Thematic Issue: Rare Earth Resources: Are They Sufficient or Deficient?     

Yasushi Watanabe 《Resource Geology》2008,58(4):335-336

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Robustness,uncertainties, and emergent constraints in the radiative responses of stratocumulus cloud regimes to future warming   总被引：1，自引：0，他引：1  

Yoko Tsushima  Mark A. Ringer  Tsuyoshi Koshiro  Hideaki Kawai  Romain Roehrig  Jason Cole  Masahiro Watanabe  Tokuta Yokohata  Alejandro Bodas-Salcedo  Keith D. Williams  Mark J. Webb 《Climate Dynamics》2016,46(9-10):3025-3039

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Effects of mass sedimentation events after the 2011 off the Pacific coast of Tohoku Earthquake on benthic prokaryotes and meiofauna inhabiting the upper bathyal sediments     

Hidetaka Nomaki  Tomohiro Mochizuki  Tomo Kitahashi  Takuro Nunoura  Kazuno Arai  Takashi Toyofuku  Gengo Tanaka  Shuichi Shigeno  Eiji Tasumi  Katsunori Fujikura  Shuichi Watanabe 《Journal of Oceanography》2016,72(1):113-128

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Lithium and strontium isotopic systematics in playas in Nevada,USA: constraints on the origin of lithium   总被引：1，自引：0，他引：1  

Daisuke Araoka  Hodaka Kawahata  Tetsuichi Takagi  Yasushi Watanabe  Koshi Nishimura  Yoshiro Nishio 《Mineralium Deposita》2014,49(3):371-379

Lithium-rich brine in playas is a major raw material for lithium production. Recently, lithium isotopic ratios (δ⁷Li) have been identified as a tool for investigating water–rock interactions. Thus, to constrain the origin of lithium in playas by the use of its isotopes, we conducted leaching experiments on various lacustrine sediment and evaporite deposit samples collected from playas in Nevada, USA. We determined lithium and strontium isotopic ratios and contents and trace element contents of the leachate, estimated the initial δ⁷Li values in the water flowing into the playas, and examined the origin of lithium in playas by comparison with δ⁷Li values of the possible sources. In samples from the playas, δ⁷Li values show some variation, reflecting differences both in isotopic fractionation during mineral formation and in initial δ⁷Li value in water flowing into each playa. However, all δ⁷Li values in this study are much lower than those in river water and groundwater samples from around the world, but they are close to those of volcanic rocks. Considering the temperature dependence of lithium isotopic fractionation between solid and fluid, these results indicate that the lithium concentrated in playas in Nevada was supplied mainly through high-temperature water–rock interaction associated with local hydrothermal activity and not directly by low-temperature weathering of surface materials. This study, which is the first to report lithium isotopic compositions in playas, demonstrates that δ⁷Li may be a useful tracer for determining the origin of lithium and evaluating its accumulation processes in playas.  相似文献   

Grey model for prediction of pore pressure change     

Mebruk Mohammed  Kunio Watanabe  Shinji Takeuchi 《Environmental Earth Sciences》2010,60(7):1523-1534

Prediction of pore pressure change is an effective tool to properly monitor changes of groundwater flow caused by any construction work in fractured rock mass. Due to the complexity of hydrogeologic conditions in fractured rock and the scale of interest of the study domain, prediction of pore pressure changes by numerical models has not been precise enough to meet monitoring requirements. Considering these problems, a Grey model that combines the finite element method (FEM) and the artificial neural network (ANN) was developed for more precise prediction of pore pressure changes. In this model, several patterns of pore pressure changes were calculated by FEM for a simplified hydrogeologic conceptual model at a scale smaller than a representative elementary volume. The ANN model was then constructed to predict the actual pore pressure change using these FEM results as inputs. This modeling approach was adopted to predict the pore pressure changes caused by the construction of shafts of Mizunami Underground Research Laboratory (MIU), Japan. From the results obtained for MIU, it can be concluded that the proposed Grey model is a powerful tool for monitoring of pore pressure changes.  相似文献   

Application of underwater optical data to estimation of primary productivity     

Makio C. Honda  Kosei Sasaoka  Hajime Kawakami  Kazuhiko Matsumoto  Shuichi Watanabe  Tommy Dickey 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(12):2281-2292

We conducted time-series observations of optical fields near the base of the euphotic zone (approximately 40 m) using moored automatic optical sensors at a time-series station in the Western Pacific Subarctic Gyre from March 2005 to July 2006 (with some gaps). We used the ratio of photosynthetically available radiation at the surface (surface PAR) to in situ quantum irradiance (in situ QI) at about 40 m as an index of opacity (surface PAR/in situ QI), which began to increase in the middle of April and peaked between the end of June and the middle of July 2005. This ratio then decreased toward winter. The ratio increased again beginning in January 2006, and large peaks were observed in June and July 2006. As an index of chlorophyll abundance we used the ratio of spectral irradiance at wavelengths of 555 and 443 nm (Ed₅₅₅/Ed₄₄₃) at about 40 m; seasonal variability of this ratio synchronized well with the attenuation coefficient “k” estimated with surface PAR, in situ QI, and BLOOMS depth. We estimated primary productivity (PP) using Ed₅₅₅/Ed₄₄₃ and an empirical equation based on a previous model but improved on the basis of shipboard observations. Estimated PP agreed well with observed PP. Seasonal variability of estimated PP was synchronized with that of organic carbon flux observed by sediment traps from approximately 150, 540, 1000, and 5000 m. This study demonstrates that time-series observations of in situ optical fields could contribute to the estimation of primary productivity and the study of the biological pump in the ocean.  相似文献   

Spin Temperature of Ammonia Determined from NH2 in Comet C/2001 A2 (LINEAR)     

Kawakita  Hideyo  Watanabe  Jun-Ichi  FUSE  Tetsuharu  Furusho  Reiko  Abe  Shinsuke 《Earth, Moon, and Planets》2002,90(1-4):371-379

The ortho-to-para ratio (OPR) of a cometary molecule is one of primordial character in comets. The OPR which is characterized by a spin temperature, is thought to reflect the formation conditions of the molecule. In this paper we show the high-dispersion spectrum of cometary NH₂ in Comet C/2001 A2 (LINEAR), from which the OPR of NH₂ is determined based on the fluorescence excitation model. Since the NH₂ is a photodissociation product of cometary ammonia, we applied the permutation group theory to the whole reaction system (i.e. the photodissociation reaction of ammonia to NH₂ and H) in order to derive the OPR of ammonia from that of NH₂. The derived OPR of ammonia is 1.12 ± 0.03 in Comet C/2001 A2 (LINEAR). This value corresponds to a spin temperature of 30⁺³ _-2 K. If this reflects the temperature where the comet formed in the protosolar nebula, our result indicates that thiscomet was formed in the region of the giant planets between Jupiter and Neptune.  相似文献   

Near Real－Time Calculation of Ionospheric Electric Fields and Currents Using GEDAS     

H.Shirai  Y.Kamide  E.A.Kihn  B.Hausman  M.Shinohara  H.Nakata  M.Isowa  T.K.Takada  Y.Watanabe  S.Masuda 《中国天文和天体物理学报》2003,3(4):375-380

This paper presents the recent progress in our project of estimating near real-time electric fields and currents in the ionosphere through our computer system called the Geospace Environment Data Analysis System (GEDAS). We show a new technique in which data from ground magnetometers are collected by the system and used as input for the KRM and AMIE programs to calculate the distribution of ionospheric electric fields and currents, as well as of other ionospheric parameters, such as electric potential patterns. One of the goals of this project is to specify ionospheric processes. Examples of the near real-time calculation and the data flow of our scheme are presented.  相似文献   

YOHKOH/WBS Recalibration and a Comprehensive Catalogue of Solar Flares Observed by YOHKOH SXT, HXT and WBS Instruments     

J. Sato  Y. Matsumoto  K. Yoshimura  S. Kubo  J. Kotoku  S. Masuda  M. Sawa  K. Suga  M. Yoshimori  T. Kosugi  T. Watanabe 《Solar physics》2006,236(2):351-368

The flare catalogue of the Yohkoh mission is compiled and linked to this article as an electronic supplement. For showing flare characteristics over wide energy range concisely, we provide the images of Hard X-ray Telescope (HXT) and the Soft X-ray Telescope (SXT), and the spectra of Hard X-ray Spectrometer (HXS) and Gamma-Ray Spectrometer (GRS) with the Wide Band Spectrometer (WBS) time profiles. The energy versus pulse height (PH) data channels in HXS and GRS are re-calibrated by using the data of the whole mission period. Secular gain changes are recognized in HXS, and the characteristics of power-law flare spectra simultaneously observed by HXT and HXS confirms the trend. The GRS gains are different for the flare observations during the previous maximum and for the current maximum. The total of 33 γ -ray events are observed, and for 12 of them γ-ray flare spectra are obtained. Electronic supplementary material to this article is available at and is accessible for authorized users.  相似文献   

Estimation of freshwater and material fluxes from the Yangtze River into the East China Sea by using TOPEX/Poseidon altimeter data     

Jiqun Zhang  Kaiqin Xu  Lianhui Qi  Yonghui Yang  Masataka Watanabe 《水文研究》2005,19(18):3683-3698

In order to determine material fluxes in rivers by non‐contact methods, it is essential to estimate river discharge first. Although developed and optimized for open oceans, satellite radar altimetry has the potential to monitor variations in the levels of inland waters such as lakes and rivers. Making use of the concept of an ‘assumed reference point’, we converted TOPEX/Poseidon satellite altimetry data on water level variations in the Yangtze River (Changjiang) to ‘water level’ data. We also used ‘water level’ time‐series data and in situ river discharge to establish a rating curve. By use of the rating curve, we converted data on ‘water level’ derived from 7 years (1993–99) of TOPEX/Poseidon data to actual river discharge. On the basis of statistical correlation between discharge and nutrient concentration data collected in 1987–88 and in 1998–99, we estimated the total amounts of freshwater and material fluxes transferred by the Yangtze River during the 1990s. The result reveals that an overall, but very slight, increase in freshwater and material fluxes occurred during the 1990s. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献