Frost heave analysis of ballasted track above box culvert and its influence on train vibration     

Bin Luo  Hao Lai  Tatsuya Ishikaw  Tetsuya Tokoro 《寒旱区科学》2017,9(3):229-235

The uneven frost heave of frost-susceptible subgrade soil causes track irregularity, which highly enhances train vibration and affects the comfort and safety of railway transportation. This paper presents a coupled thermo-hydro-mechanical (THM) analysis for the freezing behavior of railway located above a box culvert. The vertical acceleration of the vehicle, an indicator of riding comfort, is predicted through a vehicle dynamic model. The results reveal that the existence of a box culvert changes the subgrade thermal pattern, leading to a deeper frost penetration depth. The frost heave amount above the box culvert is larger than the adjacent section, resulting in uneven track structure upheave and track irregularity. This frost-induced track irregularity highly affects train vibration.  相似文献   

Evidence for the significant role of sea surface temperature distributions over remote tropical oceans in tropical cyclone intensity     

Anitha Kumari Hegde  Ryuichi Kawamura  Tetsuya Kawano 《Climate Dynamics》2016,47(1-2):623-635

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Evaluation of air-sea sensible and latent heat fluxes over the Japan Sea obtained from satellite,atmospheric reanalysis,and objective analysis products     

Hiroyuki Tomita  Tomoharu Senjyu  Masahisa Kubota 《Journal of Oceanography》2016,72(5):747-760

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Preface to the Special Issue on Summer 2020: Record Rainfall in Asia — Mechanisms,Predictability and Impacts     

Robin T.CLARK  Xiquan DONG  Chang-Hoi HO  Jianhua SUN  Huiling YUAN  Tetsuya TAKEMI 《大气科学进展》2021,38(12):1977-1979

Throughout vast areas of Asia, the summer of 2020 was extraordinarily wet. After an exceptionally wet May in North-east India and Bangladesh, excessive rainfall hit at least 10 provinces in central and southern China in June and July, caus-ing extensive flooding in many rural and urban locations. Long standing rainfall, lake and river level records were con-sequently broken in several parts of the region with the Yangtze-Huaihe river valleys, particularly badly impacted, with con-sequential economic losses. Floods and landslides also affected parts of Japan with at least one location in Kumamoto province even experiencing a record-breaking 1000 mm of rainfall in just 3 days in early July. The 2020 wet season in South Korea was also exceptionally long, lasting 54 days, compared to their more usual 32.  相似文献   

Reconstructions of annual discharge and equilibrium line altitude of glaciers at Qilian Shan,northwest China,from 1978 to 2002     

Akiko Sakai  Koji Fujita  Chiyuki Narama  Jumpei Kubota  Masayoshi Nakawo  Tandong Yao 《水文研究》2010,24(19):2798-2806

Discharge was calculated from a mountainous area, including discharge from glaciers, in the Qilian Shan (Qilian Mountains) of northwest China. The studied Yingluoxia basin is 9983 km² in area, with glaciers making up 0·3% of the basin. The calculation method was based on the heat balance, requiring only daily temperature and precipitation. Calculated annual discharge from the basin corresponded well with the observed data. Calculated annual discharge from glaciers was 3·6% of the total discharge from the basin. The temporal trend of the calculated equilibrium line altitude (ELA) at the July 1st Glacier (western side of the Yingluoxia basin) was similar to that of the observed ELA. The calculated annual mass balance of glaciers within the Yingluoxia basin has a larger negative value than the other glaciers in China, as the ratio of accumulation area to the total glacier area in the Yingluoxia basin is much lower than in neighbouring basins to the west. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Surface energy partitioning and evapotranspiration over a double‐cropping paddy field in Bangladesh     

Md. Shahadat Hossen  Masayoshi Mano  Akira Miyata  Md. Abdul Baten  Tetsuya Hiyama 《水文研究》2012,26(9):1311-1320

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An eddy-resolving simulation of the diurnal variation of fair-weather convection and tracer transport     

Tetsuya Takemi   《Atmospheric Research》2008,89(3):270-282

Tracer transport in the atmosphere is controlled not only by synoptic-scale to mesoscale weather disturbances but also by microscale boundary-layer processes especially under fair-weather conditions. The present study investigates numerically the diurnal variation of boundary-layer convection and cumulus clouds and their role in transporting tracers by conducting high-resolution simulations that explicitly resolve turbulent eddies. The transport of dust aerosols in a desert area under two distinct stability conditions is specifically examined. Convection plays a significant role in transporting dust upward; in other words, the vertical depth of the dust transport is critically determined by the depth of convection. Deep convection is effective in transporting dust into the free atmosphere. The early morning stratification strongly regulates the temporal evolution and the vertical growth of convection and therefore the amount of tracer emission and transport. A sensitivity to model resolution of O (1 km) in a cloud-resolving simulation range is also examined. A proper parameterization for activating microscale convection is required for representing the diurnal variation of convection and tracer transport.  相似文献   

Impact of seas/lakes on polar meteorology of Titan: Simulation by a coupled GCM-Sea model   总被引：1，自引：0，他引：1  

Tetsuya Tokano 《Icarus》2009,204(2):619-636

The detection of large hydrocarbon seas/lakes near the poles by the Cassini spacecraft raises the question as to whether and how polar seas affect the meteorology on Titan. The polar meteorology and methane hydrological cycle in the presence of seas are investigated by a three-dimensional atmospheric general circulation model coupled to a one-dimensional sea energy balance model considering the observed sea/lake geography. The sea composition has a large control on the seasonal evolution of seas, temperature and wind system in the polar region, particularly in the north where large seas are located. The surface of ethane-rich seas, which do not evaporate methane, undergo a large seasonal temperature variation and the sea surface is often warmer than the surrounding land surface. Land breeze in summer towards the seas causes a moisture convergence over the seas, which leads to enhanced summer precipitation in the sea area. On the other hand, methane-rich seas evaporate some methane and are therefore colder than the surroundings. This causes a sea breeze across the north pole in summer, which blows away the moisture from the polar region, so precipitation becomes scarce in the north polar region. The breeze can become stronger than the tidal wind. Sea evaporation peaks in winter, when the temperature and average methane mixing ratio in the planetary boundary layer become lowest. The sea level predominantly rises in summer by precipitation and retreats in winter by evaporation. The meteorology in the south polar region is less sensitive to the composition of the lakes because of the paucity and smallness of southern lakes. Lake-effect precipitation can occur either by moisture convergence by the breeze or humidity enhancement over the seas, but is more characteristic of warm seasons than of cold seasons.  相似文献   

A statistical method to get surface level air-temperature from satellite observations of precipitable water     

Pankajakshan Thadathil  Akira Shikauchi  Yasuhiro Sugimori  Masahisa Kubota 《Journal of Oceanography》1993,49(5):551-558

Ten-day mean surface level air-temperature from SSMI precipitable water (SSMI-T _a ) has been derived and compared with the temperature from two ocean data buoys (Buoy-T _a ) of Japan Meteorological Agency (JMA) for a period of six months (July–December, 1988). Statistical relations between air-temperature and mixing ratio, using data from ocean data buoys are used to derive air-temperature from mixing ratio, obtained from SSMI precipitable water. For getting the mixing ratio from precipitable water, regional mixing ratio-precipitable water relations have been used, instead of global relation proposed by Liu (1986). The rms errors (standard deviation of the difference between SSMI-T _a and Buoy-T _a ) for two buoy locations are found to be 1.15 and 1.12°C, respectively. Surface level temperature for the two buoy locations are also derived using direct regression relation between Buoy-T _a and precipitable water. The rms errors of the SSMI-T _a , in this case are found to be reduced to 1.0°C.  相似文献   

拉萨上空大气臭氧垂直分布的高空气球探测   总被引：11，自引：0，他引：11  

石广玉  白宇波  岩坂泰信  大桥铁弥 《地球科学进展》2000,15(5):522-524

用臭氧探空仪于1998年8月和10月测量了在拉萨上空的臭氧垂直分布,并与河北香河的观测资料进行了对比。结果表明,拉萨上空对流层臭氧浓度较低,在25～26 km之间臭氧分压最大,在30～34 km之间混合比最大。从典型的臭氧垂直分布廓线推算出大气臭氧总含量为261.6DU。  相似文献