Hidden Waves Amplify Rainfall in India

Invisible atmospheric disturbances known as tropical waves have been identified as a major factor in enhancing heavy rainfall along India's west coast. Researchers discovered that Kelvin, Rossby, and Mixed Rossby-Gravity waves play a significant role by organizing deep convective cloud systems and increasing moisture convergence over the Arabian Sea and the Western Ghats.

Among these, Rossby waves demonstrated the strongest influence, capable of amplifying extreme rainfall over land by an estimated 20-60%. This comprehensive assessment is the first to detail the impact of these tropical waves on rainfall extremes in the region. The findings are particularly relevant for Kerala, a state that has experienced severe floods and landslides in recent years.

The study observed a correlation between intense tropical wave activity and catastrophic rainfall events. Specifically, the devastating floods of 2018 and 2019 in Kerala coincided with strong Rossby wave activity. Furthermore, the deadly Wayanad landslides in 2024 were associated with intense Kelvin wave activity.

This research holds significant promise for enhancing early warning systems. Unlike unpredictable local thunderstorms, tropical wave activity can often be monitored days in advance. Integrating these signals into weather forecasting models could provide essential lead time for anticipating heavy rainfall. This improved preparedness is vital as climate change continues to intensify the hydrological cycle, leading to more extreme weather events.