依托中国气象局雷电野外科学试验基地人工引雷试验平台,利用自主研发的探测设备对发生于2023年7月18日的一次负极性人工触发闪电进行综合观测,获取了2次箭式先导-回击过程(RS1和RS2)高时间分辨、多参量互补的闪电电流、电场、磁场、甚高...依托中国气象局雷电野外科学试验基地人工引雷试验平台,利用自主研发的探测设备对发生于2023年7月18日的一次负极性人工触发闪电进行综合观测,获取了2次箭式先导-回击过程(RS1和RS2)高时间分辨、多参量互补的闪电电流、电场、磁场、甚高频(very high frequency,VHF)辐射以及X射线脉冲数据序列。结果表明:两次回击过程的下行先导进入气化钢丝通道及接地引起回击瞬间产生强烈的VHF和高能量X射线辐射,但其箭式先导发展速率存在较大差异,RS1先导发展速率达到10^(7) m·s^(-1)量级,对应较强的VHF辐射和连续型X射线脉冲;RS2先导发展速率达到10^(6) m·s^(-1)量级,相对于RS1二维发展速率低1个量级,VHF辐射和X射线脉冲相对较弱,且X射线呈分立脉冲特征;高能量X射线脉冲与先导沿钢丝通道下传接地引起回击的过程在时间上吻合,指示高能量X射线与回击启动过程间的直接关联,为揭示闪电回击阶段X射线的强场辐射机制提供了重要观测依据。展开更多
On 19 May 2022, an outbreak of 105 red sprites that occurred over South Asia was fortuitously recorded by two amateurs from a site in the southern Tibetan Plateau(TP), marking the highest number captured over a single...On 19 May 2022, an outbreak of 105 red sprites that occurred over South Asia was fortuitously recorded by two amateurs from a site in the southern Tibetan Plateau(TP), marking the highest number captured over a single thunderstorm in South Asia. Nearly half of these events involved dancing sprites, with an additional 16 uncommon secondary jets and at least four extremely rare green emissions called “ghosts” observed following the associated sprites. Due to the absence of the precise timing needed to identify parent lightning, a method based on satellite motion trajectories and star fields is proposed to infer video frame timestamps within an error of less than one second. After verifying 95 sprites from two videos, our method identified the parent lightning for 66 sprites(~70%). The sprite-producing strokes, mainly of positive polarity with peak currents exceeding +50 k A, occurred in the stratiform region of a mesoscale convective complex(MCC)that spanned the Ganges Plain to the southern TP, with a cloud area over 200 000 km2 and a minimum cloud-top black body temperature near 180 K. This observation confirms that thunderstorms in South Asia, akin to mesoscale convective systems(MCSs) in the Great Plains of the United States or coastal thunderstorms in Europe, can produce numerous sprites,including complex species. Our analysis bears important implications for characterizing thunderstorms above the southern TP and examining their physical and chemical effects on the adjacent regions, as well as the nature of the coupling between the troposphere and middle-upper atmosphere in this region.展开更多
文摘依托中国气象局雷电野外科学试验基地人工引雷试验平台,利用自主研发的探测设备对发生于2023年7月18日的一次负极性人工触发闪电进行综合观测,获取了2次箭式先导-回击过程(RS1和RS2)高时间分辨、多参量互补的闪电电流、电场、磁场、甚高频(very high frequency,VHF)辐射以及X射线脉冲数据序列。结果表明:两次回击过程的下行先导进入气化钢丝通道及接地引起回击瞬间产生强烈的VHF和高能量X射线辐射,但其箭式先导发展速率存在较大差异,RS1先导发展速率达到10^(7) m·s^(-1)量级,对应较强的VHF辐射和连续型X射线脉冲;RS2先导发展速率达到10^(6) m·s^(-1)量级,相对于RS1二维发展速率低1个量级,VHF辐射和X射线脉冲相对较弱,且X射线呈分立脉冲特征;高能量X射线脉冲与先导沿钢丝通道下传接地引起回击的过程在时间上吻合,指示高能量X射线与回击启动过程间的直接关联,为揭示闪电回击阶段X射线的强场辐射机制提供了重要观测依据。
基金supported by the National Natural Science Foundation of China (Grant No.42394122)CAS Project of Stable Support for Youth Team in Basic Research Field (YSRR-018)+1 种基金the National Key R&D Program of China (2023YFC3007703)the Chinese Meridian Project, and the International Partnership Program of Chinese Academy of Sciences (183311KYSB20200003)。
文摘On 19 May 2022, an outbreak of 105 red sprites that occurred over South Asia was fortuitously recorded by two amateurs from a site in the southern Tibetan Plateau(TP), marking the highest number captured over a single thunderstorm in South Asia. Nearly half of these events involved dancing sprites, with an additional 16 uncommon secondary jets and at least four extremely rare green emissions called “ghosts” observed following the associated sprites. Due to the absence of the precise timing needed to identify parent lightning, a method based on satellite motion trajectories and star fields is proposed to infer video frame timestamps within an error of less than one second. After verifying 95 sprites from two videos, our method identified the parent lightning for 66 sprites(~70%). The sprite-producing strokes, mainly of positive polarity with peak currents exceeding +50 k A, occurred in the stratiform region of a mesoscale convective complex(MCC)that spanned the Ganges Plain to the southern TP, with a cloud area over 200 000 km2 and a minimum cloud-top black body temperature near 180 K. This observation confirms that thunderstorms in South Asia, akin to mesoscale convective systems(MCSs) in the Great Plains of the United States or coastal thunderstorms in Europe, can produce numerous sprites,including complex species. Our analysis bears important implications for characterizing thunderstorms above the southern TP and examining their physical and chemical effects on the adjacent regions, as well as the nature of the coupling between the troposphere and middle-upper atmosphere in this region.
