Land-atmospheric coupling amplify the flash drought intensity in India

Concurrent high temperature and low soil moisture during flash drought (FD) can become significantly hazardous, posing a devastating impact on human health, agriculture, and the ecosystem. Strong land-atmospheric coupling influences the intensity of flash drought events. Despite flash drought having detrimental impacts, the soil moisture (SM)-temperature (T) relationship and their characteristics are poorly understood in a coupled land-atmospheric scenario. Using variables from ERA5 reanalysis, we identify the major flash drought events and evaluate the SM-T coupling in India for the 1980-2019 period. We find that the summer monsoon season experiences most flash drought events during the monsoon breaks. Temperature anomalies and FD intensities remained strongly correlated (r= 0.78 and r= 0.67, respectively) with the SM-T coupling. Central India and Indo-Gangetic Plain experienced higher FD intensity and SM-T coupling compared to other parts of the country. Moreover, the SM-T coupling during flash drought increased by three-fold against the normal condition with an increasing trend over India. The strengthening of SM-T coupling is attributed to the increasing temperature and potential of declining soil moisture to influence the partitioning of the heat budget in the warming climate. Overall, we find that SM-T coupling is a key factor in deciding the intensity of flash drought, which may further increase under the future warming climate. Exacerbated flash drought intensity can severely affect crop production, irrigation demand, and ecological health.