Change in convection and thunderstorm occurrences over the Indian subcontinent during the COVID-19 pandemic
The unprecedented emission reductions during the COVID-19 lockdowns in 2020 provided a natural experiment to elucidate aerosol–radiation-cloud interactions and their effect on convective weather phenomena, particularly thunderstorm occurrence and lightning flash rate density (FRD), across the Indian...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2025-01-01
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| Series: | Environmental Research Letters |
| Subjects: | |
| Online Access: | https://doi.org/10.1088/1748-9326/adf863 |
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| Summary: | The unprecedented emission reductions during the COVID-19 lockdowns in 2020 provided a natural experiment to elucidate aerosol–radiation-cloud interactions and their effect on convective weather phenomena, particularly thunderstorm occurrence and lightning flash rate density (FRD), across the Indian subcontinent. The significant reduction in anthropogenic aerosol emissions, especially across the most polluted Indo-Gangetic Plain, led to a marked decrease in aerosol optical depth (AOD), altering regional cloud-aerosol interactions and radiative effects. A rise in ENSO-compensated lightning FRD and an increase in thunderstorm days (TDs) were associated with aerosol depletion, suggesting a favorable environment for convective initiation under relatively cleaner atmospheric conditions over the extremely polluted region. The reduced AOD likely led to enhanced surface heating and decreased upper-level warming, reversing the previously stable stratification caused by very high aerosol loading. This natural instability favored the formation of a greater number of widespread thunderstorms. However, the observed reduction in lightning FRD per TD during the pandemic year indicates that, while more storms formed, each storm exhibited lower electrification, likely due to diminished cloud condensation nuclei. Relatively lower aerosol concentrations can promote an increase in storm frequency through radiative destabilization of the atmosphere. However, these relatively cleaner conditions also tend to reduce lightning frequency within individual storms, as the limited presence of aerosols constrains non-inductive charging processes in clouds. Thus, environments with fewer aerosols are associated with more frequent storm development but a decrease in lightning flashes per storm, reflecting a complex interplay between atmospheric composition and convective electrification. These insights advance understanding of convective storm responses to aerosol variability and have important implications for future atmospheric electrification trends under changing emission scenarios. This dual effect highlights the complexity of aerosol–cloud-precipitation-electrification interactions. It has implications for understanding convective weather responses to air quality changes and future climate scenarios driven by aerosol management strategies. |
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| ISSN: | 1748-9326 |