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11.
Xiushu QIE Shanfeng YUAN Zhixiong CHEN Dongfeng WANG Dongxia LIU Mengyu SUN Zhuling SUN Abhay SRIVASTAVA Hongbo ZHANG Jingyu LU Hui XIAO Yongheng BI Liang FENG Ye TIAN Yan XU Rubin JIANG Mingyuan LIU Xian XIAO Shu DUAN Debin SU Chengyun SUN Wenjing XU Yijun ZHANG Gaopeng LU Da-Lin ZHANG Yan YIN Ye YU 《中国科学:地球科学(英文版)》2021,64(1):10-26
The Dynamical-microphysical-electrical Processes in Severe Thunderstorms and Lightning Hazards(STORM973)project conducted coordinated comprehensive field observations of thunderstorms in the Beijing metropolitan region(BMR)during the warm season from 2014 to 2018.The aim of the project was to understand how dynamical,microphysical and electrical processes interact in severe thunderstorms in the BMR,and how to assimilate lightning data in numerical weather prediction models to improve severe thunderstorm forecasts.The platforms used in the field campaign included the Beijing Lightning Network(BLNET,consisting of 16 stations),2 X-band dual linear polarimetric Doppler radars,and 4 laser raindrop spectrometers.The collaboration also made use of the China Meteorological Administration’s mesoscale meteorological observation network in the Beijing-Tianjin-Hebei region.Although diverse thunderstorm types were documented,it was found that squall lines and multicell storms were the two major categories of severe thunderstorms with frequent lightning activity and extreme rainfall or unexpected local short-duration heavy rainfall resulting in inundations in the central urban area,influenced by the terrain and environmental conditions.The flash density maximums were found in eastern Changping District,central and eastern Shunyi District,and the central urban area of Beijing,suggesting that the urban heat island effect has a crucial role in the intensification of thunderstorms over Beijing.In addition,the flash rate associated with super thunderstorms can reach hundreds of flashes per minute in the central city regions.The super(5%of the total),strong(35%),and weak(60%)thunderstorms contributed about 37%,56%,and 7%to the total flashes in the BMR,respectively.Owing to the close connection between lightning activity and the thermodynamic and microphysical characteristics of the thunderstorms,the lightning flash rate can be used as an indicator of severe weather events,such as hail and short-duration heavy rainfall.Lightning data can also be assimilated into numerical weather prediction models to help improve the forecasting of severe convection and precipitation at the cloud-resolved scale,through adjusting or correcting the thermodynamic and microphysical parameters of the model. 相似文献
12.
P S Dhinwa S K Pathan S V C Sastry Mukund Rao K L Majumder M L Chotani J Premnath Singh R L P Sinha 《Journal of the Indian Society of Remote Sensing》1992,20(4):237-250
Knowledge on area and distribution of land uses plays an important role in district planning. An attempt has been made here to study existing land use pattern and changes in the land use pattern of Bharatpur district. Multi-date remote sensing data (1986 and 1989) has been used for the purpose. Seventeen land use maps on 1∶50,000 scale were prepared. ARC/INFO GIS package has been employed for the land use analysis. GIS package has also been used to relate the land use information to the villages and arrive at tentative comparison of land use as is reported in Census and as obtained from the remote sensing. Major findings in land use pattern of Bharatpur district are a) that the land use pattern in Bharatpur district is not similar to that of general land use pattern prevalent in Rajasthan State as a whole, b) Agriculture is the predominant user of land occupying about 75 percent of the reporting area, c) Forest cover in the district is not very significant and it has been depleted from 5.6 percent to 3.1 percent, d) the area under pastures and tree crops is also negligible and e) Area under waste land (eroded land, undulating terrain with or without scrub and rock out crops has been increased from 6.34 percent to 7.89 percent. The area under salt affected land, sandy area and water logged area has been decreased from 6.83 percent to 2.09 percent. 相似文献
13.
A stochastic critical excitation is defined as that excitation with a given variance that maximizes the variance in the dynamic response of a system. A non-stationary filtered shot noise is used to develop a stochastic critical excitation model of an earthquake ground motion process, and the response statistics for a linear system are determined in both time and frequency domains. The sensitivity of response to several assumed earthquake pulse arrival rate functions is examined. Responses to recorded strong ground motion and to stochastic critical excitations with the same total energy are compared to assess the degree of conservatism in the procedure. An application of the procedure to seismic qualification of equipment is presented. 相似文献
14.
Lightning activity and its relationship with typhoon intensity and vertical wind shear for Super Typhoon Haiyan (1330) 
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下载免费PDF全文 Super Typhoon Haiyan (1330), which occurred in 2013, is the most powerful typhoon during landfall in the meteorological record. In this study, the temporal and spatial distributions of lightning activity of Haiyan were analyzed by using the lightning data from the World Wide Lightning Location Network, typhoon intensity and position data from the China Meteorological Administration, and horizontal wind data from the ECMWF. Three distinct regions were identified in the spatial distribution of daily average lightning density, with the maxima in the inner core and the minima in the inner rainband. The lightning density in the intensifying stage of Haiyan was greater than that in its weakening stage. During the time when the typhoon intensity measured with maximum sustained wind speed was between 32.7 and 41.4 ms?1, the storm had the largest lightning density in the inner core, compared with other intensity stages. In contrast to earlier typhoon studies, the eyewall lightning burst out three times. The first two eyewall lightning outbreaks occurred during the period of rapid intensification and before the maximum intensity of the storm, suggesting that the eyewall lightning activity could be used to identify the change in tropical cyclone intensity. The flashes frequently occurred in the inner core, and in the outer rainbands with the black body temperature below 220 K. Combined with the ECMWF wind data, the influences of vertical wind shear (VWS) on the azimuthal distribution of flashes were also analyzed, showing that strong VWS produced downshear left asymmetry of lightning activity in the inner core and downshear right asymmetry in the rainbands. 相似文献
15.
The present study investigated the chemical composition of wet atmospheric precipitation in India’s richest coal mining belt.
Total 418 samples were collected on event basis at six sites from July to October in 2003 and May to October in 2004 and analysed
for pH, EC, F−, Cl−, , , Ca2+, Mg2+, Na+, K+ and . The average pH value (5.7) of the rainwater of the investigated area is alkaline in nature. However, the temporal pH variation
showed the alkaline nature during the early phase of monsoonal rainfall but it trends towards acidic during the late and high
rainfall periods. The rainwater chemistry of the region showed high contribution of Ca2+ (47%) and (21%) in cations and (55%) and Cl− (23%) in anionic abundance. The high non seas salt fraction (nss) of Ca2+ (99%) and Mg2+ (96%) suggests crustal source of the ions, while the high nss (96%) and high ratio signifying the impact of anthropogenic sources and the source of the acidity. The ratio of varies from 0.03 to 3.23 with the average value of 0.84 suggesting that Ca2+ and play a major role in neutralization processes. The assessment of the wet ionic deposition rates shows no any specific trend,
however Ca2+ deposition rate was highest followed by and
. 相似文献
16.
Abhay Kumar Singh G. C. Mondal P. K. Singh S. Singh T. B. Singh B. K. Tewary 《Environmental Geology》2005,48(8):1014-1028
Water samples collected from the six reservoirs of Damodar River basin in pre- and post-monsoon, have been analysed, to study
the major ion chemistry and the weathering and geochemical processes controlling the water composition. Ca, Na and HCO3 dominate the chemical composition of the reservoir water. The seasonal data shows a minimum concentration of most of the
ions in post-monsoon and a maximum concentration in pre-monsoon seasons, reflecting the concentrating effects due to elevated
temperature and increased evaporation during the low water level period of the pre-monsoon season. Water chemistry of the
reservoirs strongly reflects the dominance of continental weathering aided by atmospheric and anthropogenic activities in
the catchment area. Higher concentration of SO4 and TDS in Panchet, Durgapur and Tenughat reservoirs indicate mining and anthropogenic impact on water quality. The high
contribution of (Ca+Mg) to the total cations, high concentration of dissolved silica, relatively high (Na+K)/TZ+ ratio (0.3) and low equivalent ratio of (Ca+Mg)/(Na+K) suggests combined influence of carbonate and silicate weathering.
Kaolinite is the possible mineral that is in equilibrium with the water, implying that the chemistry of reservoir water favours
kaolinite formation. The calculated values of SAR, RSC and sodium percentage indicate the ‘excellent to good quality’ of water
for irrigation uses. 相似文献
17.
北京地区的闪电时空分布特征及不同强度雷暴的贡献 总被引：2，自引：2，他引：0
利用北京闪电定位网(BLNET,Beijing Lightning Network)和SAFIR3000(Surveillance et Alerte Foudre par Interometrie Radioelectrique)定位网7年共423次雷暴的闪电资料,并按照雷暴产生闪电多少,同时参考雷达回波和雷暴持续时间,将雷暴划分为弱雷暴(≤1000次)、强雷暴(>1000次且≤10000次)和超强雷暴(>10000次),分析了北京地区的闪电时空分布特征及不同强度等级雷暴对闪电分布的贡献。北京总闪电密度最大值约为15.4 flashes km-2a(^-1),平均值约为1.9 flashes km^-2a(^-1),大于8 flashes km^-2a(^-1)的闪电密度高值区基本分布在海拔高度200 m等高线以下的平原地带。不同强度雷暴对总雷暴闪电总量贡献不同,弱雷暴(超强雷暴)次数多(少),产生的闪电少(多),超强雷暴和强雷暴产生的闪电分别占总雷暴闪电的37%和56%。不同强度雷暴对总雷暴的闪电密度高值中心分布和闪电日变化特征影响显著,昌平区东部、顺义区中东部和北京主城区是总雷暴闪电密度大于12 flashes km-2a(-1)的三个主要高值区中心,前两个高值中心受强雷暴影响大,而主城区高值中心主要受超强雷暴影响。总雷暴晚上频繁的闪电活动主要受超强雷暴和强雷暴影响,这两类雷暴晚上闪电活动活跃,分别占各自总闪电的69%和65%,而弱雷暴闪电活动白天陡增很快,对总雷暴午后的闪电活动影响大。另外,不同下垫面条件闪电日变化差异大,山区最强的闪电活动出现在白天,午后闪电活动增强很快,主峰值出现在北京时间18:00,而平原最强的闪电活动发生在晚上,平原(山麓)的主峰值比山区推迟了约1.5小时(1小时)。 相似文献
18.
Abhay M. Varade Y. D. Khare Poonam Yadav A. P. Doad Sandipan Das Madhura Kanetkar R. B. Golekar 《Journal of the Indian Society of Remote Sensing》2018,46(4):539-549
Hard rock aquifer system, as it lacks in primary porosity, is complex because of heterogeneity, and hence its performance solely depends on secondary factors such as weathering, fractures, joints and lineaments, etc. As a result, there is no uniformity in behavior of such aquifer system which varies with the intensity of factors causing secondary porosity. In view of this aquifer system of hard rock, particularly multilayered aquifer system such as basalt, the targeting of deeper aquifer system becomes uncertain. Under this situation, mapping of lineament assumes great importance particularly for targeting the deeper aquifer. In view of this, a small watershed WGKKC-2 falling in Nagpur District of Central India has been studied in detail to understand the significance of lineaments on governing deeper aquifer system. The study has been carried out by deploying remote sensing technique for delineation of hydro geomorphology and lineaments vis-à-vis performance of bore wells. The results are encouraging which mainly emphasize the role of lineament mapping in hard rock aquifer system for identification of groundwater potential zones. 相似文献
19.
R. H. Sawkar Mukund Joshi M. H. Swaminath G. Guruprasad 《Journal of the Geological Society of India》2018,92(4):389-392
85% of water resources is used in agriculture. Price of water is not taken into account while declaring the Minimum Support Price (MSP) for different crops by Government of India (GoI). Origin of water, depletion of groundwater table and its effect on sea level changes and climate are discussed with reference to geomorphology of Sahyadri hill range, where both east and west flowing rivers of peninsular India take their origin. New price based on incentive to be given to farmers who take up growing crops using less water compared to rice and sugarcane is suggested. 相似文献
20.
The fluvial geochemistry of the Subarnarekha River and its major tributaries has been studied on a seasonal basis in order to assess the geochemical processes that explain the water composition and estimate solute fluxes. The analytical results show the mildly acidic to alkaline nature of the Subarnarekha River water and the dominance of \(\hbox {Ca}^{2+}\) and \(\hbox {Na}^{+}\) in cationic and \(\hbox {HCO}_{3}^{-}\) and \({\hbox {Cl}}^{-}\) in anionic composition. Minimum ionic concentration during the monsoon and maximum concentration in the pre-monsoon seasons reflect concentrating effects due to decrease in the river discharge and increase in the base flow contribution during the pre-monsoon and dilution effects of atmospheric precipitation in the monsoon season. The solute acquisition processes are mainly controlled by weathering of rocks, with minor contribution from marine and anthropogenic sources. Higher contribution of alkaline earth \((\hbox {Ca}^{2+}{+}\,\hbox {Mg}^{2+})\) to the total cations \((\hbox {TZ}^{+})\) and high \((\hbox {Na}^{+}+\hbox {K}^{+})/\hbox {Cl}^{-}\), \((\hbox {Na}^{+}+\hbox {K}^{+})/\hbox {TZ}^{+}\), \(\hbox {HCO}_{3}^{-}/(\hbox {SO}_{4}^{2-}+\hbox {Cl}^{-})\) and low \((\hbox {Ca}^{2+}+\hbox {Mg}^{2+})/(\hbox {Na}^{+}+\hbox {K}^{+})\) equivalent ratios suggest that the Subarnarekha River water is under the combined influence of carbonate and silicate weathering. The river water is undersaturated with respect to dolomite and calcite during the post-monsoon and monsoon seasons and oversaturated in the pre-monsoon season. The pH–log \(\hbox {H}_{4}\hbox {SiO}_{4}\) stability diagram demonstrates that the water chemistry is in equilibrium with the kaolinite. The Subarnarekha River annually delivered \(1.477\times 10^{6}\) ton of dissolved loads to the Bay of Bengal, with an estimated chemical denudation rate of \(77\hbox { ton km}^{-2}\hbox { yr}^{-1}\). Sodium adsorption ratio, residual sodium carbonate and per cent sodium values placed the studied river water in the ‘excellent to good quality’ category and it can be safely used for irrigation. 相似文献