where the community age was used as a clue to the linkage. The ecosystem carbon stock in the region was strongly affected by the land-use patterns; the temporal average of carbon stock in 1C + 10F cycles, for example, was greater by 33 MgC ha−1 compared to that in 1C + 2F land-use pattern. The amount of carbon lost from the regional ecosystems during 1990–2004 periods was estimated to be 42 MgC ha−1. The study approach proved to be useful especially in such regions with low data-availability and accessibility. This study revealed the dynamic change of land-use and ecosystem carbon stock in the tropical mountain of Laos as affected by land-use. Results suggest the significant potential of carbon sequestration through changing land-use and ecosystem management scenarios. These quantitative estimates would be useful to better understand and manage the land-use and ecosystem carbon stock towards higher sustainability and food security in similar ecosystems. 相似文献
129.
A numerical procedure for a dynamic non-linear finite element analysis is proposed here to analyse three-dimensional reinforced concrete shear wall structures subjected to earthquake motions. A shear wall is modelled as a quasi-three dimensional structure which is composed of plane elements considering the in-plane stiffness of orthogonal flange panels. The proposed constitutive model is based on the non-linearity of reinforcement and concrete in which the tension stiffening in tension and the degradation of stiffness and strength in compression of concrete after cracking are considered. The acceleration-pulse method, which is a kind of explicit analytical procedure, is employed to solve the non-linear dynamic equations, where the dynamic equation can be solved without stiffness matrix and so the iterative procedure is not necessary for descending portion of stress–strain relationship caused by cracking and softening after compressive strength in concrete. The damping effect is considered by assuming equivalent viscous damping which can give good cyclic behaviours of inertia force vs. displacement relationships. This analytical method was applied to a test specimen of a reinforced concrete shear wall with a H-shaped section which was vibrated up to failure by using a large-scale shaking table with high -performance in Japan. The test was performed as one of the dynamic model tests for evaluation of seismic behaviour of nuclear reactor buildings. The calculations were performed sequentially from the elastic range to failure. The comparison with the test results shows that this approach has good accuracy. © 1997 by John Wiley & Sons Ltd 相似文献
130.
Jun Inoue Masayuki Kawashima Kay I. Ohshima Yasushi Fujiyoshi Ken-ichi Maruyama 《Journal of Oceanography》2000,56(5):507-515
Horizontal wind fields over Funka Bay during cold air outbreaks were simulated using a 3-D meso-scale atmospheric model. The simulated wind fields over the bay have a positive curl in the north and a negative curl in the south. These wind fields were used to simulate the current in Funka Bay using a barotropic ocean model. The simulated current pattern was composed of two vortices—one with anti-clockwise vorticity in the north and the other with clockwise vorticity in the south—and was in the opposite direction to that simulated by the uniform wind fields. This is because the wind stress curl effect on the vorticity production in Funka Bay opposes and overwhelms the bathymetry torque effect during cold air outbreaks. These results show that the non-uniformity of the wind fields caused by the land topography around a shallow lake or bay cannot be neglected in simulating its currents. 相似文献