Atmospheric rivers that make landfall in India are associated with flooding

Abstract

Atmospheric rivers often cause extreme precipitation at landfall, leading to floods. However, the underlying physical mechanism of atmospheric rivers and their linkage with flooding in India remain unrecognized. Here we use reanalysis and observations to diagnose the drivers of atmospheric rivers and unravel their crucial role in extreme precipitation and floods during 1951–2020. Moisture transport has significantly increased during 1951–2020, which is associated with strengthening winds that transport water vapor from the oceans. However, while there is a suggestive corresponding increase in the frequency of atmospheric rivers, it is not statistically significant. The atmospheric river catalogue that we developed shows that about 65% of landfalling atmospheric river were linked to floods during the 1985–2020 period. In addition, seven of India’s ten most severe floods in the summer monsoon season with substantial mortality were associated with atmospheric rivers. Better understanding and prediction of atmospheric rivers is crucial for flood mitigation.