A physically based distributed subsurface–surface flow dynamics model for forested mountainous catchments     

Deogratias M. M. Mulungu  Yutaka Ichikawa  Michiharu Shiiba 《水文研究》2005,19(20):3999-4022

This study was designed to develop a physically based hydrological model to describe the hydrological processes within forested mountainous river basins. The model describes the relationships between hydrological fluxes and catchment characteristics that are influenced by topography and land cover. Hydrological processes representative of temperate basins in steep terrain that are incorporated in the model include intercepted rainfall, evaporation, transpiration, infiltration into macropores, partitioning between preferential flow and soil matrix flow, percolation, capillary rise, surface flow (saturation‐excess and return flow), subsurface flow (preferential subsurface flow and baseflow) and spatial water‐table dynamics. The soil–vegetation–atmosphere transfer scheme used was the single‐layer Penman–Monteith model, although a two‐layer model was also provided. The catchment characteristics include topography (elevation, topographic indices), slope and contributing area, where a digital elevation model provided flow direction on the steepest gradient flow path. The hydrological fluxes and catchment characteristics are modelled based on the variable source‐area concept, which defines the dynamics of the watershed response. Flow generated on land for each sub‐basin is routed to the river channel by a kinematic wave model. In the river channel, the combined flows from sub‐basins are routed by the Muskingum–Cunge model to the river outlet; these comprise inputs to the river downstream. The model was applied to the Hikimi river basin in Japan. Spatial decadal values of the normalized difference vegetation index and leaf area index were used for the yearly simulations. Results were satisfactory, as indicated by model efficiency criteria, and analysis showed that the rainfall input is not representative of the orographic lifting induced rainfall in the mountainous Hikimi river basin. Also, a simple representation of the effects of preferential flow within the soil matrix flow has a slight significance for soil moisture status, but is insignificant for river flow estimations. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Near-Infrared Colors of the Binary Kuiper Belt Object 1998 WW 31     

Takato  Naruhisa  Fuse  Tetsuharu  Gaessler  Wolfgang  Goto  Miwa  Kanzawa  Tomio  Kobayashi  Naoto  Minowa  Yosuke  Oya  Shin  Pyo  Tae-Soo  Saint-Jacque  D.  Takami  Hideki  Terada  Hiroshi  Hayano  Yutaka  Iye  Masanori  Kamata  Yukiko  Tokunaga  A. T. 《Earth, Moon, and Planets》2003,92(1-4):183-191

We have measured near-infrared colorsof the binary Kuiper Belt object (KBO)1998 WW₃₁ using the Subaru Telescope withadaptive optics. The satellite was detectednear its perigee and apogee(0.18“ and 1.2” apart from the primary).The primary and the satellite have similar H–Kcolors, while the satellite is redder thanthe primary in J–H. Combined with the Rband magnitude previously published byVeillet et al., 2002, the color of the primaryis consistent with that of optically red KBOs. Thesatellite's R-, J-, H-colors suggest thepresence of ～1 μm absorption band dueto rock-forming minerals. If the surface of thesatellite is mainly composed by olivine, thesatellite's albedo is higher value than the canonicallyassumed value of 4%.  相似文献   

Recipe for Predicting Strong Ground Motion from Crustal Earthquake Scenarios   总被引：3，自引：0，他引：3  

Kojiro Irikura  Hiroe Miyake 《Pure and Applied Geophysics》2011,168(1-2):85-104

We developed a recipe for predicting strong ground motions based on a characterization of the source model for future crustal earthquakes. From recent developments of waveform inversion of strong motion data used to estimate the rupture process, we have inferred that strong ground motion is primarily related to the slip heterogeneity inside the source rather than average slip in the entire rupture area. Asperities are characterized as regions that have large slip relative to the average slip on the rupture area. The asperity areas, as well as the total rupture area, scale with seismic moment. We determined that the areas of strong motion generation approximately coincide with the asperity areas. Based on the scaling relationships, the deductive source model for the prediction of strong ground motions is characterized by three kinds of parameters: outer, inner, and extra fault parameters. The outer fault parameters are defined as entire rupture area and total seismic moment. The inner fault parameters are defined as slip heterogeneity inside the source, area of asperities, and stress drop on each asperity based on the multiple-asperity model. The pattern of rupture nucleation and termination are the extra fault parameters that are related to geomorphology of active faults. We have examined the validity of the earthquake sources constructed by our recipe by comparing simulated and observed ground motions from recent inland crustal earthquakes, such as the 1995 Kobe and 2005 Fukuoka earthquakes.  相似文献   

Development of the core‐suspended isolation system     

Yutaka Nakamura  Masaaki Saruta  Akira Wada  Toru Takeuchi  Shigeru Hikone  Teiichi Takahashi 《地震工程与结构动力学》2011,40(4):429-447

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Strong ground motion simulation of the 2003 Bam, Iran, earthquake using the empirical Green’s function method     

Hossein Sadeghi  Hiroe Miyake  Ali Riahi 《Journal of Seismology》2013,17(2):297-312

The 2003 Bam, Iran, earthquake caused catastrophic damage to the city of Bam and neighboring villages. Given its magnitude (M _w ) of 6.5, the damage was remarkably large. Large-amplitude ground motions were recorded at the Bam accelerograph station in the center of Bam city by the Building and Housing Research Center (BHRC) of Iran. We simulated the Bam earthquake acceleration records at three BHRC strong-motion stations—Bam, Abaraq, and Mohammad-Abad—by the empirical Green’s function method. Three aftershocks were used as empirical Green’s functions. The frequency range of the empirical Green’s function simulations was 0.5–10 Hz. The size of the strong motion generation area of the mainshock was estimated to be 11 km in length by 7 km in width. To estimate the parameters of the strong motion generation area, we used 1D and 2D velocity structures across the fault and a combined source model. The empirical Green’s function method using a combination of aftershocks produced a source model that reproduced ground motions with the best fit to the observed waveforms. This may be attributed to the existence of two distinct rupture mechanisms in the strong motion generation area. We found that the rupture starting point for which the simulated waveforms best fit the observed ones was near the center of the strong motion generation area, which reproduced near-source ground motions in a broadband frequency range. The estimated strong motion generation area could explain the observed damaging ground motion at the Bam station. This suggests that estimating the source characteristics of the Bam earthquake is very important in understanding the causes of the earthquake damage.  相似文献   

Modeling Marine Stratocumulus with a Detailed Microphysical Scheme   总被引：1，自引：0，他引：1  

ZHAO Chunsheng  Yutaka ISHIZAKA 《大气科学进展》2004,21(1):61-74

A one-dimensional 3rd-order turbulence closure model with size-resolved microphysics and radiative transfer has been developed for investigating aerosol and cloud interactions of the stratocumulus-topped marine boundary layer. A new method is presented for coupling between the dynamical model and the mierophysical model. This scheme allows the liquid water related correlations to be directly calculated rather than parameterized. On 21 April 2001, a marine stratocumulus was observed by the Caesar aircraft over the west Pacific Rim south of Japan during the 2001 APEX/ACE-Asia field measurements. This cloud is simulated by the model we present here. The model results show that the general features of the stratocumulus-topped marine boundary layer predicted by the model are in agreement with the measurements. A new onboard cloud condensation nuclei (CCN) counter provides not only total CCN number concentration (as the traditional CCN counters do at a certain supersaturation) but also the CCN size distribution information. Using these CCN data, model responses to different CCN initial concentrations are examined. The model results are consistent with both observations and expectations.The numerical results show that the cloud microphysieal properties are changed fundamentally by different initial CCN concentrations but the cloud liquid water content does not differ significantly. Different initial CCN loadings have large impacts on the evolution of cloud microstructure and radiation transfer while they have a modest effect on thermodynamics. Increased CCN concentration leads to significant decrease of cloud effective radius.  相似文献   

Baroclinic circulation and its high frequency variability in Otsuchi Bay on the Sanriku ria coast,Japan     

Kiyoshi Tanaka  Kousei Komatsu  Sachihiko Itoh  Daigo Yanagimoto  Miho Ishizu  Hiroyasu Hasumi  Takashi T. Sakamoto  Shogo Urakawa  Yutaka Michida 《Journal of Oceanography》2017,73(1):25-38

Hydrographic observations were made in Otsuchi Bay on the Sanriku ria coast, Japan, to provide clear images of the baroclinic circulation extending over the bay together with the associated intrusion of lower-layer water (bottom water) from outside the bay. In summer, a prominent baroclinic circulation with flow speeds \({>} 0.1\ \text{ m }\ \text{ s }^{-1} \) extends over the greater part of the bay. A main pycnocline (thermocline), which separates the upper and lower layers, is located at a depth of 15–40 m in and around the bay. The direction of the lower-layer flow (inflow into and outflow from the bay) is opposite to that of the upper-layer flow, which are baroclinically coupled to each other. Moreover, with regard to the lower-layer flow, the inflow tends to occur mainly through the northwestern part of the bay mouth, whereas the outflow tends to occur mainly through the southeastern part. The inflow and outflow alternate on time scales of several to a few tens of hours, and the flow directions are sometimes related to the tidal ones, although the relationship is not applied persistently. In winter, the baroclinic circulation is considerably weaker than in summer, because the stratification breaks down.  相似文献   

Sudden strong current generated by an eddy in the eastern part of Wakasa Bay,Japan     

Atsushi Kaneda  Kouta Ayukawa  Naoki Hirose  Jun Tsuzuki  Yutaka Kumaki  Tomoharu Senjyu  Yosuke Igeta  Tatsuro Watanabe 《Journal of Oceanography》2017,73(2):181-192

A sudden strong coastal current called a “kyucho” occurred in August 2013 in the eastern coastal waters of Wakasa Bay, Japan. This study examined its characteristics based on both observational data collected by intensive field investigations and the simulation results of a numerical model. The field investigations comprised moored buoy observations near the coast and voyages by a research vessels and fishing boats. The mooring observations indicated that a current speed exceeding 50 cm s^?1 occurred abruptly near the eastern coast of the bay, in association with a synchronous change in the current direction. Data collected by acoustic Doppler current profilers (ACDPs) mounted on the vessels showed that a clockwise eddy existed in the bay and that the current on the east side of the eddy generated the kyucho near the coast. Based on the results of the numerical model and the analysis of the ADCP data, it was considered that the clockwise eddy was generated by a strong current at the tip of the Tango Peninsula, in the western part of the bay. As the eddy propagated from west to east across the bay, it induced the kyucho in the coastal waters in the east of the bay.  相似文献   

Mixing process on the northeast coast of Hokkaido in summer     

Miho Ishizu  Yujiro Kitade  Yutaka Michida 《Journal of Oceanography》2013,69(1):1-13

Direct measurements using a free-falling micro-profiler were conducted on the northeast coast of Hokkaido in the summer of 2007 to clarify the mixing process in the Soya Warm Current (SWC) region in terms of microstructure. The distribution of the Turner angle (Tu) showed that these regions have a high potential for double diffusive convection, but direct measurements of the turbulent dissipation rate (ε) and dissipation of temperature variance ( $ \chi_{T} $ ) did not necessarily correspond to each other in the SWC region, especially in the offshore front of SWC and farther offshore. The mixing efficiency indicated that, even though the Turner angle (Tu) indicated a high potential for double diffusive convection, turbulent mixing was the main contributor to the mixing process in this region, and double-diffusive convection only contributed partially and sparsely, especially in the boundary off SWC water. The bottom mixed layer (BML) is known to thicken off the SWC. The vertical diffusivity coefficient was enhanced near the bottom (10^?4–10^?3 m² s^?1) off the SWC, and these results support that turbulence near the bottom off the SWC contributed to the thickening of the BML.  相似文献   

Preliminary results of the Japan-Taiwan joint survey on combining ocean radar data in the Kuroshio upstream region     

Kaoru Ichikawa  Wen Chang Yang  Akihiko Morimoto  Yutaka Yoshikawa  Shigeo Sugitani  Wen-Shan Chiang  Jian-Wu Lai  En Yu Liang  Cho-Teng Liu  Chang-Wei Lee  Kei Yufu  Moeto Kyushima  Satoshi Fujii  Tomoharu Senju  Yoshihiko Ide 《Ocean Science Journal》2013,48(1):141-148

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