Heat budget in the Japan Sea     

Naoki Hirose  Cheol-Ho Kim  Jong-Hwan Yoon 《Journal of Oceanography》1996,52(5):553-574

The long-term mean (31-year mean) surface heat fluxes over the Japan Sea are estimated by the bulk method using the most of the available vessel data with the resolution of 1^o×1^o. The long-term annual mean net heat flux is about –53 W m^–2 (negative sign means upward heat flux) with the annual range from 133 W m^–2 in May to –296 W m^–2 in December. The small gain of heat in the area near Vladivostok seems to indicate the existence of cold water flowing from the north. In that area in winter, the mean loss of heat attains about 200 W m^–2, and the Bowen's ratio is over the unity. The largest insolation occurs in May in the Japan Sea, and the upward latent heat flux becomes the largest in November in this area. The heat flux of Haney type is also calculated, and the result, shows that the constantQ ₁ has the remarkable seasonal and spatial variation, while the coefficientQ ₂ has relatively small variation throughout all seasons. Under the assumption of constant volume transport of 1.35×10⁶ m³s^–1 through the Tsugaru Strait, the long-term averages of the volume transport through the Tsushima and Soya Straits are estimated to be about 2.20 and 0.85×10⁶ m³s^–1 from the result of the mean surface heat flux, respectively.  相似文献   

Zonally asymmetric response of the Japan Sea to synoptic pressure forcing     

Daisuke Inazu  Naoki Hirose  Shoichi Kizu  Kimio Hanawa 《Journal of Oceanography》2006,62(6):909-916

We investigated the sea level response of the Japan Sea to changes in atmospheric pressure using barotropic shallow water models driven by idealized synoptic pressure forcing. The regional response lags behind the synoptic pressure forcing because the adjustment is slowly established by water exchange through narrow, shallow straits. The sea level response of the realistic Japan Sea to the idealized forcing varies with geographical location and shows zonally asymmetric variations in amplitude and phase. The simulated response is in good agreement with the observed response of sea level recorded at Japanese coastal tide gauges. The results of a simple one-dimensional model indicate that the zonally asymmetric pattern, with an eastward-propagating pressure system, is essentially caused by bottom friction in shallow straits. This asymmetry arises if the typical wavelength of the synoptic pressure system is slightly larger than the spatial scale of the Japan Sea.  相似文献   

Evidence of Microbial Activity in the Formation of Manganese Wads at the Asahidake Hot Spring in Hokkaido, Japan     

Naoki Mita  Hiroyuki Miura 《Resource Geology》2003,53(3):233-238

Abstract. Mt. Asahidake is an active volcano, with more than 90 active wells, in the Daisetsu volcanic group located in central Hokkaido, Japan. Wells along the Yukomanbetsu-sawa River showed high manganese concentrations and associated manganese deposits. These deposits consist of manganese oxides, and the concentration of iron is very low except for one sample collected from the upper reach of the river. Most of the wet samples showed basal diffraction characteristic of todorokite (9.6 Å). Cultivation tests showed that microorganisms were responsible for the oxidation of dissolved Mn²⁺ in the Asahidake hot spring. The dissolved Mn²⁺ concentration in the sterilized hot spring water was unchanged after four days, whereas the Mn²⁺ concentration in the sterilized hot spring water with a small amount of fresh manganese wad was decreased to zero after three days, and manganese oxide formed. This result implies that the activity of microorganism oxidizes dissolved Mn²⁺ and forms manganese oxide at the Asahidake manganese deposits. In addition to Komanoyu hot spring and Yunotaki Falls, this is the third report of microbial activity forming considerable deposits of manganese oxides in hot spring waters.  相似文献   

The use of RFID in soil‐erosion research          下载免费PDF全文

Anthony John Parsons  Yuichi Onda  Takehiro Noguchi  Jeremy Patin  James Cooper  John Wainwright  Naoki Sakai 《地球表面变化过程与地形》2014,39(12):1693-1696

In this paper, we examine the use of radio frequency identification (RFID) tags for studying soil erosion. Surrogate soil particles were created by coating RFID tags with silicone clay and bronze powder to give them an overall density similar to that of quartz particles. The particles were between 2.5 mm and 4.0 mm in diameter and had specific weights of 2.5 to 3.0. These tagged particles were deployed on two plots: first, in a proof‐of‐concept laboratory study and secondly in a field study, the latter involving repeated surveys after rainfall events. Seven surveys under natural rainfall over four months yielded recovery rates averaged 56%. RFIDs are shown to provide useful insights into the movement of individual soil particles during erosion processes. As RFID technology advances, further miniaturization is likely to occur enabling the movement of a greater range of soil particles to be studied, and we may anticipate improvements to the signal detection so that recovery does not rely wholly on visual identification. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Green’s function approach for calibrating tides in a circulation model for the East Asian marginal seas     

Jae-Hong Moon  Naoki Hirose  Akihiko Morimoto 《Journal of Oceanography》2012,68(2):345-354

A simple effective method of inverse estimation provided by model Green’s functions is examined to calibrate tides in a regional circulation model for the East Asian marginal seas. The Green’s function optimization derived by perturbing the model parameters significantly improves the estimate relative to observation as compared with baseline integration. Among the optimized model parameters, the largest effects on cost function reduction come first from the harmonic constant of M₂ along the open boundaries with the optimized values of 89.7 ± 0.8% for amplitude, and second from the bottom friction with the optimized value of (3.06 ± 0.08) × 10⁻³.  相似文献   

Relativistic corrections to the multiple scattering effect on the Sunyaev–Zel'dovich effect in the isotropic approximation     

Naoki Itoh  Youhei Kawana  Satoshi Nozawa  Yasuharu Kohyama 《Monthly notices of the Royal Astronomical Society》2001,327(2):567-576

We extend the formalism for the calculation of the relativistic corrections to the Sunyaev–Zel'dovich effect for clusters of galaxies and include the multiple scattering effects in the isotropic approximation. We present the results of the calculations by the Fokker–Planck expansion method as well as by the direct numerical integration of the collision term of the Boltzmann equation. The multiple scattering contribution is found to be very small compared with the single scattering contribution. For high-temperature galaxy clusters of     the ratio of both the contributions is −0.2 per cent in the Wien region. In the Rayleigh–Jeans region the ratio is −0.03 per cent. Therefore the multiple scattering contribution is safely neglected for the observed galaxy clusters.  相似文献   

Distribution of the pre-solar component in Allende and other carbonaceous chondrites     

Robert N. Clayton  Naoki Onuma  Lawrence Grossman  Toshiko K. Mayeda 《Earth and Planetary Science Letters》1977,34(2):209-224

  相似文献   

Relationship between groundwater flow estimated by soil temperature and slope failures caused by heavy rainfall, Shikoku Island, southwestern Japan   总被引：2，自引：0，他引：2  

Gen Furuya  Akira Suemine  Kyoji Sassa  Takeshi Komatsubara  Naoki Watanabe  Hideaki Marui 《Engineering Geology》2006,85(3-4):332-346

Most of the slope failure disasters in a humid area such as that of Japan are caused by heavy rain. However, even for the case of heavy rainfall that occurs once in every 10 years, total area of slope failures seldom exceeds 10% of a watershed. From this background, we focused on the vein-like groundwater flows that increase pore-water pressure, and clarified the relationship between distributions of slope failures and groundwater veins. In this study, a 1-m-depth ground temperature survey and water-chemistry analyses at springs and boreholes were conducted in Zentoku area of Shikoku Island, southwestern Japan, to grasp the distribution of groundwater veins and their sources. Subsequently, slope-stability was analyzed to investigate the relationship between groundwater veins and slope failures at study sites. These results lead to the following conclusions: The slope failures appear to concentrate around shallow groundwater veins and groundwater veins rising from deep layers. This means that slope failures caused by these groundwater veins in addition to rainfall. Two types of groundwater originate in the deep layers: one has short storage time as indicated by the fact that dissolved substances are low; the other is stored for a lengthy period as noted by a high concentration of dissolved substances. By combining the results of stability analyses and distribution of groundwater veins, it is suggested that prediction of zones with high potential for slope failure can be more accurate.  相似文献   

Hierarchy of tectonic control on stratigraphic signatures: Base-level changes during the Early Permian in the Paraná Basin, southernmost Brazil     

Michael Holz  Juliano Küchle  Ruy Paulo Philipp  Alan Patrick Bischoff  Naoki Arima 《Journal of South American Earth Sciences》2006,22(3-4):185

The Lower Permian sedimentary succession of the Paraná Basin in southernmost Brazil has an overall transgressive sedimentation regime, recorded by a clear retrogradation of the facies belt. However, important depositional strike-orientated variations and regional inversions occur in the sedimentation regime along the paleo-shoreline (i.e., along-strike) of the basin. At the regional scale, a huge source area was uplifted by the end of the Artinskian in the north and caused regression; the southern part of the study area increasingly was transgressed by the epicontinental sea (= regional inversion). This important tectonic overprint on the stratigraphic signature of the basin’s infill has a tectonic origin. The variable sedimentation regime along the paleo-shoreline is controlled by the structural framework of the basement, which is formed by several crustal blocks with different responses to tectonic strain induced by terrain accretion on the occidental margin of Gondwana during the Permian. Stratigraphic data indicate that during the Early Permian, there were at least two differential subsidence and uplift events, one by the end of the Sakmarian–Artinskian and another during the Late Artinskian–Kungurian.  相似文献   

Anomalously large seismic amplifications in the seafloor area off the Kii peninsula     

Takeshi Nakamura  Masaru Nakano  Naoki Hayashimoto  Narumi Takahashi  Hiroshi Takenaka  Taro Okamoto  Eiichiro Araki  Yoshiyuki Kaneda 《Marine Geophysical Researches》2014,35(3):255-270

Seismic wave amplifications were investigated using strong-motion data obtained from the ground’s surface (K-net) on the Kii peninsula (southwestern Japan) and from the network of twenty seismic stations on the seafloor (DONET) located off the peninsula near the Nankai trough. Observed seismograms show that seismic signals at DONET stations are significantly larger than those at K-net stations, independent of epicentral distances. In order to investigate the cause of such amplifications, seismic wavefields for local events were simulated using the finite-difference method, in which a realistic 3D velocity structure in and around the peninsula was incorporated. Our simulation results demonstrate that seismic waves are significantly amplified at DONET stations in relation to the presence of underlying low-velocity sediment layers with a total thickness of up to 10 km. Our simulations also show considerable variations in the degree of amplification among DONET stations, which is attributed to differences in the thickness of the sediment layers. The degree of amplification is relatively low at stations above thin sediment layers near the trough axis, but seismic signals are much more amplified at stations closer to the Kii peninsula, where sediment layers are thicker than those at the trough axis. Simulation results are consistent with observations. This study, based on seafloor observations and simulations, indicates that because seismic signals are amplified due to the ocean-specific structures, the magnitude of earthquakes would be overestimated if procedures applied to data observed at land stations are used without corrections.  相似文献