Aerosols emitted in densely populated and industrialized Indo-Gangetic Plain, one of the most polluted regions in the world, modulate regional climate, monsoon, and Himalayan glacier retreat. Thus, this region is important for understanding aerosol perturbations and their resulting impacts on atmospheric changes during COVID-19 lockdown period, a natural experimental condition created by the pandemic. By analyzing 5 years (2016–2020) data of aerosols and performing a radiative transfer calculation, we found that columnar and near-surface aerosol loadings decreased, leading to reductions in radiative cooling at the surface and top of the atmosphere and atmospheric warming during lockdown period. Further, satellite data analyses showed increases in cloud optical thickness and cloud-particle effective radius and decrease in lower tropospheric air temperature during lockdown period. These results indicate critical influences of COVID-19 lockdown on regional climate and water cycle over Indo-Gangetic Plain, emphasizing need for further studies from modeling perspectives.

中文翻译：

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COVID-19 对人口稠密和高度污染的印度恒河平原的气溶胶负荷和辐射预算扰动：对云特性和气温的影响


人口稠密和工业化的印度恒河平原是世界上污染最严重的地区之一，其排放的气溶胶调节了区域气候、季风和喜马拉雅冰川消退。因此，该区域对于了解 COVID-19 封锁期间的气溶胶扰动及其对大气变化的影响非常重要，这是大流行造成的自然实验条件。通过分析5年（2016-2020）气溶胶数据并进行辐射传输计算，我们发现柱状和近地表气溶胶负荷减少，导致锁定期间大气表面和顶部的辐射冷却减少以及大气变暖时期。此外，卫星数据分析显示，锁定期间云光学厚度和云粒子有效半径增加，对流层较低气温降低。这些结果表明，COVID-19 封锁对印度恒河平原的区域气候和水循环产生了重大影响，强调需要从建模角度进行进一步研究。