Academy of Sciences,Beijing 100029 2 Lanzhou University,Lanzhou 730000 3 Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences,Lanzhou 730000 4 Nanjing University of Infor...Academy of Sciences,Beijing 100029 2 Lanzhou University,Lanzhou 730000 3 Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences,Lanzhou 730000 4 Nanjing University of Information Science＆Technology,Nanjing 210044 Using both fast and slow electric field change sensors and field mill,multi-station observations on lightning flashes over China inland plateau areas were conducted during the summer of 2004.All of the stations were synchronized by GPS with a time-resolution of±50 ns.Using the different time of arrival（DTOA）and based on the fast electric field change sensor,a lightning radiation location technique was developed.Radiation pulses in the initial stages of five intracloud（IC）lightning discharges which occurred on 20 August were analyzed.The results indicate that the technique developed could effectively locate the lightning radiation sources.Furthermore,the lightning discharges were compared with the Doppler radar data.The results show that the radiation sources were well associated with the storm development.When the storm was at the mature stage with an echo top of about 10.9 km,the radiation sources ranged from 5.2 to 8.3 km above mean sea level;when the storm gradually became weaker,with echo top of about 7.9 km,the radiation sources ranged from 3.0 to 5.9 km.In particular,one of the IC lightning discharges ranged from 3.0 to 4.9 km during the dissipation stage of the storm.The results also indicate that the radiation sources were closely associated with the high reflectivity region（25–50 dBZ）of the storm,which,to some extent,demonstrates the reliability of the location results,thereby showing that multi-station observations of fast electric field change sensors could be a useful tool for monitoring the storm development.Location errors from radiation sources were also compared with the radar data and the results of a simple simulation.It was found that the errors were getting smaller when the radiation sources approached the center of the detection network, and vice versa.Compared with the limited experimental observations,the simulation results were found capable of effectively reflecting the location errors.展开更多
Based on the VHF lightning locating system,a three-dimensional-space cell-gridded approach is used to extract the lighting channel and calculate the length of the channel.Through clustering of the located radiation so...Based on the VHF lightning locating system,a three-dimensional-space cell-gridded approach is used to extract the lighting channel and calculate the length of the channel.Through clustering of the located radiation sources and then extracting the lightning channel,it can accurately obtain the length of the channel.To validate the feasibility of the approach,a simulation experiment is designed,and it shows the length error is no more than 10%.The relationship between the NO production of per unit arc length and atmospheric pressure obtained in laboratory is applied to the NOX production of per unit flash length at different altitudes in this paper.The channel length and the NOX production of 11 negative cloud-to-ground flashes and 59 intracloud flashes in an isolated thunderstorm in the northeastern Qinghai-Tibet Plateau are calculated.The results show that the average channel lengths of per cloud-to-ground and intracloud flash are 28.9 and 22.3 km respectively;the average NOX productions of per cloud-to-ground and intracloud flash are 1.89×1025 and 0.42×1025 molecules,respectively.展开更多
基金the 100 Talents Program of the Chinese Academy of Sciencesthe Special Research Project for Public Welfare of China under Grant No.200704027-1the National Natural Science Foundation of China under Grant No.40930949
文摘Academy of Sciences,Beijing 100029 2 Lanzhou University,Lanzhou 730000 3 Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences,Lanzhou 730000 4 Nanjing University of Information Science＆Technology,Nanjing 210044 Using both fast and slow electric field change sensors and field mill,multi-station observations on lightning flashes over China inland plateau areas were conducted during the summer of 2004.All of the stations were synchronized by GPS with a time-resolution of±50 ns.Using the different time of arrival（DTOA）and based on the fast electric field change sensor,a lightning radiation location technique was developed.Radiation pulses in the initial stages of five intracloud（IC）lightning discharges which occurred on 20 August were analyzed.The results indicate that the technique developed could effectively locate the lightning radiation sources.Furthermore,the lightning discharges were compared with the Doppler radar data.The results show that the radiation sources were well associated with the storm development.When the storm was at the mature stage with an echo top of about 10.9 km,the radiation sources ranged from 5.2 to 8.3 km above mean sea level;when the storm gradually became weaker,with echo top of about 7.9 km,the radiation sources ranged from 3.0 to 5.9 km.In particular,one of the IC lightning discharges ranged from 3.0 to 4.9 km during the dissipation stage of the storm.The results also indicate that the radiation sources were closely associated with the high reflectivity region（25–50 dBZ）of the storm,which,to some extent,demonstrates the reliability of the location results,thereby showing that multi-station observations of fast electric field change sensors could be a useful tool for monitoring the storm development.Location errors from radiation sources were also compared with the radar data and the results of a simple simulation.It was found that the errors were getting smaller when the radiation sources approached the center of the detection network, and vice versa.Compared with the limited experimental observations,the simulation results were found capable of effectively reflecting the location errors.
基金supported by the National Natural Science Foundation of Chi-na(Grant Nos.41075002,40775004,41030960)R&D Special Fund for Public Welfare Industry(Meteorology)(Grant No.GYHY201006005-03)
文摘Based on the VHF lightning locating system,a three-dimensional-space cell-gridded approach is used to extract the lighting channel and calculate the length of the channel.Through clustering of the located radiation sources and then extracting the lightning channel,it can accurately obtain the length of the channel.To validate the feasibility of the approach,a simulation experiment is designed,and it shows the length error is no more than 10%.The relationship between the NO production of per unit arc length and atmospheric pressure obtained in laboratory is applied to the NOX production of per unit flash length at different altitudes in this paper.The channel length and the NOX production of 11 negative cloud-to-ground flashes and 59 intracloud flashes in an isolated thunderstorm in the northeastern Qinghai-Tibet Plateau are calculated.The results show that the average channel lengths of per cloud-to-ground and intracloud flash are 28.9 and 22.3 km respectively;the average NOX productions of per cloud-to-ground and intracloud flash are 1.89×1025 and 0.42×1025 molecules,respectively.
