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Field Observations of Near-Surface Wind Flow Across Expressway Embankment on the Qinghai–Tibet Plateau
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作者 Yanhu Mu Wei Ma +3 位作者 Zhaohui(Joey)Yang Xiaolin Li Kun Zhang Yuncheng Mao 《Engineering》 SCIE EI CAS 2022年第7期169-180,共12页
Crushed rock layers(CRLs),ventilation ducts(VDs)and thermosyphons are air-cooling structures(ACSs)widely used for maintaining the long-term stability of engineered infrastructures in permafrost environments.These ACSs... Crushed rock layers(CRLs),ventilation ducts(VDs)and thermosyphons are air-cooling structures(ACSs)widely used for maintaining the long-term stability of engineered infrastructures in permafrost environments.These ACSs can effectively cool and maintain the permafrost subgrade’s frozen state under climate warming by facilitating heat exchange with ambient air in cold seasons.As convection is a crucial working mechanism of these ACSs,it is imperative to understand the near-surface wind flow(NSWF)across a constructed infrastructure,such as an embankment.This article describes a yearlong field observation of the NSWF across an experimental expressway embankment,the first of its kind on the Qinghai–Tibet Plateau(QTP).The wind speed and direction along a transect perpendicular to the embankment on both the windward and leeward sides and at four different heights above the ground surface were collected and analyzed.The results showed that the embankment has a considerable impact on the NSWF speed within a distance of up to ten times its height,and in the direction on the leeward side.A power law can well describe the speed profiles of NSWF across the embankment,with the power-law indices(PLIs)varying from 0.14 to 0.40.On an annual basis,the fitted NSWF PLI far away from the embankment was 0.19,which differs substantially from the values widely used in previous thermal performance evaluations of ACSs on the QTP.Finally,the significance of the NSWF to the thermal performance of the ACSs,particularly the CRLs and VDs,in linear transportation infrastructure is discussed.It is concluded that underestimating the PLI and neglecting wind direction variations may lead to unconservative designs of the ACSs.The results reported in this study can provide valuable guidance for infrastructure engineering on the QTP and other similar permafrost regions. 展开更多
关键词 Near-surface wind flow field observation Air-cooling structures Linear transportation infrastructure Qinghai–Tibet Plateau
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Dataset of Comparative Observations for Land Surface Processes over the Semi-Arid Alpine Grassland against Alpine Lakes in the Source Region of the Yellow River 被引量:2
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作者 Xianhong MENG Shihua LYU +13 位作者 Zhaoguo LI Yinhuan AO Lijuan WEN Lunyu SHANG Shaoying WANG Mingshan DENG Shaobo ZHANG Lin ZHAO Hao CHEN Di MA Suosuo LI Lele SHU Yingying AN Hanlin NIU 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2023年第6期1142-1157,共16页
Thousands of lakes on the Tibetan Plateau(TP) play a critical role in the regional water cycle, weather, and climate. In recent years, the areas of TP lakes underwent drastic changes and have become a research hotspot... Thousands of lakes on the Tibetan Plateau(TP) play a critical role in the regional water cycle, weather, and climate. In recent years, the areas of TP lakes underwent drastic changes and have become a research hotspot. However, the characteristics of the lake-atmosphere interaction over the high-altitude lakes are still unclear, which inhibits model development and the accurate simulation of lake climate effects. The source region of the Yellow River(SRYR) has the largest outflow lake and freshwater lake on the TP and is one of the most densely distributed lakes on the TP. Since 2011,three observation sites have been set up in the Ngoring Lake basin in the SRYR to monitor the lake-atmosphere interaction and the differences among water-heat exchanges over the land and lake surfaces. This study presents an eight-year(2012–19), half-hourly, observation-based dataset related to lake–atmosphere interactions composed of three sites. The three sites represent the lake surface, the lakeside, and the land. The observations contain the basic meteorological elements,surface radiation, eddy covariance system, soil temperature, and moisture(for land). Information related to the sites and instruments, the continuity and completeness of data, and the differences among the observational results at different sites are described in this study. These data have been used in the previous study to reveal a few energy and water exchange characteristics of TP lakes and to validate and improve the lake and land surface model. The dataset is available at National Cryosphere Desert Data Center and Science Data Bank. 展开更多
关键词 field observation dataset lake-atmosphere interaction energy and water exchanges the source region of the Yellow River Tibetan Plateau
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Magnetic Field Strengths and Structures from Radio Observations of Solar Active Regions 被引量:1
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作者 Chang-XiZhang G.B.Gelfreikh 《Chinese Journal of Astronomy and Astrophysics》 CSCD 北大核心 2002年第3期266-276,共11页
Radio observations of some active regions (ARs) obtained with the Nobeyama radioheliograph at λ=1.76 cm are used for estimating the magnetic field strength in the upper chromosphere, based on thermal bremsstrahlung. ... Radio observations of some active regions (ARs) obtained with the Nobeyama radioheliograph at λ=1.76 cm are used for estimating the magnetic field strength in the upper chromosphere, based on thermal bremsstrahlung. The results are compared with the magnetic field strength in the photosphere from observations with the Solar Magnetic Field Telescope (SMFT) at Huairou Solar Observing Station of Beijing Astronomical Observatory. The difference in the magnetic field strength between the two layers seems reasonable. The solar radio maps of active regions obtained with the Nobeyama radioheliograph, both in total intensity (I-map) and in circular polarizations (V-map), are compared with the optical magnetograms obtained with the SMFT. The comparison between the radio map in circular polarization and the longitudinal photospheric magnetogram of a plage region suggests that the radio map in circular polarization is a kind of magnetogram of the upper chromosphere. The comparison of the radio map in total intensity with the photo-spheric vector magnetogram of an AR shows that the radio map in total intensity gives indications of magnetic loops in the corona, thus we have a method of defining the coronal magnetic structure from the radio I-maps at λ=1.76 cm. Analysing the I-maps, we identified three components: (a) a compact bright source; (b) a narrow elongated structure connecting two main magnetic islands of opposite polarities (observed in both the optical and radio magnetograms); (c) a wide, diffuse, weak component that corresponds to a wide structure in the solar active region which shows in most cases an S or a reversed S contour, which is probably due to the differential rotation of the Sun. The last two components suggest coronal loops on different spatial scales above the neutral line of the longitudinal photospheric magnetic field. 展开更多
关键词 Sun: active regions - Sun: magnetic fields - Sun: optical observation - Sun: radio observation
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Sheltering effect of punched steel plate sand fences for controlling blown sand hazards along the Golmud-Korla Railway:Field observation and numerical simulation studies 被引量:4
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作者 ZHANG Kai TIAN Jianjin +2 位作者 QU Jianjun ZHAO Liming LI Sheng 《Journal of Arid Land》 SCIE CSCD 2022年第6期604-619,共16页
Sand fences made of punched steel plate(PSP)have recently been applied to control wind-blown sand in desertified and Gobi areas due to their strong wind resistance and convenient in situ construction.However,few studi... Sand fences made of punched steel plate(PSP)have recently been applied to control wind-blown sand in desertified and Gobi areas due to their strong wind resistance and convenient in situ construction.However,few studies have assessed the protective effect of PSP sand fences,especially through field observations.This study analyzes the effects of double-row PSP sand fences on wind and sand resistance using field observations and a computational fluid dynamics(CFD)numerical simulation.The results of field observations showed that the average windproof efficiencies of the first-row and second-row sand fences were 79.8%and 70.8%,respectively.Moreover,the average windproof efficiencies of the numerical simulation behind the first-row and second-row sand fences were 89.8%and 81.1%,respectively.The sand-resistance efficiency of the double-row PSP sand fences was 65.4%.Sand deposition occurred close to the first-row sand fence;however,there was relatively little sand on the leeward side of the second-row sand fence.The length of sand accumulation near PSP sand fences obtained by numerical simulation was basically consistent with that through field observations,indicating that field observations combined with numerical simulation can provide insight into the complex wind-blown sand field over PSP sand fences.This study indicates that the protection efficiency of the double-row PSP sand fences is sufficient for effective control of sand hazards associated with extremely strong wind in the Gobi areas.The output of this work is expected to improve the future application of PSP sand fences. 展开更多
关键词 punched steel plate sheltering effect field observations computational fluid dynamics numerical simulation windproof efficiency
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Field Observation and Analysis of Wave-Current-Sediment Movement in Caofeidian Sea Area in the Bohai Bay, China 被引量:5
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作者 左利钦 陆永军 +1 位作者 汪亚平 刘怀湘 《China Ocean Engineering》 SCIE EI CSCD 2014年第3期331-348,共18页
In order to study the mechanism of flow-sediment movement, it is essential to obtain measured data of water hydrodynamic and sediment concentration process with high spatial and temporal resolution in the bottom bound... In order to study the mechanism of flow-sediment movement, it is essential to obtain measured data of water hydrodynamic and sediment concentration process with high spatial and temporal resolution in the bottom boundary layer (BBL). Field observations were carried out in the northwest Caofeidian sea area in the Bohai Bay. Near 2 m isobath (under the lowest tidal level), a tripod system was installed with AWAC (Acoustic Wave And Current), ADCP (Acoustic Doppler Current Profilers), OBS-3A (Optical Backscatter Point Sensor), ADV (Acoustic Doppler Velocimeters), etc. The accurate measurement of the bottom boundary layer during a single tidal period was carried out, together with a long-term sediment concentration measurement under different hydrological conditions. All the measured data were used to analyze the characteristics of wave-current-sediment movement and the BBL. Analysis was performed on flow structure, shear stress, roughness, eddy viscosity and other parameters of the BBL. Two major findings were made. Firstly, from the measured data, the three-layer distribution model of the velocity profiles and eddy viscosities in the wave-current BBL are proposed in the observed sea area; secondly, the sediment movement is related closely to wind-waves in the muddy coast area where sediment is clayey silt: 1) The observed suspended sediment concentration under light wind conditions is very low, with the peak value generally smaller than 0.1 kg/m^3 and the average value being 0.03 kg/m^3; 2) The sediment concentration increases continuously under the gales over 6-7 in Beaufort scale, under a sustained wind action. The measured peak sediment concentration at 0.4 m above the seabed is 0.15-0.32 kg/m^3, and the average sediment concentration during wind-wave action is 0.08-0.18 kg/m^3, which is about 3-6 times the value under light wind conditions. The critical wave height signaling remarkable changes of sediment concentration is 0.5 m. The results show that the suspended load sediment concentration is mainly influenced by wave-induced sediment suspension. 展开更多
关键词 field observation wave-induced sediment suspension wave-current interaction bottom boundary layer (BBL) Caofeidian Bohai Bay
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Field observation of debris-flow activities in the initiation area of the Jiangjia Gully, Yunnan Province, China 被引量:3
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作者 YANG Hong-juan ZHANG Shao-jie +3 位作者 HU Kai-heng WEI Fang-qiang WANG Kai LIU Shuang 《Journal of Mountain Science》 SCIE CSCD 2022年第6期1602-1617,共16页
The Jiangjia Gully, which is located in Dongchuan District, Yunnan Province, China, is a watershed prone to debris flows and has long-term recorded data of debris-flow occurrence. However, the initiation mechanism has... The Jiangjia Gully, which is located in Dongchuan District, Yunnan Province, China, is a watershed prone to debris flows and has long-term recorded data of debris-flow occurrence. However, the initiation mechanism has mainly been studied by experiments in this watershed. To further reveal debris-flow formation mechanism in the Jiangjia Gully, debris-flow activities in the initiation zone were observed with hand-held video cameras in the summer of 2016 and 2017. In these two years, six debris-flow events were triggered in Menqian Gully, a major tributary of the Jiangjia Gully, while debrisflow activities in some sub-watersheds of Menqian Gully were recorded with video cameras in four events. The video recording shows that landslides constituted an important source for sediment supply in debris flow. Some landslides directly evolved into debris flows, while the others released sediment into rills and channels, where debris flows were generated for sediment entrainment by water flow. Therefore, debris-flow occurrence in the Jiangjia Gully is influenced both by infiltration-dominated processes and by runoff-dominated processes. In addition, rainfall data from four gauges installed in Menqian Gully were analyzed using mean intensity(I), duration(D), peak 10-minute rainfall(R10min) and antecedent rainfall(AR) up to 15 days prior to peak 10-minute rainfall. It reveals that debris-flow triggering events can be discriminated from nontriggering events either by an I-D threshold or by an R10min-AR threshold. However, false alarms can be greatly reduced if these two kinds of thresholds are used together. Moreover, behaviors including intermittency of debris flow, variance in moisture content and volume among surges, and coalescence of multiple surges by temporary damming were observed, indicating the complexity of debris-flow initiation processes. These findings are expected to enhance our knowledge on debris-flow formation mechanism in regions with similar environmental settings. 展开更多
关键词 Debris flow field observation Initiation mechanism Rainfall threshold Jiangjia gully
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The Long-Term Field Experiment Observatory and Preliminary Analysis of Land-Atmosphere Interaction over Hilly Zone in the Subtropical Monsoon Region of Southern China 被引量:2
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作者 LIU Jian-Guo XIE Zheng-Hui +8 位作者 JIA Bing-Hao TIAN Xiang-Jun QIN Pei-Hua ZOU Jing YU Yan SUN Qin WANG Yuan-Yuan XIE Jin-Bo XIE Zhi-Peng 《Atmospheric and Oceanic Science Letters》 CSCD 2013年第4期203-209,共7页
To improve current understanding of the water cycle,energy partitioning and CO2 exchange over hilly zone vegetative land surfaces in the subtropical monsoon environment of southern China,a long-term field experiment o... To improve current understanding of the water cycle,energy partitioning and CO2 exchange over hilly zone vegetative land surfaces in the subtropical monsoon environment of southern China,a long-term field experiment observatory was set up at Ningxiang,eastern Hunan Province.This paper presents a preliminary analysis of the field observations at the observatory collected from August to November 2012.Results show that significant diurnal variations in soil temperature occur only in shallow soil layers(0.05,0.10,and 0.20 m),and that heavy rainfall affects soil moisture in the deep layers(≥ 0.40 m).During the experimental period,significant diurnal variations in albedo,radiation components,energy components,and CO2 flux were observed,but little seasonal variation.Strong photosynthesis in the vegetation canopy enhanced the CO2 absorption and the latent heat released in daylight hours;Latent heat of evaporation was the main consumer of available energy in late summer.Because the field experiment data are demonstrably reliable,the observatory will provide reliable long-term measurements for future investigations of the land-atmosphere interaction over hilly land surfaces in the subtropical monsoon region of southern China. 展开更多
关键词 field observation subtropical monsoon reion hilly zone surface flux land-atmosohere interaction
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The impact of social capital on children's (6–12) use of ICT in urban communities: A field survey from Zhengzhou City, Henan Province
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作者 Ping WANG Shang HUANG +1 位作者 Miao MIAO Tingting LI 《Chinese Journal of Library and Information Science》 2015年第4期50-61,共12页
Purpose: This paper focuses on the impact of social capital on urban children's use behavior of information communication technology (ICT).Design/methodology/approach: Using the field survey and in-depth intervie... Purpose: This paper focuses on the impact of social capital on urban children's use behavior of information communication technology (ICT).Design/methodology/approach: Using the field survey and in-depth interviews, we interviewed 40 children aged 6 to 12 and their parents from a staff residential quarter of the Zhengzhou University--"Shengheyuan" community (SHY), and a commercial residential quarter--"Wanfenghuicheng" community (WFHC) in the high-tech zone of Zhengzhou City, Henan Province. We used the social capital theory to analyze the interviewees' record.Findings: In urban communities, social capital is the most important factor for children (aged 6 to 12) in their ICT use. Our findings indicate that children in families with higher levels of social capital, such as internal resources, family income, parent educational backgrounds and parents' social network, have more-highly developed ICT skills. Personal motivation and obstacles, such as lack of access to computers on a regular basis, also have an impact on children's ICT use. External social capital, including schools, libraries, and public service institutes, have little impact on children's ICT use, if not combined with internal social capital factors.Research limitations: Our research samples were collected from two communities within the same city, which may influence the generalization of this research result.Originality/value: To explore the social capital's influence on children's ICT use, we used field observation for ICT use of children aged 6 to 12 in urban communities in China, and studied the children's ICT behavior from the perspective of internal and external social capital. 展开更多
关键词 Social capital Children aged 6 to12 Information communication technology field observation Community informatics
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The increased storage of suspended particulate matter in the upper water of the tropical Western Pacific during the 2015/2016 super El Nino event 被引量:2
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作者 Wei GAO Zhenyan WANG +1 位作者 Xuegang LI Haijun HUANG 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2021年第5期1675-1689,共15页
The climate variability induced by the El Nino-Southern Oscillation(ENSO)cycle drives significant changes in the physical state of the tropical Western Pacific,which has important impacts on the upper ocean carbon cyc... The climate variability induced by the El Nino-Southern Oscillation(ENSO)cycle drives significant changes in the physical state of the tropical Western Pacific,which has important impacts on the upper ocean carbon cycle.During 2015-2016,a super El Nino event occurred in the equatorial Pacific.Suspended particulate matter(SPM)data and related environmental observations in the tropical Western Pacific were obtained during two cruses in Dec.2014 and 2015,which coincided with the early and peak stages of this super El Nino event.Compared with the marine environments in the tropical Western Pacific in Dec.2014,an obviously enhanced upwelling occurred in the Mindanao Dome region;the nitrate concentration in the euphotic zone almo st tripled;and the size,mass concentration,and volume concentration of SPM obviously increased in Dec.2015.The enhanced upwelling in the Mindanao Dome region carried cold but eutrophic water upward from the deep ocean to shallow depths,even into the euphotic zone,which disrupted the previously N-limited conditions and induced a remarkable increase in phytoplankton blooms in the euphotic zone.The se results reveal the mechanism of how nutrient-limited ecosystems in the tropical Western Pacific respond to super El Nino events.In the context of the ENSO cycle,if predicted changes in biogenic particles occur,the proportion of carbon storage in the tropical Western Pacific is estimated to be increased by more than 52%,ultimately affecting the regional and possibly even global carbon cycle.This paper highlights the prospect for long-term prediction of the impact of a super El Nino event on the global carbon cycle and has profound implications for understanding El Nino events. 展开更多
关键词 suspended particulate matter field observations tropical Western Pacific 2015/2016 super E1 Nino event ocean carbon cycle
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Improved strategy for estimating stem volume and forest biomass using moderate resolution remote sensing data and GIS 被引量:10
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作者 Arief Wijaya Sandi Kusnadi +1 位作者 Richard Gloaguen Hermann Heilmeier 《Journal of Forestry Research》 SCIE CAS CSCD 2010年第1期1-12,I0001,共13页
This study presents the utility of remote sensing (RS), GIS and field observation data to estimate above ground biomass (AGB) and stem volume over tropical forest environment. Application of those data for the mod... This study presents the utility of remote sensing (RS), GIS and field observation data to estimate above ground biomass (AGB) and stem volume over tropical forest environment. Application of those data for the modeling of forest properties is site specific and highly uncertain, thus further study is encouraged. In this study we used 1460 sampling plots collected in 16 transects measuring tree diameter (DBH) and other forest properties which were useful for the biomass assessment. The study was carded out in tropical forest region in East Kalimantan, Indo- nesia. The AGB density was estimated applying an existing DBH - biomass equation. The estimate was superimposed over the modified GIS map of the study area, and the biomass density of each land cover was calculated. The RS approach was performed using a subset of sample data to develop the AGB and stem volume linear equation models. Pearson correlation statistics test was conducted using ETM bands reflectance, vegetation indices, image transform layers, Principal Component Analysis (PCA) bands, Tasseled Cap (TC), Grey Level Co-Occurrence Matrix (GLCM) texture features and DEM data as the predictors. Two linear models were generated from the significant RS data. To analyze total biomass and stem volume of each land cover, Landsat ETM images from 2000 and 2003 were preprocessed, classified using maximum likelihood method, and filtered with the majority analysis. We found 158±16 m^3.ha^-1 of stem volume and 168±15 t.ha^-1 of AGB estimated from RS approach, whereas the field measurement and GIS estimated 157±92 m^3.ha^-1 and 167±94 t.ha^-1 of stem volume and AGB, respectively. The dynamics of biomass abundance from 2000 to 2003 were assessed from multi temporal ETM data and we found a slightly declining trend of total biomass over these periods. Remote sensing approach estimated lower biomass abundance than did the GIS and field measurement data. The earlier approach predicted 10.5 Gt and 10.3 Gt of total biomasses in 2000 and 2003, while the later estimated 11.9 Gt and 11.6 Gt of total biomasses, respectively. We found that GLCM mean texture features showed markedly strong correlations with stem volume and biomass. 展开更多
关键词 above ground biomass stem volume remote sensing GIS field observation data
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Local scour at offshore windfarm monopile foundations: A review 被引量:7
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作者 Da-wei Guan Yu-xuan Xie +3 位作者 Zi-shun Yao Yee-Meng Chiew Ji-sheng Zhang Jin-hai Zheng 《Water Science and Engineering》 EI CAS CSCD 2022年第1期29-39,共11页
In this article,current research findings of local scour at offshore windfarm monopile foundations are presented.The scour mechanisms and scour depth prediction formulas under different hydrodynamic conditions are sum... In this article,current research findings of local scour at offshore windfarm monopile foundations are presented.The scour mechanisms and scour depth prediction formulas under different hydrodynamic conditions are summarized,including the current-only condition,wave-only condition,combined wave-current condition,and complex dynamic condition.Furthermore,this article analyzes the influencing factors on the basis of classical equations for predicting the equilibrium scour depth under specific conditions.The weakness of existing researches and future prospects are also discussed.It is suggested that future research shall focus on physical experiments under unsteady tidal currents or other complex loadings.The computational fluid dynamics-discrete element method and artificial intelligence technique are suggested being adopted to study the scour at offshore windfarm foundations. 展开更多
关键词 Offshore windfarm Monopile foundation Scour mechanisms Scour depth prediction Numerical modeling field observation Artificial intelligence Literature review
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On-line Measurement of Water-Soluble Ions in Ambient Particles 被引量:5
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作者 温天雪 王跃思 +1 位作者 张士昱 刘广仁 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2006年第4期586-592,共7页
Combining the system of rapid collection of ambient particles and ion chromatography, the system of rapid collection of fine particles and ion chromatography (RCFP-IC) was established to automatically analyze on-lin... Combining the system of rapid collection of ambient particles and ion chromatography, the system of rapid collection of fine particles and ion chromatography (RCFP-IC) was established to automatically analyze on-line the concentrations of water-soluble ions in ambient particles. Here, the general scheme of RCFP-IC is described and its basic performance is tested. The detection limit of RCFP-IC for SO4^2-, NO3^-, NO2^-, Cl^- and F- is below 0.3μg m^-3. The collection efficiency of RCFP-IC increases rapidly with increasing sized particles. For particles larger than 300 nm, the collection efficiency approaches 100%. The precision of RCFP-IC is more than 90% over 28 repetitions. The response of RCFP-IC is very sensitive and no obvious cross-pollution is found during measurement. A comparison of RCFP-IC with an integrated filter measurement indicates that the measurement of RCFP-IC is comparable in both laboratory experiments and field observations. The results of the field experiment prove that RCFP-IC is an effective on-line monitoring system and is helpful in source apportionment and pollution episode monitoring. 展开更多
关键词 RCFP-IC water-soluble ions ON-LINE basic performance field observation
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In-situ experiment investigations of hydrothermal process of highway in deep seasonal frozen soil regions of Inner Mongolia, China 被引量:5
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作者 ZHANG Hong-wei WANG Xue-ying +1 位作者 ZHAO Xin LIU Peng-fei 《Journal of Central South University》 SCIE EI CAS CSCD 2020年第7期2082-2093,共12页
To reveal the influencing factors and changing rules for the hydrothermal interaction process of highway subgrade, the field measurements of Shiwei-Labudalin Highway in Inner Mongolia, China was conducted for 3 years,... To reveal the influencing factors and changing rules for the hydrothermal interaction process of highway subgrade, the field measurements of Shiwei-Labudalin Highway in Inner Mongolia, China was conducted for 3 years, based on which the freezing-thawing rules and water content changing characteristics were analyzed. The main results show the subgrade presents a frequent freezing-thawing alternation, and the water content of subgrade exhibits an obvious seasonal alternation. The subbase has the maximum water content, while the base has the minimum water content. The change of water flux is concentrated in the thawing period and consistent with the change of temperature gradient. The subbase layer has the most active water flux due to the heat absorption and impermeability of pavement that easily causes the water accumulation in this layer. Therefore, the prevention and treatment for the freezing-thawing disease should be started from heat insulation and water resistance. 展开更多
关键词 subgrade engineering hydrothermal process field observation seasonal frozen soil regions freezing-thawing disease
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Remote Sensing Parameterization of Land Surface Heat Fluxes over Arid and Semi-arid Areas 被引量:5
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作者 马耀明 王介民 +6 位作者 黄荣辉 卫国安 MassimoMENENTI 苏中波 胡泽勇 高峰 文军 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2003年第4期530-539,共10页
Dealing with the regional land surfaces heat fluxes over inhomogeneous land surfaces in arid and semi-arid areas is an important but not an easy issue. In this study, one parameterization method based on satellite rem... Dealing with the regional land surfaces heat fluxes over inhomogeneous land surfaces in arid and semi-arid areas is an important but not an easy issue. In this study, one parameterization method based on satellite remote sensing and field observations is proposed and tested for deriving the regional land surface heat fluxes over inhomogeneous landscapes. As a case study, the method is applied to the Dunhuang experimental area and the HEIFE (Heihe River Field Experiment, 1988-1994) area. The Dunhuang area is selected as a basic experimental area for the Chinese National Key Programme for Developing Basic Sciences: Research on the Formation Mechanism and Prediction Theory of Severe Climate Disaster in China (G1998040900, 1999-2003). The four scenes of Landsat TM data used in this study are 3 June 2000, 22 August 2000, and 29 January 2001 for the Dunhuang area and 9 July 1991 for the HEIFE area. The regional distributions of land surface variables, vegetation variables, and heat fluxes over inhomogeneous landscapes in arid and semi-arid areas are obtained in this study. 展开更多
关键词 land surface heat flux arid and semi-arid area Landsat TM field observation
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Progress in Marine Meteorology Studies in China during 1999-2002 被引量:3
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作者 王东晓 秦曾灏 施平 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2004年第3期485-496,共12页
The progresses of marine meteorology studies achieved in China during the four year period from 1999 to 2002 are summarized in six directions: air-sea flux, marine meteorology in high latitudes, marine disasters, conn... The progresses of marine meteorology studies achieved in China during the four year period from 1999 to 2002 are summarized in six directions: air-sea flux, marine meteorology in high latitudes, marine disasters, connection between ocean and weather/climate in China, remote sensing applications and new methodologies in marine meteorology. Compared to the previous ones, these studies adopted much more first-hand datasets, and more scientific issues were involved. As an exciting remark, there were so many contributions done by the young scientists. A brief statement about the research strategy of marine meteorology in China for the coming years is also given. 展开更多
关键词 marine meteorology China field observation marine disaster remote sensing application
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Influence of fault slip on mining-induced pressure and optimization ofroadway support design in fault-influenced zone 被引量:13
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作者 Hongwei Wang Yaodong Jiang +4 位作者 Sheng Xue Lingtao Mao Zhinan Lin Daixin Deng Dengqiang Zhang 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2016年第5期660-671,共12页
This paper presents an investigation on the characteristics of overlying strata collapse and mining-induced pressure in fault-influenced zone by employing the physical modeling in consideration of fault structure. The... This paper presents an investigation on the characteristics of overlying strata collapse and mining-induced pressure in fault-influenced zone by employing the physical modeling in consideration of fault structure. The precursory information of fault slip during the underground mining activities is studied as well. Based on the physical modeling, the optimization of roadway support design and the field verification in fault-influenced zone are conducted. Physical modeling results show that, due to the combined effect of mining activities and fault slip, the mining-induced pressure and the extent of damaged rock masses in the fault-influenced zone are greater than those in the uninfluenced zone. The sharp increase and the succeeding stabilization of stress or steady increase in displacement can be identified as the precursory information of fault slip. Considering the larger mining-induced pressure in the fault-influenced zone, the new support design utilizing cables is proposed. The optimization of roadway support design suggests that the cables can be anchored in the stable surrounding rocks and can effectively mobilize the load bearing capacity of the stable surrounding rocks. The field observation indicates that the roadway is in good condition with the optimized roadway support design. 展开更多
关键词 Physical modeling Fault slipMining-induced pressure Roadway support design field observation
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Calculation of photosynthetically available radiation using multispectral data in the Arctic 被引量:1
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作者 赵进平 王维波 Cooper Lee 《Chinese Journal of Polar Science》 2010年第2期113-126,共14页
Photosynthetically Available Radiation(PAR) is an important bio-optical parameter related to marine primary production.PAR is usually measured by a broadband sensor and can also be calculated by multispectral data.W... Photosynthetically Available Radiation(PAR) is an important bio-optical parameter related to marine primary production.PAR is usually measured by a broadband sensor and can also be calculated by multispectral data.When the PAR is calculated by multispectral data in polar region,four factors are possible error sources.PAR could be overestimated as the wavelengths of multispectral instrument are usually chosen to evade main absorption zones of atmosphere. However,both PARs calculated by hyperspectral and multispectral data are consistent with an error less than 1%.By the fitting function proposed here,the PAR calculated by multispectral data could attain the same accuracy with that by hyperspectral data.To calculate the attenuation rate of the PAR needs PAR_0, the PAR just under the surface.Here,an approach is proposed to calculate PAR_0 by the best fit of the irradiance profile of 1-5 m with a content attenuation coefficient under surface.It is demonstrated by theory and observed data in different time at same location that the attenuation coefficient of PAR is independent of the intensity of radiation.But under sea ice,the attenuation coefficient of PAR is a little bit different,as the spectrum of the light has been changed by selective absorption by the sea ice.Therefore,the difference of inclusions inside the sea ice will result in different PAR,and impact on the attenuation of PAR.By the results of this paper,PAR can be calculated reliably by multispectral data. 展开更多
关键词 PAR marine optics field observation MULTISPECTRAL solar radiation
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Effects of site conditions on earthquake ground motion and their applications in seismic design in loess region 被引量:8
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作者 WANG Lan-min WU Zhi-jian XIA Kun 《Journal of Mountain Science》 SCIE CSCD 2017年第6期1185-1193,共9页
The Loess Plateau is an earthquake prone region of China, where the effects of loess deposit on ground motion were discovered during the 2008 Wenchuan earthquake(Ms8.0) and the 2013 Minxian-Zhangxian earthquake(Ms6.6)... The Loess Plateau is an earthquake prone region of China, where the effects of loess deposit on ground motion were discovered during the 2008 Wenchuan earthquake(Ms8.0) and the 2013 Minxian-Zhangxian earthquake(Ms6.6). The field investigations, observations, and analyses indicated that large number of casualties and tremendous economic losses were caused not only by collapse and damage of houses with poor seismic performance, landslides, but also amplification effects of site conditions, topography and thickness of loess deposit, on ground motion. In this paper, we chose Dazhai Village and Majiagou Village as the typical loess site affected by the two earthquakes for intensity evaluation, borehole exploration, temporary strong motion array, micro tremor survey, and numerical analysis. The aim is to explore the relations between amplification factors and site conditions in terms of topography and thickness of loess deposit. We also developed site amplification factors of ground motion for engineering design consideration at loess sites. The results showed that the amplification effects are more predominant with increase in thickness of loess deposit and slope height. The amplification mayincrease seismic intensity by 1 degree, PGA and predominant period by 2 times, respectively. 展开更多
关键词 Loessial site field investigation Ground motion observation Micro tremor observation Loess topography Loess thickness Site effects Seismic design
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Field observation of total dissolved gas supersaturation of high-dams 被引量:17
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作者 QU Lu LI Ran +2 位作者 LI Jia LI KeFeng DENG Yun 《Science China(Technological Sciences)》 SCIE EI CAS 2011年第1期156-162,共7页
One of the possible negative environmental effects of hydropower stations is the supersaturation of total dissolved gas (TDG) downstream of high-dams,which can lead to gas bubble disease or even death of fish. By taki... One of the possible negative environmental effects of hydropower stations is the supersaturation of total dissolved gas (TDG) downstream of high-dams,which can lead to gas bubble disease or even death of fish. By taking the TDG as the main study object,the paper launched the TDG field observations on Zipingpu,Three Gorges,Ertan,Manwan,Dachaoshan,Gongzui and Ertan dams in China. The factors affecting TDG generation and dissipation were explored. Energy dissipation structures,spill rates and operation patterns were the main factors causing TDG supersaturation. TDG saturations are essentially the same in the hydro-electric tail water and in the upper reaches,so hydro-electric tail water can be less TDG supersaturated through mixing downstream. The main factors affecting the dissipation process of the supersaturated TDG were tributary convergence,water depth and turbulence. TDG supersaturation was unevenly distributed in both the vertical and transverse directions. This study is important because it adds to the accumulating experience of TDG field observations of dam projects in China,and because it objectively and impartially evaluates the impacts of supersaturated TDG. The study also provides field data and references for future studies of TDG supersaturation caused by high-dams. 展开更多
关键词 high-dam total dissolved gas SUPERSATURATION field observation
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A Review of Advances in Lightning Observations during the Past Decade in Guangdong, China 被引量:8
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作者 ZHANG Yijun LU Weitao +7 位作者 CHEN Shaodong ZHENG Dong ZHANG Yang YAN Xu CHEN Liiwen DONG Wansheng DAN Jianru PAN Hanbo 《Journal of Meteorological Research》 SCIE CSCD 2016年第5期800-819,共20页
This paper reviews recent advances in understanding the physical processes of artificially triggered light- ning and natural lightning as well as the progress in testing lightning protection technologies, based on a s... This paper reviews recent advances in understanding the physical processes of artificially triggered light- ning and natural lightning as well as the progress in testing lightning protection technologies, based on a series of lightning field campaigns jointly conducted by the Chinese Academy of Meteorological Sciences and Guangdong Meteorological Bureau since 2006. During the decade-long series of lightning field experi- ments, the technology of rocket-wire artificially triggered lightning has been improved, and has successfully triggered 94 lightning flashes. Through direct lightning current waveform measurements, an average return stroke peak current of 16 kA was obtained. The phenomenon that the downward leader connects to the lateral surface of the upward leader in the attachment process was discovered, and the speed of the upward leader during the connection process being significantly greater than that of the downward leader was re- vealed. The characteristics of several return strokes in cloud-to-ground lighting have also been unveiled, and the mechanism causing damage to lightning protection devices (i.e., ground potential rise within the rated current) was established. The performance of three lightning monitoring systems in Guangdong Province has also been quantitatively assessed. 展开更多
关键词 LIGHTNING field observation experiment artificially triggered lightning lightning physical pro- cesses lightning protection
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