Assessment of drought frequency, duration, and severity and its impact on pasture production in Mongolia   总被引：1，自引：1，他引：0  

Banzragch Nandintsetseg  Masato Shinoda 《Natural Hazards》2013,66(2):995-1008

Drought frequency, duration, and severity and its impact on pasture productivity in the four main vegetation zones of Mongolia were analyzed using meteorological, soil moisture, and vegetation data during the growing season (April–August) of 1965–2010. Meteorological and pasture drought characteristics were explored using the Standardized Precipitation Index (SPI), the soil moisture anomalies percentile index (W _p), and Palmer Drought Severity Index (PDSI) on 1-month timescale. Generally, 35–37 (15–16 %) by SPI for meteorological drought while 27–29 (12–13 %) by W _p, and 16–21 (7–9 %) by PDSI for pasture drought with different durations were identified over the four vegetation zones during the study period. Most of these droughts (80 % by SPI and 50–60 % by both W _p and PDSI) observed during the entire events occurred on a 1-month duration with moderate intensity. Drought frequencies were not significantly (p > 0.05) different within the four zones. The frequency of the short-term meteorological droughts was observed relatively greater than pasture droughts; however, pasture droughts were more persistent and severe than meteorological droughts. The three indices show that the frequency and severity of droughts have slightly increased over the 46 years with significant (p < 0.05) dry conditions during the last decade of 2001–2010 in the four zones (except in the high mountain). The results showed the W _p was more highly significantly correlated with the precipitation anomalies (r = 0.68) and pasture production (r = 0.55) than PDSI (r = 0.51, p < 0.05 and r = 0.38, p < 0.10, respectively). A statistical model, based on pasture production and the W _p, suggested that the consecutive drought months contribution during the growing season was 30 % (p < 0.05) and that pasture production was more sensitive to the occurrence of droughts during June–August (R ² = 0.32, p < 0.05) as seen in 2000–2002 and 2007. We concluded that a greater severity and frequency of growing-season droughts, during the last decade of 2001–2010, have driven a reduction in pasture production in Mongolia.  相似文献   

Characteristic features in Venus’ nightside cloud-top temperature obtained by Akatsuki/LIR     

Makoto Taguchi  Tetsuya Fukuhara  Masahiko Futaguchi  Mitsuteru Sato  Takeshi Imamura  Kazuaki Mitsuyama  Masato Nakamura  Munetaka Ueno  Makoto Suzuki  Naomoto Iwagami  George L. Hashimoto 《Icarus》2012,219(1):502-504

Mid-infrared images of almost the entire Venus nightside hemisphere obtained by the Longwave Infrared Camera (LIR) onboard Akatsuki on December 9 and 10, 2010 reveal that the brightness temperature of the cloud-top ranges from 237 K in the cold polar collars to 243 K in the equatorial region, significantly higher than the values obtained by Venera 15. Other characteristic features of the temperature distributions observed are zonal belt structures seen in the middle and low latitudes and patchy temperature structures or quasi-periodic streaks extending in a north–south direction in the northern middle latitudes and southern low latitudes.  相似文献   

南海夏季风爆发的气候特征   总被引：8，自引：4，他引：8  

刘霞  谢安  叶谦  Masato Murakami 《热带气象学报》1998,14(1):28-37

利用ＴＯＧＡ－ＣＯＡＲＥ强化期“实验３”号科学考究船所取得的表面气象的探空资料,对考察期间的热通量进行详尽的分析和计算,特别是对发生在ＩＯＰ期间的两次西风爆发过程中西太平洋热带海域热通量的特征进行了重点分析,并讨论了它们与大尺度环流及其中高纬度环流的关系。  相似文献   

The nationwide investigation of endocrine disruptors in sediment of harbours   总被引：3，自引：0，他引：3  

Hosokawa Y  Yasui M  Yoshikawa K  Tanaka Y  Suzuki M 《Marine pollution bulletin》2003,47(1-6):132-138

Various types of endocrine disruptors or environmental hormones flow from their sources down into harbours through rivers and other watercourses, and are accumulated in sediment on the sea bottom. Tributyltin, which has been used as paint for ship bottoms, is considered one of the endocrine disruptors.In close cooperation with the other ministries and agencies, the Ports and Harbours Bureau of the Ministry of Land, Infrastructure and Transport carried out an investigation in 1999 to determine the actual condition of 12 endocrine disruptors in the sediment of 39 harbours, in order to gather fundamental data to be used in future examinations of policy. Furthermore, in 2000 the bureau chose seven harbours out of the above 39 harbours as subjects of an additional investigation regarding the surface distribution of endocrine disruptors in the harbour areas and the synchronistic change of accumulation of dioxin and other substances. As the result of the investigation regarding the surface distribution of endocrine disruptors accumulated in seven harbours, relatively high concentrations were measured in the innermost parts of harbours and the mouths of rivers. Synchronistic changes in the amount of dioxin and other substances accumulated in sediments of five harbours were determined. Small amounts of dioxin and other substances, including an especially small amount of coplanar-PCBs, were found in the layers formed before or around 1950. Relatively large amounts of these substances were measured in the upper layers formed during roughly 1960-1990, though no significant yearly differences in concentration could be identified. This result coincides with the facts that, during roughly 1960-1980, PCP and CNP were used as agricultural chemicals and full-scale production of PCBs started in 1960.  相似文献   

Estimation of methane emission from whole waste landfill site using correlation between flux and ground temperature   总被引：1，自引：0，他引：1  

Tomonori Ishigaki  Masato Yamada  Masanao Nagamori  Yusaku Ono  Yuzo Inoue 《Environmental Geology》2005,48(7):845-853

A methodology to estimate a methane emission in a waste landfill site was developed. The methane flux at a waste landfill site in summer, autumn, and winter was within the following ranges: from −1.3×10⁻² to 16, from −6.4×10⁻² to 7.5, and from −1.6×10⁻³ to 1.5×10⁻² g-CH₄ m⁻² h⁻¹, respectively. In those seasons, the mean methane emission rate and coefficient of variation were 1.1 g-CH₄ m⁻² h⁻¹ ±290%, 0.57 g-CH₄ m⁻² h⁻¹ ±347%, and 5.4×10⁻² g-CH₄ m⁻² h⁻¹ ±370%, respectively. These results simultaneously showed that fluctuations of methane emission from the landfill surface were both of spatial and temporal variability. In each season, an exponential relationship was observed between the methane flux density and the ground temperature. Total methane emissions were estimated to be 5.7×10⁻², 7.1×10⁻³, and 1.7×10⁻³ g-CH₄ m⁻² h⁻¹ in the summer, autumn, and winter surveys, respectively, using a temperature surrogated-kriging method. The results of this study would improve upon the labor-intensive closed-chamber method, and could be a more practical way to estimate methane emissions from waste landfills.  相似文献   

The effects of torsion and motion coupling in site response estimation     

Mohammad R. Ghayamghamian  Masato Motosaka 《地震工程与结构动力学》2003,32(5):691-709

Soil amplification characteristics are investigated using data from the Chibaken‐Toho‐Oki earthquake and its aftershocks recorded at Chiba dense array in Japan. The frequency‐dependent amplification function of soil is calculated using uphole‐to‐downhole spectral ratio analysis, considering the horizontal components of shear wave. The identified spectral ratios consistently demonstrate the splitting of peaks in their resonance frequencies and low amplification values in comparison with a 1D model. The torsional behaviour and horizontal ground motion coupling are clarified as the reasons for these phenomena at the site. To prove the hypothesis, the torsional motion is directly evaluated using the data of the horizontal dense array in different depths at the site. The comparison between Fourier spectra of torsional motion and identified transfer functions reveals the peaks at the same frequencies. The wave equation including torsion and horizontal motion coupling is introduced and solved for the layered media by applying wave propagation theory. Using the developed model, the effects of torsional motion with horizontal motion coupling on soil transfer function are numerically examined. Splitting and low amplification at resonance frequencies are confirmed by the results of numerical analysis. Furthermore, the ground motion in two horizontal directions at the site is simulated using site geotechnical specification and optimizing the model parameters. The simulated and recorded motions demonstrate good agreement that is used to validate the hypothesis. In addition, the spectral density of torsional ground motions are compared with the calculated one and found to be well predicted by the model. Finally, the results are used to explain the overestimation of damping in back‐calculation of dynamic soil properties using vertical array data in small strain level. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

The Nobeyama Millimeter Array Survey for protoplanetary disks around protostar candidates and T Tauri stars in Taurus     

Nagayoshi Ohashi  Ryohei Kawabe  Masato Ishiguro  Masahiko Hayashi 《Astrophysics and Space Science》1994,212(1-2):239-250

The Nobeyama Millimeter Array Survey for protoplanetary disks has been made for 19 protostellar IRAS sources in Taurus; 13 of them were optically invisible protostars and 6 were young T Tauri stars. We observed 98-GHz continuum and CS(J = 2 – 1) line emissions simultaneously with spatial resolutions of 2 _. 8-8 _. 8 (360-1,200 AU). The continuum emission was detected from 5 out of 6 T Tauri stars and 2 out of 13 protostar candidates: the emission was not spatially resolved and was consistent with being originated from compact circumstellar disks. Extended CS emission was detected around 2 T Tauri stars and 11 protostar candidates. There is a remarkable tendency for the detectability of the 98-GHz continuum emission to be small for protostar candidates. This tendency is explained if the mass of protoplanetary disks around protostars is not as large as that around T Tauri stars; the disk mass may increase with the increase of central stellar mass by dynamical accretion in the course of evolution from protostars to T Tauri stars.Paper presented at the Conference onPlanetary Systems: Formation, Evolution, and Detection held 7–10 December, 1992 at CalTech, Pasadena, California, U.S.A.  相似文献   

The switching between zonal and blocked mid-latitude atmospheric circulation: a dynamical system perspective     

Davide Faranda  Giacomo Masato  Nicholas Moloney  Yuzuru Sato  Francois Daviaud  Bérengère Dubrulle  Pascal Yiou 《Climate Dynamics》2016,47(5-6):1587-1599

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Evaluation of pounding countermeasures and serviceability of elevated bridges during seismic excitation using 3D modeling     

Ping Zhu  Masato Abe  Yozo Fujino 《地震工程与结构动力学》2004,33(5):591-609

This paper conducts elaborate analyses to evaluate the effectiveness of pounding countermeasures and the serviceability of elevated bridges subject to severe ground motions using detailed 3‐dimensional non‐linear modeling of an entire bridge structure system. A three‐span elevated steel bridge is selected for a case study. The peak and residual magnitude of gaps between girders and the maximum shear deformations of bearings are computed and used in the serviceability evaluation. The results show that under proper configurations the mitigation devices work effectively in reducing pounding actions in both the longitudinal and rotational directions. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Inclined single piles under vertical loadings in cohesionless soil     

Goit  Chandra Shekhar  Saitoh  Masato  Igarashi  Takumi  Sasaki  Shun 《Acta Geotechnica》2021,16(4):1231-1245

Physical-scaled model testing under 1 g conditions is carried out in obtaining the vertical response of fixed head floating-inclined single piles embedded in dry sand. Practical pile inclinations of 5° and 10° besides a vertical pile (0°) subjected to static and dynamic vertical pile head loadings are considered. To account for the effects of soil nonlinearity as well as the soil–pile interface nonlinearity on the response of piles, a range of low-to-high magnitude of pile head displacements is considered for the static case while a varying amplitude of harmonic accelerations for a wide range of frequencies is considered for the dynamic case. Experimental results are obtained in the form of pile head stiffnesses and strains generated in the pile under both the static and dynamic loadings. Results suggest that the nonlinear behavior of soil as well as the nonlinearity generated at the interface between the soil and the pile as the result of applied loading considerably affect the response of piles. The soil–pile interface nonlinearity that governs the slippage of pile shows a clear influence on the pile head stiffnesses by providing two distinct values of stiffnesses corresponding to the push and the pull directional movement of piles; the two values are significantly different. Axial and bending strains generated in the piles show expected dependency on the amplitude of applied loading; the pile head-level bending strain increases almost linearly with the increase in the angle of pile inclination.

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