Influence of climatic indices (AMO, PDO, and ENSO) and temperature on rainfall in the Northeast Region of India

This study explores the spatiotemporal rainfall variability in the Northeast region of India combined with an analysis of the effects of temperature and natural climatic indices [El-Nino Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and Atlantic Multi-decadal Oscillation (AMO)] on rainfall. The multi-timescale features of rainfall time series for periods 1871-2016 were analysed based on the continuous wavelet transform method. Cross-wavelet and wavelet coherence explore cross-correlation between temperature, natural climatic indices, and rainfall during 1950-2016. Results of the continuous wavelet transform revealed a significant cycle of 12 months on a monthly scale and 2-8-year period on an annual and seasonal scale. The cross-wavelet and wavelet coherence results showed that temperature affects rainfall only on intra-annual (0.5-1 years) scale. ENSO affects rainfall on both intra-annual (0.5-1 years) and inter-annual (1-10 years) scale. PDO affects rainfall on both inter-annual ( 1-10 years) and decadal (10-21 years) scale. AMO affects rainfall only on the decadal (10-21 years) scale. The result that comes out from this study is useful for climate change assessment, agriculture, and water resources management points of view of the Northeast region of India.