红色精灵是发生在雷暴云上空的一种大尺度瞬态放电发光现象，它们通常出现在地面上空40～90 km之间，是由地闪回击和随后可能存在的连续电流产生的。目前，由于综合同步观测资料较少，与夏季红色精灵相比，全世界对冬季红色精灵的研究屈指可数。2008年12月27～28日，受高空槽及低层暖湿气流的影响，北美阿肯色州地区爆发了一次冬季雷暴天气过程，搭载于FORMOSAT-2卫星上的ISUAL（Imager of Sprites and Upper Atmospheric Lightning）探测器有幸在这次雷暴上空记录到了两例红色精灵事件。本文利用ISUAL获取的红色精灵观测资料、多普勒天气雷达资料、美国国家闪电定位资料、超低频磁场数据、美国国家环境中心/气候预测中心提供的云顶亮温和探空数据等综合观测数据，对产生红色精灵的这次冬季雷暴特征和相关闪电活动规律进行了详细研究。结果表明，在两例红色精灵中，ISUAL均未观测到伴随的“光晕（halo）”现象，第一例为“圆柱状”红色精灵，第二例红色精灵由于发光较暗，无法判断其具体形态。产生红色精灵的母体雷暴是一次中尺度对流系统，该系统于27日15:00（协调世界时，下同）左右出现在阿肯色州北部附近，并自西向东移动。23:59系统发展到最强，最大雷达反射率因子（55～60 dBZ）的面积达到339 km2，之后开始减弱。03:03雷暴强度有所增加，随后云体便逐渐扩散，雷暴开始减弱，并在11:00完全消散。两例红色精灵发生分别在04:46:05和04:47:14，此时雷暴处于消散阶段，正负地闪频数均处于一个较低水平且正地闪比例显著增加，并且多位于云顶亮温-40℃～-50℃的层状云区上空。红色精灵的出现伴随着30～35 dBZ回波面积的增加。在红色精灵发生期间，雷达反射率大于40 dBZ的面积减少，10～40 dBZ的面积增加，表明红色精灵的产生与雷暴对流的减弱和层状云区的发展有关，这与已有的夏季红色精灵的研究结果类似。红色精灵的母体闪电为正地闪单回击，位于中尺度对流系统雷达反射率为25～35 dBZ的层状云降水区，对应的雷达回波顶高分别为2.5 km和5 km，峰值电流分别为+183 kA和+45 kA。根据超低频磁场数据估算两个母体闪电的脉冲电荷矩变化（iCMC）分别为+394 C km和+117 C km。超低频磁天线记录到了第一例红色精灵内部的电流信号，表明这例红色精灵放电很强。
Red sprites are large-scale transient luminous events (TLEs) that usually occur between about 40 and 90 km altitudes above thunderstorms, and they are caused by cloud-to-ground (CG) lightning strokes and subsequent continuous current. Compared with studies that focus on sprites that occur in summer, those focusing on winter sprites are fewer due to limited comprehensive synchronous observation data. Influenced by the upper trough and warm, moist airflow at low level, a thunderstorm occurred in Arkansas, North America, on December 27–28, 2008. The Imager for Sprites and Upper Atmospheric Lightning (ISUAL) aboard the FORMOSAT-2 satellite could record two red sprite events. Using the red sprites optical observation data obtained by ISUAL, Doppler weather radar data, National Lightning Location data, ultra-low frequency magnetic field data, and cloud-top brightness temperature data provided by the National Environmental Center/Climate Prediction Center of the United States and the sounding data, this paper presents a detailed study of the characteristics of the winter thunderstorm that produced the red sprites and the related lightning activity. The results show that ISUAL did not record the halo that accompanied the two red sprites. The first was a columnar sprite, and the specific morphology of the second could not be determined because of its dim light. The parent thunderstorm of the red sprites was a mesoscale convective system (MCS), which appeared around 1500 UTC on the 27th near northern Arkansas and moved from west to east. The thunderstorm became stronger at about 2359 UTC, and the area of maximum radar reflectivity (55–60 dBZ) reached 339 km2 and then began to weaken. At 0303 UTC, the thunderstorm intensity increased, then the cloud gradually spread, and the thunderstorm began to weaken and completely dissipated at 1100 UTC. The first recorded sprite occurred at 0446:05 UTC, and the second at 0447:17 UTC. They tended to be produced in the dissipation stage of the MCS, when the frequency of the positive and negative CG lightning was low and the Percentage Of Positive CG to total CG (POP) increased significantly, and they were mostly over the stratiform cloud area with a brightness temperature of -40℃–-50℃. The sprite production was accompanied by an increase in the echo area of 30–35 dBZ. The area of radar reflectivity larger than 40 dBZ decreased, and the area of 10–40 dBZ increased during the sprite time window, suggesting that the sprite production was the decay of the thunderstorm and that the area of the stratiform region developed, which is consistent with the results of previous studies on summer sprites. The parent CG flash of red sprites was positive and with a single return stroke, and it was located in the trailing stratiform region of the MCS, where the radar reflectivity ranged from 25 to 35 dBZ. The corresponding radar echo top heights were 2.5 km and 5 km, and the peak currents were +183 kA and +45 kA, respectively. Based on the ultra-low frequency magnetic field data, the impulse charge moment changes (iCMCs) of two parent lightning discharges were estimated to be +394 C km and +117 C km. The ultra-low frequency magnetic antenna recorded the internal current signal of the first red sprite, indicating that the red sprite was strongly discharged.
钟丽华,杨静,陆高鹏,王庸平,何其佳,郄秀书.北美地区一次冬季中尺度对流系统上空红色精灵现象的空间观测及其母体雷暴分析.大气科学,2020,44(5):997~1012 ZHONG Lihua, YANG Jing, LU Gaopeng, WANG Yongping, HE Qijia, QIE Xiushu. Spatial Observation of Red Sprites over a Winter Mesoscale Convective System in North America and the Analysis of Its Parent Thunderstorm. Chinese Journal of Atmospheric Sciences (in Chinese),2020,44(5):997~1012复制