The impacts of the COVID-19 lockdown on thunderstorm properties, influenced by changes in air quality, were investigated in Northeastern (Kohima, 25.66° N, 94.08° E) and Eastern (Rampurhat, 24.17° N, 87.78° E) India using seven years of ground-based observations. During the lockdown period (LP), Cloud-to-ground (CG) flashes decreased by 67 % and 51 % over Kohima and Rampurhat respectively. Reductions were noted in the number of thunderstorms and various intensity parameters such as duration, flashes per thunderstorm, Peak Flash Rate (PFR), IC: CG ratio, and lightning peak currents. Significant changes in anthropogenic aerosols were observed, with notable reductions in SO₂, NO₂, and PM₁₀ levels. Regardless of the specific raindrop formation mechanism in the two regions, higher concentrations of moderate to larger raindrops were observed during LP. Also, the mixed-phase region of thunderstorms shows a reduction in water content (both liquid and ice) in the mixed phase and the total column. Daily-scale analysis reveals non-linear associations between pollutant concentrations and CG flashes in both regions, with relative humidity (RH) potentially influencing these relationships. Overall, thunderstorm intensity parameters, mixed-phase processes, and rain DSDs were associated with reduced pollutant concentrations during LP. The similarity of trends in multiple parameters during PLP-LP-ALP aligns with established facts, affirming that reduced pollutants lead to noticeable changes in thunderstorm characteristics. The partial rebound of pollutants and other parameters during ALP remained below pre-lockdown levels, which might suggest the lasting impacts of reduced human activities on atmospheric conditions. Further research is necessary to confirm if these measures could mitigate climatic changes and potentially guide policymakers in addressing such changes.

中文翻译：

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评估印度东北部和东部 COVID-19 封锁期间的雷暴特征和空气质量


使用七年的地面观测，在印度东北部（科希马，北纬 25.66°，东经 94.08°）和东部（兰普哈特，北纬 24.17°，东经 87.78°）研究了 COVID-19 封锁对受空气质量变化影响的雷暴特性的影响。在锁定期间 （LP），科希马和兰普哈特的云对地 （CG） 闪光分别减少了 67% 和 51%。雷暴的数量和各种强度参数（如持续时间、每次雷暴的闪光次数、峰值闪光率 （PFR）、IC：CG 比率和雷电峰值电流）都有所减少。观察到人为气溶胶的显着变化，SO₂、NO₂ 和 PM₁₀ 水平显着降低。无论这两个地区的具体雨滴形成机制如何，在 LP 期间观察到更高浓度的中度至较大雨滴。此外，雷暴的混合相区域显示混合相和总柱中的含水量（液体和冰）减少。每日尺度分析揭示了两个地区的污染物浓度和 CG 闪光之间的非线性关联，相对湿度 （RH） 可能会影响这些关系。总体而言，雷暴强度参数、混合相过程和降雨 DSD 与 LP 期间污染物浓度降低相关。PLP-LP-ALP 期间多个参数趋势的相似性与既定事实一致，证实污染物减少会导致雷暴特征发生显着变化。ALP 期间污染物和其他参数的部分反弹仍低于封锁前的水平，这可能表明人类活动减少对大气条件的持久影响。 需要进一步的研究来确认这些措施是否可以缓解气候变化，并可能指导政策制定者应对此类变化。