ENSO and All-India Rainfall

This plot shows the relationship between summer monsoonal rainfall in India and ENSO.

As researched by Gilbert Walker in the late 1800's, the appearance of drought in India is connected to shifts in ENSO. The plot indicates that ENSO has a profound impact on summer monsoonal rainfall across India as most major droughts are shown to occur during El Niño events. Conversely, above average rainfall is shown to occur during La Niña events.

The heights of the bars on the plot give the relative strength of the rainfall in the India monsoon: up means greater than normal, down is a drought. The rainfall data used are anomalies of the June-September mean from the All-India rainfall index, using the entire 1856-2004 as the base period. The colors of the bars give the strength of ENSO during October-January for that year: red is a warm (El Niño) event, blue is a cold (La Niña) event, and off-white indicates near-normal sea-surface temperatures in the east-central equatorial Pacific Ocean (the NINO3 region ).

Dataset Documentation

Precipitation Data

All-India Rainfall Index from 1856 to 2004
Data Source
The Indian Institute of Tropical Meteorology (IITM) (All-India Rainfall)
Time series June-September mean of rainfall across India

SST Data

Kaplan Extended Version 2 monthly sea surface anomalies from 1856 to 2004
Data Source
Lamont-Doherty Earth Observatory, IRI Data Library (Kaplan Extended)
October-January seasonal-average NINO3 SST index calculated from the Kaplan Extended Version 2 monthly sea surface temperature anomalies


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