Combined with the existing stochastic lightning parameterization scheme, a classic tripole charge structure in thunderstorms is assumed in the paper, and then 2-dimensional fine-resolution lighting discharge simulatio...Combined with the existing stochastic lightning parameterization scheme, a classic tripole charge structure in thunderstorms is assumed in the paper, and then 2-dimensional fine-resolution lighting discharge simulations are performed to quantitatively investigate the effect of lower positive charge(LPC) on different types of lightning. The results show:(1) The LPC plays a key role in generating negative cloud-to-ground(CG) flashes and inverted intra-cloud(IC) lightning, and with the increase of charge density or distribution range of LPC region, lightning type changes from positive polarity IC lightning to negative CG flashes and then to inverted IC lightning.(2) Relative to distribution range of charge regions, the magnitude of charge density of the LPC region plays a dominant role in lightning type. Only when the maximal charge density value of LPC region is within a certain range, can negative CG flashes occur, and the occurrence probability is relatively fixed.(3) In this range, the charge density and distribution range of LPC region jointly determine the occurrence of negative CG flashes, which has a linear boundary with the trigger condition of IC lightning.(4) The common effect of charge density and distribution range of the LPC region is to change the distribution of positive potential well of bottom part of thunderstorms, and inverted IC lightning occurs when the initial reference potential is close to 0 MV, and negative CG flashes occur when the initial reference potential is far less than 0 MV.展开更多
Particle bursts （PBs）, the phenomena characterized by short-term increases of particle counting rates （CRs）, were observed by space-borne radiation belt particle detectors. With the electron CR data obtained by Na...Particle bursts （PBs）, the phenomena characterized by short-term increases of particle counting rates （CRs）, were observed by space-borne radiation belt particle detectors. With the electron CR data obtained by National Oceanic and Atmospheric Ad- ministration （NOAA）-18 satellite, the occurrence of PBs in the inner belt （I〈~L〈2 and B〉20.5 gT） were derived for years 2006-2011. The monthly occurrence number of PBs exhibits a strong maximum in northern summer （May-August）. In associ- ation with global lightning data, the seasonal occurrence of PBs is found to be consistent with the lightning activity, especially if only lightning flashes at latitudes 〉20~ are taken into account. The positive correlation between PBs and mid-latitude light- ning discharges indicates the role of lightning-induced whistler waves, and is consistent with the expected pitch-angle scatter- ing by wave-particle interactions. The contribution of lightning is so significant that it forms a non-negligible seasonal back- ground of PBs. If one connects PBs to seismoelectromagnetic emissions （SEME） in attempt to find the earthquake precursor, the lightning background needs to be considered with great care.展开更多
基金supported by the National Basic Research Program of China(Grant No.2014CB441403)the National Natural Science Foundation of China(Grant No.41175003)Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘Combined with the existing stochastic lightning parameterization scheme, a classic tripole charge structure in thunderstorms is assumed in the paper, and then 2-dimensional fine-resolution lighting discharge simulations are performed to quantitatively investigate the effect of lower positive charge(LPC) on different types of lightning. The results show:(1) The LPC plays a key role in generating negative cloud-to-ground(CG) flashes and inverted intra-cloud(IC) lightning, and with the increase of charge density or distribution range of LPC region, lightning type changes from positive polarity IC lightning to negative CG flashes and then to inverted IC lightning.(2) Relative to distribution range of charge regions, the magnitude of charge density of the LPC region plays a dominant role in lightning type. Only when the maximal charge density value of LPC region is within a certain range, can negative CG flashes occur, and the occurrence probability is relatively fixed.(3) In this range, the charge density and distribution range of LPC region jointly determine the occurrence of negative CG flashes, which has a linear boundary with the trigger condition of IC lightning.(4) The common effect of charge density and distribution range of the LPC region is to change the distribution of positive potential well of bottom part of thunderstorms, and inverted IC lightning occurs when the initial reference potential is close to 0 MV, and negative CG flashes occur when the initial reference potential is far less than 0 MV.
基金supported by the National Basic Research Program of China("973" Project)(Grant Nos.2012CB957801,2011CB811405)the National Natural Science Foundation of China(Grant Nos.41274155,40904036)+1 种基金the Public Science and Technology Research Funds Projects of Ocean,State Oceanic Administration of China(Grant No.201005017)the Specialized Research Fund for State Key Laboratories
文摘Particle bursts （PBs）, the phenomena characterized by short-term increases of particle counting rates （CRs）, were observed by space-borne radiation belt particle detectors. With the electron CR data obtained by National Oceanic and Atmospheric Ad- ministration （NOAA）-18 satellite, the occurrence of PBs in the inner belt （I〈~L〈2 and B〉20.5 gT） were derived for years 2006-2011. The monthly occurrence number of PBs exhibits a strong maximum in northern summer （May-August）. In associ- ation with global lightning data, the seasonal occurrence of PBs is found to be consistent with the lightning activity, especially if only lightning flashes at latitudes 〉20~ are taken into account. The positive correlation between PBs and mid-latitude light- ning discharges indicates the role of lightning-induced whistler waves, and is consistent with the expected pitch-angle scatter- ing by wave-particle interactions. The contribution of lightning is so significant that it forms a non-negligible seasonal back- ground of PBs. If one connects PBs to seismoelectromagnetic emissions （SEME） in attempt to find the earthquake precursor, the lightning background needs to be considered with great care.
