Experimental Simulation of Red Sprites in a Laboratory

Over the past three decades,research of high-altitude atmospheric discharges has received a lot of attention.This paper presents the results of experimental modeling of red sprites during a discharge in low-pressure air.To initiate ionization waves in a quartz tube,an electrodeless pulse-periodic discharge fed by microsecond voltage pulses with an amplitude of a few kilovolts and a repetition rate of tens of kHz were formed.In this case ionization waves(streamers)have a length of tens of centimeters.The main plasma parameters were measured at various distances along the tube.The measurements confirm the fact that ionization waves propagate in opposite directions from the zone of the main electrodeless discharge,just as it happens during the formation of red sprites.

Red sprites over thunderstorms in the coast of Shandong Province,China

Red sprites, different from lightning flashes occurring in the troposphere, are large and brief dis-charges which appear in the altitude range from about 40 to 90 km above large thunderstorms and are usually caused by cloud-to-ground lightning discharges (CGs). A total of 17 sprites over two thunder-storms were first observed during the summer of 2007. One of the sprites occurred on July 28 above a thunderstorm in Guan County and the center of the storm was about 272 km from the observation site. The other sprites were recorded at the late night of August 1 and in the early morning of August 2, and the storm center was about 315 km away. All of the observed sprites occurred in cluster, and their appearances were very different, including 'columniform sprites', 'columniform sprites' with angel-like wings, 'carrot sprites', 'dancing sprites', etc. The duration of the sprites varied from a minimum of 40 ms to a maximum of 160 ms with a geometric mean (GM) of 61 ms. The time delay between parental positive cloud-to-ground lightning flashes (+CGs) and the associated sprites varied from 3.4 to 11.8 ms with a GM of 7.1 ms. The ratio of the number of +CGs to the total number of CGs during the time period with sprites was 7 times larger than that when no sprites occurred. Sprites did not appear fre-quently at the time when the convective activity is strong but when the thunderstorm starts to become weak.

华北地区一次中尺度对流系统上方的Sprite放电现象及其对应的雷达回波和闪电特征

利用低光度相机首次观测到了2013年7月31日华北地区一次中尺度对流系统(MCS)上空产生的中高层Sprite放电现象。结合闪电定位、天气雷达等同步观测,对一次MCS诱发的Sprite的形态学特征及其对应的母体闪电和雷暴系统的雷达回波特征等进行了详细分析。研究除发现了2例圆柱型、3例胡萝卜型和1例舞蹈型Sprite外,还发现了2例发光主体发育不完全的Y字型Sprite。估算的Sprite的底部平均高度低于61.8±3.5 km,顶部平均高度为84.3±6.8 km。Sprite持续时间算术平均值为25.7±9.8 ms,几何平均值为24.4 ms。Sprite的母体闪电均为正地闪,峰值电流在+62.5^+106.2 k A之间,算术平均值为+77.1±22.2 k A,是本次MCS所有正地闪平均峰值电流的1.4倍。Sprite母体闪电的脉冲电荷矩变化(i CMC)在+475^+922 C km之间,几何平均值为+571.0 C km。Sprite母体闪电发生在MCS雷达回波25~35 d BZ的层状云降水区,弱回波(<30 d BZ)面积的突然增加对Sprite的产生有重要指示作用。Sprite易发生在MCS成熟—消散阶段正地闪比例(POP)显著增加的时段。在本次MCS消散阶段中,有两个时间段可能有利于产生Sprite。在Sprite集中发生时间段,北京闪电综合探测网(BLNET)探测到的正地闪比例为54.2%,正地闪连续电流比例70.24%,连续电流持续时间为58.17±50.31 ms,有利于Sprite的产生。

Locating Parent Lightning Strokes of Sprites Observed over a Mesoscale Convective System in Shandong Province,China

In this paper, we report the location results for the parent lightning strokes of more than 30 red sprites observed over an asymmetric mesoscale convective system(MCS) on 30 July 2015 in Shandong Province, China, with a long-baseline lightning location network of very-low-frequency/low-frequency magnetic field sensors. The results show that almost all of these cloud-to-ground(CG) strokes are produced during the mature stage of the MCS, and are predominantly located in the trailing stratiform region, which is similar to analyses of sprite-productive MCSs in North America and Europe. Comparison between the location results for the sprite-producing CG strokes and those provided by the World Wide Lightning Location Network(WWLLN) indicates that the location accuracy of WWLLN for intense CG strokes in Shandong Province is typically within 10 km, which is consistent with the result based on analysis of 2838 sprite-producing CG strokes in the continental United States. Also, we analyze two cases where some minor lightning discharges in the parent flash of sprites can also be located, providing an approach to confine the thundercloud region tapped by the sprite-producing CG strokes.

2个北美冬青新品种组培快繁高效再生技术体系的建立

以北美冬青(Ilex verticillata L.)“Red Sprite”和“Winter Gold”2个品种的幼嫩枝条为外植体,建立了2个新品种的高效组培再生技术体系,为北美冬青新品种苗木的推广提供技术支持。结果表明:腋芽诱导的最佳培养基为MS+1.0 mg·L^(-1)6-苄氨基腺嘌呤(6-BA)+0.2 mg·L^(-1)萘乙酸(NAA),2个品种的诱导率都达到100%;最佳丛生芽增殖培养基为MS+0.1mg·L^(-1) NAA+0.5mg·L^(-1)6-BA+0.5 mg·L^(-1)氯吡苯脲(CPPU),其中品种“Red Sprite”的增殖系数达5.7,“Winter Gold”的增殖系数为4.5;最佳壮苗培养基为“Red Sprite”为MS+0.1 mg·L^(-1)NAA+0.5 mg·L^(-1)6-BA+1.0 mg·L^(-1)噻苯隆(thifenolone,TDZ)+1.0 mg·L^(-1)赤霉素(GA),培养25天时苗高达6.8 cm,“Winter Gold”的为MS+0.1 mg·L^(-1) NAA+0.5mg·L^(-1)6-BA+0.05mg·L^(-1) TDZ+1.0 mg·L^(-1)GA,25天时苗高达4.4 cm;最佳生根诱导培养基为1/2MS+0.4 mg·L^(-1) NAA+0.4 mg·L^(-1)吲哚丁酸(IBA)+1.0 g·L^(-1)活性炭(AC),“Red Sprite”品种生根率达95.0%,“Winter Gold”的生根率达97.0%;最佳移栽基质为泥炭土∶珍珠岩=3∶2,“Red Sprite”成活率为95.7%,“Winter Gold”的96.8%。

时变的准三维“红闪”电场模式研究

利用数值模拟的方法,研究了雷暴放电后,由雷暴电荷、感应电荷和晴天大气的背景电荷共同产生的准静电场(Quasi electrostaticfield ,简称QEF)的时变过程,以及准静电场对中性大气的加热和电离.结果表明:在考虑电离层电势和晴天大气背景电场的影响后,时变的准三维的准静电场(QEF)模式能较好地解释“红闪”(Redsprites)的时空特征,特别是能模拟出“红闪”中的一种———“闪晕”(spritehalo)向上弯曲的空间结构.

中国东北地区红色精灵的母体雷暴分析

红色精灵是发生在雷暴云上空的一种瞬态发光事件(Transient Luminous Events,TLEs),它们由地闪回击或与连续电流共同作用产生,这表明了对流层和低电离层之间的直接耦合关系。中国大陆的红色精灵观测研究主要在华北地区开展,为了进一步研究中国中高纬度地区的红色精灵现象,并揭示其与母体雷暴之间的相关性,故2017年夏季在吉林辽源开展了观测实验。本文介绍了利用低光度相机在东北地区捕捉到的26例红色精灵事件,并结合闪电定位、天气雷达等同步观测数据,对红色精灵及其母体雷暴特征进行了分析。结果表明,在26例红色精灵事件中,有17次(约2/3)产生于一次尺度较大的中尺度对流系统(Mesoscale Convective System,MCS),其余(约1/3)的红色精灵事件分别由三次尺度相对较小的中尺度对流系统诱发产生。红色精灵母体闪电均位于对流核心边缘区域,中尺度对流系统对流区后无大面积层状云降水区。此外,吉林辽源及安徽合肥同步记录的电磁场脉冲信号表明上述红色精灵事件均由正地闪回击产生。

2019年马六甲地区红色精灵观测及母体雷暴分析

红色精灵是一种发生于闪电放电活跃的雷暴云上空的中高层大气瞬态发光现象,它们通常由中尺度对流系统层状云降水区内的强地闪回击产生,是对流层和中间层之间的一种能量耦合过程。目前,有关中国南海及东南亚地区的红色精灵观测鲜有报道。为了进一步了解热带地区产生红色精灵事件的沿海性雷暴特征,于2019年利用低光度光学观测系统和低频磁场天线在马来西亚马六甲地区开展了地基观测。实验于11月9日、12月11日和12月15日三次在沿海雷暴上空共捕捉到7例红色精灵事件,其中包括4例圆柱型、2例胡萝卜型和1例舞蹈型。结合闪电定位、云顶亮温和低频磁场信号等同步数据,分析表明所有事件均由正极性地闪回击产生,且母体闪电回击位于雷暴对流区附近(云顶亮温≤210 K处),这可能是该地区产生红色精灵的沿海性雷暴的共同特征。此外,红色精灵生成期并不是闪电活动最强期,而是发生于闪电频数短暂降低后,这表明红色精灵的发生可能是该地区成熟雷暴中对流减弱的一个信号。

闪电引起的天电和红闪现象的模拟研究

用二维时变的电磁场模型,研究了闪电放电产生的天电和红闪现象.模拟结果表明:闪电放电产生的电场包括辐射场和准静电场.辐射场在地面-电离层波导中传播形成大气中的天电.由准静电场引起的N2分子第一个正波段的光辐射形成红闪现象.用模拟的方法表明,在红闪的空间结构发生变化的过程中,有明显“V”形结构;在红闪的整体机构中,中心部分是一个光强度相对较强的核,周围包着光强度相对较弱的晕.