This paper discusses the temporal and spatial distribution characteristics of cloud-to-ground (CG) lightning activity over the Qinghai-Tibetan Plateau (QTP) from 2009 to 2018 and their dependence on meteorological factors. It is found that (1) the number of CG flashes fluctuates, reaches a maximum in 2014, and then gradually decreases. The main active period of CG lightning is from June to September each year, after which it decreases rapidly. CG lightning is mainly distributed in the valley areas at around 4800 m above sea level at Lhasa, Nagqu, and Chamdo, and there are differences in the characteristics of CG activity in these three areas. The peak of daily CG lightning occurs at 1000 UTC, and the lowest value is at 0400 UTC. The distribution of CG lightning in all seasons has obvious differences in peak time and the proportion of positive CG (+CG) lightning, with the ratio of +CG lightning to total CG lightning flashes in spring and autumn exceeding 50%. (2) The ratio of +CG lightning to total CG lightning flashes over the QTP is influenced by a combination of thermodynamic and microphysical factors. Over the QTP, greater vertical wind shear leads to the movement of upper positive charges and promotes the occurrence of +CG lightning. Also, the higher total column liquid water content implies higher cloud water content in the warm-cloud region, and the higher cloud-base height implies a thicker warm-cloud region, which is not conducive to the occurrence of +CG lightning. (3) During high-value years (in this study, 2010, 2012, 2014, and 2016), the midlatitude (30°N–60°N) high pressure is strong and the plateau is situated at the intersection of the East Asian and South Asian monsoons and the cold air from the northwest, which strengthens the water vapor convergence and increases the frequency of thunderstorms. When the plateau is under the control of the southerly monsoon from June to September every year, its atmosphere is full of water vapor and lightning activity is accordingly high, with the proportion of +CG lightning being about 10%. Meanwhile, in the remaining months, when controlled by the westerly wind belt, the plateau’s water vapor condition is poor, the level of lightning activity weakens, and the proportion of +CG lightning gradually increases to more than 50%.

中文翻译：

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青藏高原雷暴特征及其闪电活动

本文讨论了2009-2018年青藏高原（QTP）云对地（CG）闪电活动的时空分布特征及其对气象因子的依赖。发现（1）CG闪光次数有波动，2014年达到最大值，然后逐渐减少。CG闪电的主要活跃期是每年的6-9月，之后迅速减少。地气闪电主要分布在拉萨、那曲、昌都海拔4800米左右的河谷地区，三地地气活动特征存在差异。每日 CG 闪电的峰值出现在 1000 UTC，最低值在 0400 UTC。各季节地雷分布在高峰时间和正地地(+CG)闪电的比例上存在明显差异，春秋两季地地闪电占总地地闪电的比例超过50%。(2) 青藏高原上+CG闪电与总CG闪电的比率受热力学和微观物理因素的综合影响。在青藏高原上空，较大的垂直风切变导致上部正电荷移动，促进了+CG闪电的发生。同时，柱状总液态水含量越高，说明暖云区云水含量越高，云底高度越高，说明暖云区越厚，不利于+CG闪电的发生。(3) 在高价值年份（本研究中，2010、2012、2014 和 2016 年），中纬度（30°N-60°N）高压强，高原处于东亚和南亚季风与西北冷空气的交汇处，加强了水汽辐合，增加了雷暴。每年6-9月高原受偏南季风控制时，大气中充斥着水汽，闪电活动也相应高，+CG闪电的比例约为10%。同时，在剩余月份，受西风带控制，高原水汽条件较差，闪电活动程度减弱，+CG闪电比例逐渐上升至50%以上。