Assessing the impact of ENSO on Vegetation during the Kharif Season over India

The El Niño–Southern Oscillation (ENSO) is the strongest driver of monsoon variability that significantly affects agricultural production in India. This study evaluates the teleconnections between strong ENSO events during 1982-2017; the vegetation conditions and water availability over the Indian region. For this purpose, various indices (i.e., Vegetation Condition Index (VCI), Vegetation Health Index (VHI), Precipitation Condition Index (PCI), Soil Moisture Index (SMCI), Temperature Condition Index (TCI), and Soil Moisture Agricultural Drought Index (SMADI)) are evaluated to determine agricultural drought conditions during the Kharif season (July to October) in India. Results indicate that vegetation conditions are strongly associated with Pacific Sea Surface Temperature (SST) and vary with geographical conditions. The correlation analysis between root zone soil moisture, precipitation, temperature, and vegetation conditions with SST delineates strong feedback with 1-2 months of lead time. Most of the indices show that drought severity was mainly pronounced in most of the parts of Peninsular, Central Northeast (particularly in Indo-Gangetic Plain), and West Central India during strong El Niño years. On the contrary, during strong La Niña years, some areas also experienced drought conditions in the Indo-Gangetic. Further investigation through empirical orthogonal teleconnections (EOT) and correlation analysis confirms the similar teleconnection impacts in the Indian region. These findings contribute to the understanding of drought dynamics in Indian regions. However, due to extreme heat as evident from TCI, the vegetation-based indices were not always consistent with precipitation and soil moisture-based indices. This study highlights that the impact of ENSO on agricultural conditions had a lead-time of up to 2 months in, which has significant potential to enhance the early warning system for agriculture and food security.