Atmospheric Rivers
Atmospheric rivers (ARs) are long, narrow regions in the atmosphere that transport significant amounts of water vapor. These corridors, often thousands of kilometers long but less than a thousand kilometers wide, act like rivers in the sky. Originating from the warm oceans, they move poleward, propelled by strong winds, and are a significant factor in the distribution of intense rainfall during their landfall.
Impact on India’s Monsoon and Flooding
In India, ARs have been linked to a notable increase in both the intensity and frequency of monsoon rains. This phenomenon contributes to very heavy and extremely heavy rainfall across the country, as highlighted by recent India Meteorological Department (IMD) reports. For instance, in July 2023, an unusually high number of weather stations recorded extreme rainfall, a pattern that continued into 2024.
Scientific Studies and Findings
Research has shown a clear association between ARs and severe weather events in India. A pivotal study published in ‘Nature’ in 2023 revealed that 70% of major floods in India over the past 35 years were associated with ARs. Furthermore, a 2021 study pinpointed a multi-day AR event as the primary cause of record-breaking floods in Kerala in 2018, underscoring the critical impact of these atmospheric phenomena on regional climates.
Changes Over Time
The frequency and intensity of ARs over India have increased, with the maximum and minimum levels of vertically integrated vapor transport (IVT) showing significant growth since the 1950s. This trend indicates not only more frequent but also more intense AR events, affecting the Indian subcontinent with more severe weather patterns, including landslides and flash floods.
The Role of Climate Change
Climate scientists from the Indian Institute of Tropical Meteorology, suggest that fluctuations in moisture transport towards the Indian subcontinent are becoming more pronounced. These variations lead to heavy downpours over short periods, directly contributing to the increasing occurrences of landslides and flash floods across India.
This evolving understanding of atmospheric rivers and their impact on India’s climate is crucial for developing more effective strategies to mitigate the adverse effects of extreme weather conditions and enhance the country’s resilience to climate change.
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