Based on the daily rainfall data from China Meteorological Administration,the tropical cyclone（TC） best track data from Japan Meteorological Agency,and the NCEP-NCAR reanalysis data from NOAA,regional mean daily pre...Based on the daily rainfall data from China Meteorological Administration,the tropical cyclone（TC） best track data from Japan Meteorological Agency,and the NCEP-NCAR reanalysis data from NOAA,regional mean daily precipitation extreme（RDPE） events over southeastern China（specifically,the Fujian-Jiangxi region（FJR）） and the associated circulation anomalies are investigated.For the summers of 1979-2011,a total of 105 RDPE events are identified,among which 35 are TC-infiuenced（TCIn-RDPE） and 70 are TCfree events（TCFr-RDPE）.Distinct differences between these two types of RDPEs are found in both their statistical features and the related circulation patterns.TCFr-RDPEs usually occur in June,while TCInRDPEs mainly take place during July-August.When TCFr-RDPEs happen,a center of the anomalous cyclonic circulation is observed over the FJR,with an anomalous anticyclonic circulation to the south of this region.The warm/moist air flows from the South China Sea（SCS） and western Pacific meet with colder air from the north,forming a narrow convergent belt of water vapor over the FJR.Simultaneously,positive diabatic forcing anomalies are observed over the FJR,whereas negative anomalies appear over both its south and north sides,facilitating the formation and maintenance of the cyclonic circulation anomaly,as well as the upward motion of the atmosphere,over the FJR.When TCIn-RDPEs occur,southeastern China is dominated by a TC-related stronger anomalous cyclonic circulation.An anomalous anticyclonic circulation in the mid and high latitudes north of the FJR exists in the mid and upper troposphere,opposite to the situation during TCFr-RDPE events.Abundant warm/wet air is carried into the FJR from both the Indian Ocean and the SCS,leading to a large amount of latent heat release over the FJR and inducing strong ascending motion there.Furthermore,large differences are also found in the manifestation of Rossby wave energy propagation between these two types of RDPE events.The results of this study are helpf展开更多
It is believed that the microseismicity induced by mining effect and gas gradient disturbance stress is a precursor to the essential characteristics of roadway unstability. In order to effectively identify and evaluat...It is believed that the microseismicity induced by mining effect and gas gradient disturbance stress is a precursor to the essential characteristics of roadway unstability. In order to effectively identify and evaluate the stability of coal roadways in the process of mine development and extraction, a microseismic monitoring system was deployed for the study of the stress evolution process, damage degree and distribution characteristics in the tailgate and headgate. The mine under study is the 62113 outburst working face of Xin Zhuangzi coalmine in Huainan mining area. The whole process of microfractures initiation,extension, interaction and coalescence mechanisms during the progressive failure processes of the coal rock within the delineated and typical event clusters were investigated by means of a two dimensional realistic failure process analysis code(RFPA2D-Flow). The results show that the microseismic events gradually create different-sized event clusters. The microseismicity of the tailgate is significantly higher than that of the headgate. The study indicates that the greater anomalous stress region matches the area where microfractures continuously develop and finally connect to each other and form a fissure zone.Due to the mine layout and stress concentration, the ruptured area is mainly located on the left shoulder of the tailgate roof. The potential anomalous stress region of the coal roadway obtained by numerical simulation is relatively in good agreement with the trend of spatial macro evolution of coal rock microfractures captured by the microseismic monitoring system. The research results can provide important basis for understanding instability failure mechanism of deep roadway and microseismic activity law in complex geologic conditions, and it ultimately can be used to guide the selection and optimization of reinforcement and protection scheme.展开更多
By using the precursory anomalies at fixed seismological stations or observational points in China, which are obtained every year from the Assembly of National Seismologic Consideration (ANSC) from 1988 to 1996, to st...By using the precursory anomalies at fixed seismological stations or observational points in China, which are obtained every year from the Assembly of National Seismologic Consideration (ANSC) from 1988 to 1996, to study the relationship between the anomalies in a certain year and the earthquakes occurring in the Chinese mainland in the next year. Based on the anomalies before 84 moderate or large earthquakes, it is concluded that except for the means of ground water level, the anomalous ratios for the other six means of earthquake forecasting in seismic regions are smaller than that in aseismic regions or that in the whole mainland of China. The means which has the maximum anomalous ratio is the means of ground water level, and the regions where the maximum ratio is observed are Xinjiang Uygur Autonomous Region, Sichuan and Yunnan provinces. The means which have the second anomalous ratios are the hydrogeochemistry and deformation and the regions where the second ratio is obtained are Xinjiang Uygur Autonomous Region, Yunnan Province. The means which has the minimum ratio is geomagnetism, the regions where the minimum ratio is observed are Inner Mongolia Autonomous Region and South China. The composite nomalous ratios for all means are 26.85% in seismic regions, 25.11% in aseismic regions. The latter also is the background level of precursory anomalies in Chinese Seismological Network. The anomalous ratios are 26.30% for the earthquakes of M S about 5.0 within the range of 200 km distant from the epicenter, 29.19% for earthquakes about 6.0 within 300 km, and 29.44% for earthquakes about 7.0 within 500 km.展开更多
基金Supported by the China Meteorological Administration Special Public Welfare Research Fund Province(GYHY201406024)National Natural Science Foundation of China(41330425)+1 种基金Creative Program of Science&Technology of Jiangsu(KYZZ-0239and CXZZ12_0485)Creative Program of the State Key Laboratory of Severe Weather(2015LASW-A03)
文摘Based on the daily rainfall data from China Meteorological Administration,the tropical cyclone（TC） best track data from Japan Meteorological Agency,and the NCEP-NCAR reanalysis data from NOAA,regional mean daily precipitation extreme（RDPE） events over southeastern China（specifically,the Fujian-Jiangxi region（FJR）） and the associated circulation anomalies are investigated.For the summers of 1979-2011,a total of 105 RDPE events are identified,among which 35 are TC-infiuenced（TCIn-RDPE） and 70 are TCfree events（TCFr-RDPE）.Distinct differences between these two types of RDPEs are found in both their statistical features and the related circulation patterns.TCFr-RDPEs usually occur in June,while TCInRDPEs mainly take place during July-August.When TCFr-RDPEs happen,a center of the anomalous cyclonic circulation is observed over the FJR,with an anomalous anticyclonic circulation to the south of this region.The warm/moist air flows from the South China Sea（SCS） and western Pacific meet with colder air from the north,forming a narrow convergent belt of water vapor over the FJR.Simultaneously,positive diabatic forcing anomalies are observed over the FJR,whereas negative anomalies appear over both its south and north sides,facilitating the formation and maintenance of the cyclonic circulation anomaly,as well as the upward motion of the atmosphere,over the FJR.When TCIn-RDPEs occur,southeastern China is dominated by a TC-related stronger anomalous cyclonic circulation.An anomalous anticyclonic circulation in the mid and high latitudes north of the FJR exists in the mid and upper troposphere,opposite to the situation during TCFr-RDPE events.Abundant warm/wet air is carried into the FJR from both the Indian Ocean and the SCS,leading to a large amount of latent heat release over the FJR and inducing strong ascending motion there.Furthermore,large differences are also found in the manifestation of Rossby wave energy propagation between these two types of RDPE events.The results of this study are helpf
基金Financial support for this work, provided by the National Natural Science Foundation of China (Nos.51674189,51304154,and 51327007)the Youth Science and technology new star of Shaanxi Province (No.2016KJXX-37)the Scientific research plan of Shaanxi Education Department (No.16JK1487)
文摘It is believed that the microseismicity induced by mining effect and gas gradient disturbance stress is a precursor to the essential characteristics of roadway unstability. In order to effectively identify and evaluate the stability of coal roadways in the process of mine development and extraction, a microseismic monitoring system was deployed for the study of the stress evolution process, damage degree and distribution characteristics in the tailgate and headgate. The mine under study is the 62113 outburst working face of Xin Zhuangzi coalmine in Huainan mining area. The whole process of microfractures initiation,extension, interaction and coalescence mechanisms during the progressive failure processes of the coal rock within the delineated and typical event clusters were investigated by means of a two dimensional realistic failure process analysis code(RFPA2D-Flow). The results show that the microseismic events gradually create different-sized event clusters. The microseismicity of the tailgate is significantly higher than that of the headgate. The study indicates that the greater anomalous stress region matches the area where microfractures continuously develop and finally connect to each other and form a fissure zone.Due to the mine layout and stress concentration, the ruptured area is mainly located on the left shoulder of the tailgate roof. The potential anomalous stress region of the coal roadway obtained by numerical simulation is relatively in good agreement with the trend of spatial macro evolution of coal rock microfractures captured by the microseismic monitoring system. The research results can provide important basis for understanding instability failure mechanism of deep roadway and microseismic activity law in complex geologic conditions, and it ultimately can be used to guide the selection and optimization of reinforcement and protection scheme.
文摘By using the precursory anomalies at fixed seismological stations or observational points in China, which are obtained every year from the Assembly of National Seismologic Consideration (ANSC) from 1988 to 1996, to study the relationship between the anomalies in a certain year and the earthquakes occurring in the Chinese mainland in the next year. Based on the anomalies before 84 moderate or large earthquakes, it is concluded that except for the means of ground water level, the anomalous ratios for the other six means of earthquake forecasting in seismic regions are smaller than that in aseismic regions or that in the whole mainland of China. The means which has the maximum anomalous ratio is the means of ground water level, and the regions where the maximum ratio is observed are Xinjiang Uygur Autonomous Region, Sichuan and Yunnan provinces. The means which have the second anomalous ratios are the hydrogeochemistry and deformation and the regions where the second ratio is obtained are Xinjiang Uygur Autonomous Region, Yunnan Province. The means which has the minimum ratio is geomagnetism, the regions where the minimum ratio is observed are Inner Mongolia Autonomous Region and South China. The composite nomalous ratios for all means are 26.85% in seismic regions, 25.11% in aseismic regions. The latter also is the background level of precursory anomalies in Chinese Seismological Network. The anomalous ratios are 26.30% for the earthquakes of M S about 5.0 within the range of 200 km distant from the epicenter, 29.19% for earthquakes about 6.0 within 300 km, and 29.44% for earthquakes about 7.0 within 500 km.
