期刊文献+
共找到1,146篇文章
< 1 2 58 >
每页显示 20 50 100
Available parking space occupancy change characteristics and short-term forecasting model 被引量:5
1
作者 季彦婕 王炜 邓卫 《Journal of Southeast University(English Edition)》 EI CAS 2007年第4期604-608,共5页
Based on an available parking space occupancy (APSO) survey conducted in Nanjing, China, an APSO forecasting model is proposed. The APSO survey results indicate that the time series of APSO with different time-secti... Based on an available parking space occupancy (APSO) survey conducted in Nanjing, China, an APSO forecasting model is proposed. The APSO survey results indicate that the time series of APSO with different time-sections are periodical and self-similar, and the fluctuation of the APSO increases with the decrease in time-sections. Taking the short-time change behavior into account, an APSO forecasting model combined wavelet analysis and a weighted Markov chain is presented. In this model, an original APSO time series is first decomposed by wavelet analysis, and the results include low frequency signals representing the basic trends of APSO and several high frequency signals representing disturbances of the APSO. Then different Markov models are used to forecast the changes of low and high frequency signals, respectively. Finally, integrating the predicted results induces the final forecasted APSO. A case study verifies the applicability of the proposed model. The comparisons between measured and forecasted results show that the model is a competent model and its accuracy relies on real-time update of the APSO database. 展开更多
关键词 available parking space occupancy change characteristics short-term forecasting wavelet analysis weighted Markov chain
下载PDF
Climatological Characteristics of the Moisture Budget and Their Anomalies over the Joining Area of Asia and the Indian-Pacific Ocean 被引量:5
2
作者 柳艳菊 丁一汇 +1 位作者 宋亚芳 张锦 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2009年第4期642-655,共14页
The climatological characteristics of the moisture budget over the joining area of Asia and the IndianPacific Ocean (AIPO) and its adjacent regions as well as their anomalies have been estimated in this study. The m... The climatological characteristics of the moisture budget over the joining area of Asia and the IndianPacific Ocean (AIPO) and its adjacent regions as well as their anomalies have been estimated in this study. The main results are as follows. In the winter, the northeasterly moisture transport covers the extensive areas at the lower latitudes of the AIPO. The westerly and northerly moisture transport is the major source and the South Indian Ocean (SIO) is the moisture sink. In the summer, influenced by the southwesterly monsoonal wind, the crossequatorial southwesterly moisture transport across Somali originating from the SIO is transported through the Arabian Sea (AS), the Bay of Bengal (BOB), and the South China Sea (SCS) to eastern China. The AIPO is controlled by the southwesterly moisture transport. The net moisture influx over the AIPO has obvious interannual and interdecadal variations. From the mid- or late 1970s, the influxes over the SIO, the AS, the northern part of the western North Pacific (NWNP), and North China (NC) as well as South China (SC) begin to decrease abruptly, while those over Northeast China (NEC) and the Yangtze River-Huaihe River basins (YHRB) have increased remarkably. As a whole, the net moisture influxes over the BOB and the southern part of the western North Pacific (SWNP) in the recent 50 years take on a linear increasing trend. However, the transition timing for these two regions is different with the former being at the mid- or late 1980s and the latter occurring earlier, approximately at the early stage of the 1970s. The anomalous moisture source associated with the precipitation anomalies is different from the normal conditions of the summer precipitation. For the drought or flood years or the years of E1 Nifio and its following years, the anomalous moisture transport originating from the western North Pacific (WNP) is the vital source of the anomalous precipitation over eastern China, which is greatly related with the variation of the subtropical Pacific high. 展开更多
关键词 the joining area of Asia and the Indian-Pacific Ocean moisture transport and budget climatological characteristics ANOMALIES
下载PDF
CHARACTERISTICS OF ZONAL ANOMALY OF ANNUAL PRECIPITATION IN THE NORTHEASTERN CHINA 被引量:2
3
作者 YANMin-hua DENGWei +1 位作者 CHENPan-qin LIANGLi-qiao 《Chinese Geographical Science》 SCIE CSCD 2004年第4期320-325,共6页
The characteristics of zonal anomaly and change rule of temporal distribution of annual precipitation in the northeastern China are revealed in this paper with EOF (Empirical Orthogonal Function) and REOF (Rotated Emp... The characteristics of zonal anomaly and change rule of temporal distribution of annual precipitation in the northeastern China are revealed in this paper with EOF (Empirical Orthogonal Function) and REOF (Rotated Empirical Orthogonal Function) methods and results are drawn in the standard relief maps with GIS technology for practical application. Data used in the study were obtained from 208 meteorological stations over the northeastern China from 1961 to 2001. EOF results show that the first 3 loading vectors could give entire spatial anomaly structure of annual precipitation. In the Northeast Plain including the Songneng Plain and the Liaohe Plain, there is a regional compatibility (whether wet or dry) of annual precipitation change and this precipitation pattern has occurred since the late 1980s to the present. There also exist annual precipitation patterns of wet (or dry) in south and dry (or wet) in north and wet (or dry) in east and dry (or wet) in west. REOF results display 8 principal precipitation anomaly areas by the first 8 rotated loading vectors: the west plain, the Liaodong hills, the Sanjiang Plain, the Liaoxi hills, the Changbai Mountains, the Hulun Buir Plateau, the southwest plateau and the Liaodong Peninsula. 展开更多
关键词 annual precipitation northeastern China zonal anomaly precipitation characteristics
下载PDF
Device Anomaly Detection Algorithm Based on Enhanced Long Short-Term Memory Network
4
作者 罗辛 陈静 +1 位作者 袁德鑫 杨涛 《Journal of Donghua University(English Edition)》 CAS 2023年第5期548-559,共12页
The problems in equipment fault detection include data dimension explosion,computational complexity,low detection accuracy,etc.To solve these problems,a device anomaly detection algorithm based on enhanced long short-... The problems in equipment fault detection include data dimension explosion,computational complexity,low detection accuracy,etc.To solve these problems,a device anomaly detection algorithm based on enhanced long short-term memory(LSTM)is proposed.The algorithm first reduces the dimensionality of the device sensor data by principal component analysis(PCA),extracts the strongly correlated variable data among the multidimensional sensor data with the lowest possible information loss,and then uses the enhanced stacked LSTM to predict the extracted temporal data,thus improving the accuracy of anomaly detection.To improve the efficiency of the anomaly detection,a genetic algorithm(GA)is used to adjust the magnitude of the enhancements made by the LSTM model.The validation of the actual data from the pumps shows that the algorithm has significantly improved the recall rate and the detection speed of device anomaly detection,with the recall rate of 97.07%,which indicates that the algorithm is effective and efficient for device anomaly detection in the actual production environment. 展开更多
关键词 anomaly detection production equipment genetic algorithm(GA) long short-term memory(LSTM) principal component analysis(PCA)
下载PDF
Research on the Extraction of OLR Anomaly Prior to Ms 7.5 Sand Point,Alaska Earthquake based on IPI Method
5
作者 FENG Maoning ZHANG Yongxian +3 位作者 XIONG Pan LIU Yue TIAN Weixi JU Changhui 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2024年第S01期24-26,共3页
Based on the understanding that the seismic fault system is a nonlinear complex system,Rundle(1995)introduced the nonlinear threshold system used in meteorology to analyze the ocean-atmosphere interface and the El Ni?... Based on the understanding that the seismic fault system is a nonlinear complex system,Rundle(1995)introduced the nonlinear threshold system used in meteorology to analyze the ocean-atmosphere interface and the El Ni?o Southern Oscillation into the study of seismic activity changes,and then proposed the PI method(Rundle et al.,2000a,b).Wu et al.(2011)modified the Pattern Informatics Method named MPI to extract the ionospheric anomaly by using data from DEMETER satellites which is suitable for 1–3 months short-term prediction. 展开更多
关键词 IPI method OLR anomaly prior to earthquake characteristics of OLR anomalies prior to earthquake Quartile method NOAA satellite data
下载PDF
Analysis on Climatic Characteristics of the Precipitation Anomaly in Southwest China in Recent 60 Years
6
作者 ZHANG Rong PANG Jing QIN Jun 《Meteorological and Environmental Research》 CAS 2012年第12期29-32,共4页
[Objective] The research aimed to analyze temporal-spatial distribution characteristics of the precipitation anomaly in southwest China from 1951 to 2010. [Method] Based on monthly precipitation data at 44 stations of... [Objective] The research aimed to analyze temporal-spatial distribution characteristics of the precipitation anomaly in southwest China from 1951 to 2010. [Method] Based on monthly precipitation data at 44 stations of southwest China and 160 stations of China from 1951 to 2010, by using EOF analysis, wavelet analysis and composite analysis, monthly and seasonal change rules of the precipitation in southwest China were analyzed. Corresponding spatial-temporal distribution characteristics of the precipitation in drought and flood years were studied. Temporal-spatial distribution characteristics of the precipitation anomaly in southwest China in recent 60 years were revealed. [Result] Seasonal distribution of the precipitation in southwest China was uneven and was typical single-peak type. Precipitation concentrated from May to September, and peak appeared in July. In recent years, rainfall in autumn significantly became less, while that in other seasons had no obvious change. Precipitation in summer had the cycle of 14 years, another for 6 years and 3-4 years of periodic oscillations. In wet years, precipitation in southwest China had same phase with that in southern China, and anti-phase with that in the junction of Qinghai, Gansu, Xinjiang and Tibet. In dry years, precipitation in southwest China had same phase with that in the eastern part of northwest China and northern China. [Conclusion] The research provided reference basis for prediction and pre-warning of the precipitation in the zone. 展开更多
关键词 Southwest China Precipitation anomaly Climate characteristics China
下载PDF
Analysis on the Characteristics of the Kalpin Ms5.3 Earthquake Sequence of December 1,2013 and Anomalies before the Earthquake
7
作者 Liu Jiaruning Wang Qiong +4 位作者 Nie Xiaohong Gao Ge Zhang Linlin Zhang Zhiguang Xiang Yang 《Earthquake Research in China》 CSCD 2017年第3期381-394,共14页
This paper introduces the basic parameters,focal mechanism solutions and earthquake sequence characteristics of the Kalpin M_S5.3 earthquake sequence of December 1,2013,and analyzed seismic activity before the earthqu... This paper introduces the basic parameters,focal mechanism solutions and earthquake sequence characteristics of the Kalpin M_S5.3 earthquake sequence of December 1,2013,and analyzed seismic activity before the earthquake,the adjacent tectonic features and the precursory anomaly at fixed points within a range of 200 km. Research indicates:(1) The earthquake occurred on Kalpin fault,the source rupture type is thrust faulting with sinistral strike-slip component.( 2) The earthquake sequence is mainshock-aftershock type,with the aftershock distribution attenuating quickly and trending NE.(3) Abnormal seismic activity before the earthquake was characterized by seismically nesting quiescence of MS2. 0-4. 0 earthquakes,seismic quiescence of MS4. 0 earthquakes and seismic belts of MS3. 0 earthquakes in the Kalpin block, abnormal enhancement zone of moderate earthquakes on Puchang fault and seismological parameters.(4) Anomalies of precursory observation data at fixed stations are mainly characterized by mutation. Apart from the borehole tiltmeter in Halajun, the spatial distribution of other abnormal precursors showed a phenomenon of migration from the near field to far field and from the epicenter to the peripheries. 展开更多
关键词 The Kalpin EARTHQUAKE with Ms5.3 Sequence features Seismic activity characteristicS FIXED-POINT precursor observation anomaly
下载PDF
Characteristic Analysis of Anomalies of Strong Earthquakes along the Tancheng-Lujiang Fault Zone and Both Its Sides
8
作者 Li Jianyong Li Jie +3 位作者 Zhang Rui Li Yu Han Yufei Wang Tan 《Earthquake Research in China》 CSCD 2015年第4期498-513,共16页
This article made a systematic statistical analysis on the duration,spatial distribution,form,range,type and reliability of precursory anomalies based on the observations of precursors of 24 moderate-strong earthquake... This article made a systematic statistical analysis on the duration,spatial distribution,form,range,type and reliability of precursory anomalies based on the observations of precursors of 24 moderate-strong earthquakes occurring along the Tancheng-Lujiang fault zone and its bilateral areas in Shandong,Liaoning,Hebei,Jiangsu and Jiangxi Provinces in the period from 1966 to 2005. Results show that:( 1) For M7. 0 and M6. 0earthquakes,med-term abnormities are the greatest in number,short-term abnormities come second,and imminent anomalies are the least. For M5. 0 earthquakes,short-term abnormities are often the most in number,imminent anomalies come second,and the med-term ones are the least.( 2) Precursory anomalies are periodical,part of the med and short-term anomalies are shown as short-term and imminent anomalies during their development.( 3) The development of precursor shows quasi-synchronism; the closer to earthquake occurrence time,the more turning changes of anomalies will appear.( 4)Anomalies mainly occur within an epicenter distance of 100 km, showing a relative concentrated distribution in space,and the shorter the distance to epicenter,the higher the anomaly station / item rate.( 5) The spatial distribution of anomalies is relatively correlated to the strike of structures,having a good consistency with the structure.( 6)There is no significant correlation between duration of abnormities and the epicenter distance.( 7) The higher the magnitude of the earthquake,the greater the amplitude of the abnormities measured with the same observation approach.( 8) In terms of the itemsof the observations,fluid abnormities are the greatest in number,followed by deformation and electromagnetism observations.( 9) For all observation items,med and short-term abnormities make up the majority and short-term and imminent anomalies the minority.( 10) In fluid,deformation and electromagnetism observations,fairly reliable anomalies are about double the number of reliable anomalies. 展开更多
关键词 Tancheng-Lujiang fault zone characteristics of precursory anomaly Fluid anomaly Deformation anomaly Electromagnetic anomaly
下载PDF
Study on Typical Characteristics of Short-Term Precursors in Underground Fluid
9
作者 Liu Yaowei Cao Lingling Ping Jianjun 《Earthquake Research in China》 2005年第2期170-180,共11页
The underground fluid short-term anomalies of earthquake activity are studied. Two kinds of typical characteristics of precursors, the turn-around type and the single type, are summarized. Through studying regional ch... The underground fluid short-term anomalies of earthquake activity are studied. Two kinds of typical characteristics of precursors, the turn-around type and the single type, are summarized. Through studying regional characteristics of earthquake precursors in North China (including Northwest China) and Southwest China, we find that the two types of precursors are strongly related to geological structures in regional distribution and they show varying characteristics with earthquake magnitude in number. 展开更多
关键词 Underground fluid short-term precursor Typical characteristics
下载PDF
Characteristics of Far-field Precursory Anomalies Before the M_S8.1 Earthquake in the West of Kunlun Mountains Pass
10
作者 Chen Yuhua Dong Zhiping +1 位作者 Wang Peiling Li Yongqiang 《Earthquake Research in China》 2009年第3期354-371,共18页
In this study, a number of typical precursory anomalies recorded by stations in Qinghai, Gansu, Sichuan, Xinjiang, Ningxia, Hebei and Shaanxi provinces and autonomous regions before the Ms8.1 earthquake in the west of... In this study, a number of typical precursory anomalies recorded by stations in Qinghai, Gansu, Sichuan, Xinjiang, Ningxia, Hebei and Shaanxi provinces and autonomous regions before the Ms8.1 earthquake in the west of Kunlun Mountains Pass are collected and checked. According to the standards of earthquake cases in China, the criteria of the precursory anomalies are determined, and 53 distinguished. The characteristics of these anomalies before the Ms S. 1 earthquake are analyzed, with results showing a very large earthquake affected area. The precursory anomalies recorded by instruments were 2900 km away from the epicenter, and according to the study in this paper, reached 2100 km away. The results also show that the anomalies present characteristics of long duration, multi-measurement items and large-amplitude variation. The authors believe that in large earthquake monitoring, attention should be paid to the variation of data over a large area, ranging up to thousands kilometers, with much denser earthquake observation networks. 展开更多
关键词 West of Kunlun Mountains Pass Ms8.1 earthquake Typical precursoryanomalies Analysis of anomaly characteristics
下载PDF
Short-term and imminent geomagnetic anomalies of the Wenchuan M_S8.0 earthquake and exploration on earthquake forecast 被引量:2
11
作者 Wuxing Wang Jianhai Ding +1 位作者 Surong Yu Yongxian Zhang 《Earthquake Science》 CSCD 2009年第2期135-141,共7页
The diurnal variation of the geomagnetic vertical component is exhibited mainly by changes of phase and amplitude before strong earthquakes. Based on data recorded by the network of geomagnetic observatories in China ... The diurnal variation of the geomagnetic vertical component is exhibited mainly by changes of phase and amplitude before strong earthquakes. Based on data recorded by the network of geomagnetic observatories in China for many years, the anomalous features of the appearance time of the minima of diurnal variations (i.e, low-point time) of the geo- magnetic vertical components and the variation of their spatial distribution (i.e, phenomena of low-point displacement) have been studied before the Wenchuan Ms8.0 earthquake. The strong aftershocks after two months' quiescence of M6 aftershocks of the Ms8.0 event were forecasted based on these studies. There are good correlativities between these geomagnetic anoma- lies and occurrences of earthquakes. It has been found that most earthquakes occur near the boundary line of sudden changes of the low-point time and generally within four days before or after the 27th or 41st day counting from the day of the appearance of the anomaly. In addition, the imminent anomalies in diurnal-variation amplitudes near the epicentral areas have also been studied before the Wenchuan earthquake. 展开更多
关键词 geomagnetic low-point displacement diurnal-variation amplitude Wenchuan earthquake short-term and imminent geomagnetic anomaly forecast of strong earthquakes
下载PDF
CHARACTERISTICS AND METALLOGENIC EVOLUTION OF AILAOSHAN GOLD METALLOGENIC BELTS IN YUNNAN, CHINA
12
作者 Fang Weixuan, Hu Ruizhong, Bi Xianwu, Su Wenchao 《地学前缘》 EI CAS CSCD 2000年第S1期404-405,共2页
Observations made in different superlarge\|large gold deposits in Ailaoshan gold metallogenic belts, Yunnan Province, China, on the eastern margin of the Qingzang (Himalayas—Karakoram—Tibet) were investigated. Geote... Observations made in different superlarge\|large gold deposits in Ailaoshan gold metallogenic belts, Yunnan Province, China, on the eastern margin of the Qingzang (Himalayas—Karakoram—Tibet) were investigated. Geotectonically, the study area is situated in the conjoint between the Tethys and Himalayas tectonic domain, characterized by very complex geological structure, with strongly influenced by the Himalayas in late development.1\ Regional geology and gold deposits\;Ailaoshan gold metallogenic belts is localized between Ailaoshan super lithospheric faults and Jiujia—Anding brittle\|ductile shear zone, with NNW\|trending about 250km long. To southward, Zhenyuan supergiant gold deposits, Mojiang large gold deposits, and Daping giant gold deposits hosted in low metamorphic volcanic\|sedimentary rocks (D—C). Ore types include gold\|bearing quartz veins, gold\|bearing altered rocks, and the mixing of the two types. Most of gold orebodies took their positions in the substructures of the brittle\|ductile shear zone. 展开更多
关键词 GOLD deposits Ailaoshan GOLD METALLOGENIC BELTS YUNNAN geoc hemical anomaly mineral assemblages geochemical characteristicS EVOLUTIONS of GOLD mineralization
下载PDF
Current tectonic deformation and seismogenic characteristics along the northeast margin of Qinghai -Xizang block
13
作者 王双绪 江在森 +1 位作者 张希 陈文胜 《Acta Seismologica Sinica(English Edition)》 CSCD 2002年第1期29-38,共10页
Based on the data from repeated precise leveling and across-fault deformation measurements carried out in recent 30 years and the analyzed results from GPS observations made in recent years along the northeastern marg... Based on the data from repeated precise leveling and across-fault deformation measurements carried out in recent 30 years and the analyzed results from GPS observations made in recent years along the northeastern margin of Qinghai-Xizang block, and combined with the geological structures and seismic activities, some characteristics in regional tectonic deformation and strong earthquake development are studied and approached preliminarily. The results show that: a) The space-time distribution of current tectonic deformation in this area is inhomogeneous with relatively intensive tectonic deformation in the vicinity of main boundary faults and weak deformation in the farther areas. The intensity of vertical differential movement and the deformation status vary with time, and the horizontal movement and deformation are characterized by apparent compression and strike-slip. b) The tectonic stress field generated by the NE-trending continuous compressive movement of Qinghai-Xizang block due to the northward press and collision of India plate is the principal stress for the tectonic deformation and earthquake development in this area. The evolution of space-time distribution of tectonic deformation and seismicity is closely related to the block activity and dynamic evolution of regional tectonic stress field. c) The vertical deformation uplift and high-gradient deformation zones and the obvious fault deformation anomaly appeared along the boundaries of tectonic blocks can be considered as the indicators of hindered block motion and intensified tectonic stress field for strong earthquake development. Usually, the above-mentioned phenomena would be followed by the seismicity of M6.0, but the earthquake might not occur in the place with the maximum movement. The zones with the fault deformation anomaly characterized by tendencious accumulation acceleration turning and the surrounding areas might be the positions for accumulation of strain energy and development and occurrence of strong earthquakes. 展开更多
关键词 northeast margin of Qinghai-Xizang block vertical crustal deformation horizontal movement and deformation fault deformation anomaly seismogenic characteristics
下载PDF
POSSIBLE CONTRIBUTION OF A TROPICAL CYCLONE TO SHORT-TERM CLIMATE ANOMALIES IN EAST ASIA VIA SNOW COVER ON THE TIBETAN PLATEAU
14
作者 符巧 梁旭东 +2 位作者 张庆红 王子谦 段安民 《Journal of Tropical Meteorology》 SCIE 2017年第4期462-470,共9页
Snow cover on the Tibetan Plateau(TP) has been shown to be essential for the East Asian summer monsoon.In this paper, we demonstrate that tropical cyclone(TC) 04B(1999) in the northern Indian Ocean, which made landfal... Snow cover on the Tibetan Plateau(TP) has been shown to be essential for the East Asian summer monsoon.In this paper, we demonstrate that tropical cyclone(TC) 04B(1999) in the northern Indian Ocean, which made landfall during the autumn of 1999, may have contributed to climate anomalies over East Asia during the following spring and summer by increasing snow cover on the TP. Observations indicate that snow cover on the TP increased markedly after TC 04B(1999) made landfall in October of 1999. Sensitivity experiments, in which the TC was removed from a numerical model simulation of the initial field, verified that TC 04B(1999) affected the distribution as well as increased the amount of snow on the TP. In addition, the short-term numerical modeling of the climate over the region showed that the positive snow cover anomaly induced negative surface temperature, negative sensible heat flux, positive latent heat flux, and positive soil temperature anomalies over the central and southern TP during the following spring and summer. These climate anomalies over the TP were associated with positive(negative) summer precipitation anomalies over the Yangtze River valley(along the southeastern coast of China). 展开更多
关键词 tropical cyclone snow cover anomaly short-term climate anomalies
下载PDF
The quiescence of earthquakes with M_L≥4.0 as an important precursory characteristic prior to strong shocks in North China region
15
作者 平建军 张青荣 +1 位作者 曹肃朝 边庆凯 《Acta Seismologica Sinica(English Edition)》 CSCD 2001年第4期471-480,共9页
关键词 North China region quiescence anomaly index for short-term prediction
下载PDF
Study of the Evolutionary Characteristics of Precursor Information Fields in North China Region and Their Relation to Earthquakes
16
作者 Ping Jianjun,Luo Lange and Cao SuchaoSeismoiogicaJ Bureau of Hehei Province, Shijiazhuang 050021 , China 《Earthquake Research in China》 2001年第1期36-46,共11页
On the basis of previous study results about the seismic anomaly precursor information quantity, universal and synthetic mathematical expressions that describe the precursor information quantity of various seismic ano... On the basis of previous study results about the seismic anomaly precursor information quantity, universal and synthetic mathematical expressions that describe the precursor information quantity of various seismic anomalies are further given. Starting from large amounts of data of earthquake cases, the problem of the sustained effective time of seismic anomaly was studied again and the mathematical relationship between the sustained effective time of seismic anomaly and continuing effective time of seismic anomaly was further established. About one million pieces of precursor observation data belonging to 371 items of hydrochemistry, deformation, geomagnetism, stress, water level, geoelectricity, etc. In North China region in the period of 1980~ 1997 were collected and sorted out, and the seismic anomaly precursor information quantity of these items was calculated item by item. The evolutionary characteristics of seismic anomaly precursor information field in North China region in about 20 years and their relation to earthquakes were studied; an index system for medium- and short-term predictions of earthquakes with Ms ≥ 5.0 in North China region was established. After having checked by the R-value scoring method, the index system for synthetic earthquake prediction was proved to be of certain efficacy in medium- and short-term earthquake prediction. 展开更多
关键词 Earthquake anomaly Information field Evolutional characteristicS
下载PDF
2023年中国气候异常特征及主要天气气候事件 被引量:1
17
作者 竺夏英 孙林海 +17 位作者 钟海玲 支蓉 艾婉秀 姜允迪 李威 陈鲜艳 邹旭恺 王凌 赵珊珊 曾红玲 王有民 冯爱青 朱晓金 代潭龙 郭艳君 张颖娴 李想 龚振淞 《气象》 CSCD 北大核心 2024年第2期246-256,共11页
2023年,我国气候主要表现为暖干的特征,全国平均气温10.71℃,较1991—2020年气候平均偏高0.82℃,为1951年以来最暖;全国平均降水量615.0 mm,较常年偏少3.9%,为2012年以来第二少。四季气温均较常年同期偏高,其中夏、秋季分别为历史同期... 2023年,我国气候主要表现为暖干的特征,全国平均气温10.71℃,较1991—2020年气候平均偏高0.82℃,为1951年以来最暖;全国平均降水量615.0 mm,较常年偏少3.9%,为2012年以来第二少。四季气温均较常年同期偏高,其中夏、秋季分别为历史同期次高和最高;除秋季降水偏多外,其余三季降水均偏少。汛期(5—9月),全国平均降水量较常年同期偏少4.3%,为2012年以来第二少,我国中东部降水总体呈“中间多南北少”的分布。2023年,我国区域性气象干旱多发,西南地区遭遇冬春连旱;春季北方沙尘天气过程偏多;夏季前期,华北和黄淮遭受1961年以来最强高温过程;7月底至8月初,受台风杜苏芮影响,京津冀地区发生历史罕见极端强降水过程,华北地区出现“旱涝急转”;华西秋雨开始早、结束晚、雨量多;1月中旬发生年内最强寒潮过程;秋末冬初冷空气频繁入侵,12月华北和黄淮等地降雪日数偏多、积雪偏深。 展开更多
关键词 气候异常特征 极端天气气候事件 气象灾害
下载PDF
云南地区氡异常与地震的统计特征分析
18
作者 李琼 付虹 +2 位作者 胡小静 杜家云 杨黎 《地震学报》 CSCD 北大核心 2024年第2期340-352,共13页
通过梳理1976—2022年震例总结报告中云南地区73组M_(S)≥5.0地震的氡测项异常,对其特征予以统计分析。结果表明:73组地震中有63组震前出现水氡异常,震前6个月内的短期异常占总异常的71%,3个月内的短临异常占总异常的49%,地震前3个月异... 通过梳理1976—2022年震例总结报告中云南地区73组M_(S)≥5.0地震的氡测项异常,对其特征予以统计分析。结果表明:73组地震中有63组震前出现水氡异常,震前6个月内的短期异常占总异常的71%,3个月内的短临异常占总异常的49%,地震前3个月异常数量增加显著;震级越大,异常分布越远离震中,震前1个月新出现的异常大部分集中在震中附近。相对而言,由于测点位置和观测技术方面的原因,气氡积累的震例远远少于水氡,但具有短期异常占比较高的优势。随着气氡观测技术的不断改进和观测经验的不断积累,其捕捉地震异常信息的能力也将会不断提升。 展开更多
关键词 地震异常 地震预测 统计特征
下载PDF
山西极端暴雨环流特征及水汽异常研究
19
作者 周晋红 王秀明 +3 位作者 田晓婷 张泽秀 李树文 蔡晓芳 《干旱气象》 2024年第3期426-436,共11页
研究山西极端暴雨发生规律对开展预报预警、灾害防御具有重要意义。本文利用常规观测资料和欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)第五代大气再分析资料(ERA5),采用标准化距平作为异常度,运... 研究山西极端暴雨发生规律对开展预报预警、灾害防御具有重要意义。本文利用常规观测资料和欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)第五代大气再分析资料(ERA5),采用标准化距平作为异常度,运用环流分析和物理量诊断等方法,研究1981—2018年6—9月山西17次极端暴雨的气候特征、环流影响系统和水汽异常特征。结果表明:山西极端暴雨主要出现在7—8月,暴雨区主要位于中南部,2010年以来极端暴雨明显多发;影响系统主要是700 h Pa低涡和台风系统,有偏南和偏东两支水汽通道。极端暴雨过程中,低层水汽含量明显偏高,从暴雨区平均比湿的过程最大值看,大部分过程850 h Pa超过14.2 g·kg^(-1),700 h Pa则可超过9.8 g·kg^(-1)、对应暴雨区平均异常度达1.6以上;水汽的极端性在低层水汽通量辐合中心表现突出,17次极端暴雨700、850 h Pa暴雨区水汽通量辐合中心过程最大值的异常度均值分别达-8、-6,其中台风减弱低压影响下的极端暴雨850 h Pa水汽通量辐合中心最大异常度达-12。根据以上环流和水汽特征建立极端暴雨概念模型,并给出极端暴雨低层水汽含量和水汽通量辐合强度预报参考指标。 展开更多
关键词 极端暴雨 环流特征 水汽异常 预报指标
下载PDF
2018年9月8日墨江5.9级地震云南普洱大寨流体异常特征及机理
20
作者 胡小静 付虹 +4 位作者 张翔 李利波 黄江培 李琼 高文斐 《地震地质》 EI CSCD 北大核心 2024年第2期477-491,共15页
文中梳理了2004年以来普洱大寨井连续观测的水化学离子和井-含水层渗透性异常特征。研究发现,在观测井周边250km范围内5.5级以上地震发生前,多次出现过可重复、可类比的异常变化,对地震具有较好的异常指示和预测意义。但相比以往震例,墨... 文中梳理了2004年以来普洱大寨井连续观测的水化学离子和井-含水层渗透性异常特征。研究发现,在观测井周边250km范围内5.5级以上地震发生前,多次出现过可重复、可类比的异常变化,对地震具有较好的异常指示和预测意义。但相比以往震例,墨江5.9级地震发生前,无论是化学离子还是物理参数均出现了观测以来幅度最大的变化,异常状态较以往强烈很多,但发震的震级只有5.9级。为了研究这一现象产生的原因和机理,文中尝试从区域深部物质活动和区域应力水平2个方面对墨江5.9级地震前的异常演化过程开展讨论,得到以下认识:墨江5.9级地震前,流体异常整体呈现出较为显著的从深部到浅部、从背景到短期微观异常再到临震宏观异常的演化过程;墨江5.9级地震前,普洱大寨连续观测的水化学离子浓度异常和井-含水层渗透性的改变是由于区域内垂向剪切应力持续增强引起的含水层受挤压,从而形成了垂向的流体补给,最终引起不同含水层水体发生交替混合而产生的结果;本次异常形成初期还伴随深部物质剧烈活动的现象,较为显著的由深部到浅部的耦合作用过程可能是导致墨江5.9级地震前出现自观测以来地下流体异常幅度最显著的原因。因此,流体活动从深部开始,随着区域应力不断积累,不断向地表传递的演变过程是墨江5.9级地震前流体异常演化的本质特征;区域应力的作用方式和深部物质活动程度不同,是引起墨江5.9级地震前异常特征与研究区其他历史震例前明显不同的根本原因。文中研究为全面认识普洱大寨井地下流体异常的预测意义和地震前流体异常的深浅耦合演化过程提供了一定参考。 展开更多
关键词 地下流体异常 深浅耦合 普洱大寨井 墨江5.9级地震
下载PDF
上一页 1 2 58 下一页 到第
使用帮助 返回顶部