Observations of NO2 and O3 during thunderstorm activity using visible spectroscopy

Simultaneous observations for the total column densities of NO2, O3 and H2O were carried on using the porta-ble Spectrometer (438-450 nm and 400-450 nm) and the visible Spectrometer (544.4-628 nm) during premonsoon thunderstorms and embedded hail storm activity at Pune (18o32’N & 73o51’E), India. These observations confirm the fact that there is an increase in O3 and NO2 column densities during thunderstorms. The increase in O3 was observed following onset of thunderstorm, while the increase in NO2 was observed only after the thunder flashes occur. This implies that the production mechanisms for O3 and NO2 in thunderstorm are different. The observed column density of NO2 value (1 to 3 × 1017molecules · cm-2) during thunderstorm activity is 10 to 30 times higher than the value (1 × 1016molecules · cm-2) of a normal day total column density. The spectrometric observations and observations of thunder flashes by electric field meter showed that 6.4 × 1025molecules / flash of NO2 are produced. The increased to-tal column density of ozone during thunderstorm period is 1.2 times higher than normal (clear) day ozone concentra-tion. The multiple scattering in the clouds is estimated from H2O and O2 absorption bands in the visible spectral re-gion. Considering this effect the calculated amount of ozone added in the global atmosphere due to thunderstorm ac-tivity is 0.26 to 0.52 DU, and the annual production of ozone due to thunderstorm activity is of the order of 4.02 × 1037 molecules /year. The annual NO2 production may be of the order of 2.02 × 1035molecules / year.     

贵州铜仁两次大范围冰雹过程的对比分析

利用常规观测、地面加密自动站降水、雷达观测及NCEP 1°×1°再分析资料等对2016年4月2日和15日发生在贵州省铜仁市的两次冰雹天气过程进行对比分析,结果发现:(1)降雹由地面发展雷暴和高架雷暴产生,前者在暖区产生,后者在锋后冷垫上形成;(2)前者由地面辐合线锋生激发对流,后者由逆温层顶850 hPa切变线触发,两者的强上升运动区域明显不同;(3)雷达回波形态上前者为弓形回波,强对流回波从近地面发展至10 km左右高度,"三体散射长钉"和有界弱回波区等现象明显;而后者为多单体风暴,有界弱回波区特征明显,强对流回波柱密实而深厚,回波质心较高。     

深圳云地闪时空分布特征研究

利用1997-2011年云地闪电定位探测资料和深圳国家基本气象站1953-2011年的观测资料,对深圳云地闪电（简称地闪）时空分布特征和雷暴日变化趋势进行分析。结果表明：深圳雷暴日数近59 a来呈下降趋势,小波分析显示年雷暴日数存在5 a周期和10-15 a的次周期;年内地闪频次特征表现为6月和8月双峰形特征,8月为全年地闪次数最多的月份;雷暴的活跃程度与太阳辐射热力条件密切相关,地闪活动高峰出现在14-18时;深圳地闪密度呈现西北多、东南少,内陆地区多、沿江沿海地区少的分布特征,地形、海陆分布是影响地闪空间分布的重要原因;地闪强度的分析表明,正、负闪月平均强度峰值分别出现在2月和6月,负闪强度低于正闪,正、负闪日强度峰值均未出现在频次峰值时段。     

东北冷涡内部中尺度涡旋引起的冰雹天气数值模拟

利用NCEP格点资料模拟了2011年8月21日沈阳地区的冰雹天气过程,结合机场自动观测数据、多普勒雷达资料和卫星云图等分析了冰雹的形成机制。结果表明：此次冰雹天气是由冷涡内部的中尺度涡旋引起的,卫星云图上的中尺度云团是中尺度涡旋的产物;0℃等温线位于600 hPa,-20℃位于450 hPa附近,两者之间厚度在2KM左右;冰雹发生前,斜升气流的最大上升速度为20 m·s^-1以上,水汽累积区位于0℃层以上,保证了水分累积区都由过冷水滴组成;高层干冷空气倾斜下侵到中低层的暖湿空气中,对强对流的发生发展起到了至关重要的作用;低层MPV1为强对流提供了对流不稳定机制,中层MPV2为强对流提供了对称不稳定机制,高层两种不稳定共存,均为对流发展贡献力量;对流有效位能积累、释放随时间的演变对冰雹的出现有一定的指示意义;10:30多普勒雷达图显示回波强度随高度增强,速度图上存在西南低空急流,有利于对流的发展。     

Thunderstorms,Lightning, Sprites and Magnetospheric Whistler-Mode Radio Waves

Thunderstorms and the lightning that they produce are inherently interesting phenomena that have intrigued scientists and mankind in general for many years. The study of thunderstorms has rapidly advanced during the past century and many efforts have been made towards understanding lightning, thunderstorms and their consequences. Recent observations of optical phenomena above an active lightning discharge along with the availability of modern technology both for data collection and data analysis have renewed interest in the field of thunderstorms and their consequences in the biosphere. In this paper, we review the electrification processes of a thunderstorm, lightning processes and their association with global electric circuit and climate. The upward lightning discharge can cause sprites, elves, jets, etc. which are together called transient luminous events. Their morphological features and effects in the mesosphere are reviewed. The wide spectrum of electromagnetic waves generated during lightning discharges couple the lower atmosphere with the ionosphere/magnetosphere. Hence various features of these waves from ULF to VHF are reviewed with reference to recent results and their consequences are also briefly discussed.     

雷暴激发的环状重力波在中高层大气中的传播特征

本文使用中国科学院国家空间科学中心——子午工程朔州观测站的全天空气辉成像数据,以及FY-2气象卫星云顶亮温数据（Black Body Temperature,TBB）,气象再分析数据和地闪数据,研究了2013年8月10日（LT）发生在内蒙古地区的雷暴活动激发的中高层环状重力波（Concentric Gravity Waves,CGWs）事件.根据最小二乘法的拟合结果和色散关系理论曲线,确定了激发中高层环状重力波的强对流系统,该对流中心位于内蒙古自治区中部（108.9°E,40.47°N）,重力波激发于雷暴初期,此时TBB低于220 K的深对流面积较小,随着时间的推移,该次雷暴活动越来越强,深对流面积在23：00达到最大,在23：30-24：00 LT时闪电频数最高,达到120.7 fl/min,随后深对流逐渐消散.在中高层87 km处OH（羟基）气辉层观测到的一次CGWs事件的两组波纹,分别沿水平方向传播了149.64 km和174.25 km,相应位置处的水平波长分别为12.67 km和16.75 km,周期分别为8.56 min和10.72 min,激发时间分别为19：34 LT和19：40 LT;随着水平传播距离的增加,CGWs水平波长增大.     

Contribution of the ground corona ions to the convective charging mechanism

The convective charging mechanism of thunderclouds is based on the vertical transport of space charge generated by corona from ground irregularities under the influence of the surface electric field. The present work estimates the amount of charge which is expected to reach cloud base by conduction and convection processes during the lifetime of a thunderstorm. This estimate is made using the numerical model PICASSO, previously designed to characterize the evolution of this corona space charge between ground level and cloud base. Experimentally determined values of surface electric field are introduced into the model in order to initiate the computation. These values are based on six events documented during four different field experiments carried out in Florida and in France. As an upper limit, the convective transport is uniformly applied as a linearly increasing vertical air speed profile and competes with the conductive transport. The fraction of the positive charge generated at the surface by corona which finally reaches the upper limit of the layer varies between 26 and 86%, essentially depending on the electric field evolution at altitude. Assuming that the vertical transport conditions remain the same over an area of 10 km×10 km, the overall charge amount can be roughly estimated. It ranges between about 63 and over 300 C. Because the present assumptions probably lead to an overestimate of these amounts, such a range suggests that the convective charging mechanism is unlikely to be able to account for the major electrification process of the thundercloud. However, it could be considered as a relevant mechanism contributing to the lower positive charge center of the thundercloud, often observed close to cloud base.     

基于TRMM卫星多传感器资料揭示的亚洲季风区雷暴时空分布特征

利用16年（1998-2013）的热带降水测量任务卫星（TRMM）降水雷达和闪电成像仪等多传感器观测资料,分析了亚洲季风区内雷暴和强雷暴的空间分布、季节变化及日变化等气候特征.文中取闪电数大于1的雷达降水特征为雷暴,并将闪电频数在前10%的雷暴定义为强雷暴.结果表明：雷暴活动主要集中在陆地及近海区域,陆地与海洋上的雷暴密度之比约为4.4：1,强雷暴密度之比约为7.4：1.0-10°N纬度带内雷暴数占总雷暴的比例最大（占总数的31.7%）,而强雷暴则在20°N-30°N区间最为活跃（34.5%）.雷暴与闪电密度的空间分布在低纬度区域（0-30°N）较为一致,但在中纬度地区（30°N-36°N）呈现出不同的分布特征,即从西部的青藏高原向东部的江淮流域,雷暴密度逐渐减少但闪电密度逐渐增加;而强雷暴与闪电密度的空间分布基本一致.受亚洲夏季风活动影响,低纬度地区强雷暴更容易发生在春季,强中心位于喜马拉雅山南麓东端,次中心位于中南半岛,而中纬度地区在夏季最为活跃,强中心和次中心则分别位于喜马拉雅山南麓西端和中国江淮流域.陆地上雷暴主要集中在午后至傍晚,少数区域受局地环流和气象条件的影响夜雷暴活动频繁,而海洋上雷暴更易发生在午夜至清晨.     

飑的判断与记录

“飑”是一种较复杂的天气,发生频次较少。本文通过对飑的特征的分析,总结了判断的方法,并结合典型个例分析飑与雷暴过境的区别,对其记录方法加以说明,对观测员正确判断记录有一定的借鉴作用。     

凤翔站２００５—２００６年自动气象站观测资料质量评估分析

本文对2010年6月2日18时-19时期间雷暴过程中大气电场监测数据进行分析,并与闪电定位资料对比后,得出闪电发生前大气电场值会出现波动并逐渐增大,雷电发生时大气电场会出现极值和脉冲,雷云消散后大气电场又恢复到平稳状态;大气电场的监测对雷电的预警预报有着非常重要的作用。