Unraveling the Mystery of Indian Monsoon Failure During El Niño

Abstract

The 132-year historical rainfall record reveals that severe droughts in India have always been accompanied by El Niño events. Yet El Niño events have not always produced severe droughts. We show that El Niño events with the warmest sea surface temperature (SST) anomalies in the central equatorial Pacific are more effective in focusing drought-producing subsidence over India than events with the warmest SSTs in the eastern equatorial Pacific. The physical basis for such different impacts is established using atmospheric general circulation model experiments forced with idealized tropical Pacific warmings. These findings have important implications for Indian monsoon forecasting.

Changes in the large‐scale features associated with the Indian summer monsoon in the recent decades

“…In addition, negative anomaly of less than −0.4°C observed over the NW Indian Ocean is due to cross-equatorial flow. In Case-II, weak negative and positive SST anomaly over central and eastern equatorial Pacific, respectively is observed, such type of SST gradient relationship with ISM is documented by Krishna Kumar et al, 2006. Weak signal of IOD events (Saji et al, 1999) with positive (negative) SST anomalies over the west (east) Indian Ocean is evident in the equatorial Indian Ocean.…”

The resolution sensitivity of the South Asian monsoon and Indo-Pacific in a global 0.35° AGCM

“…Webster and Yang 1992;Kumar et al 2006). Coupling to a dynamical ocean is required to accurately simulate the teleconnection between ENSO and the monsoon domain (Bracco et al 2005;), but the relationship between prescribed Pacific SSTs and the South Asian monsoon may still change as resolution is increased in the AGCM.…”

Decadal to multi-decadal scale variability of Indian summer monsoon rainfall in the coupled ocean-atmosphere-chemistry climate model SOCOL-MPIOM

“…Ample rainfall occurs over the Indian region during the years when Niño3 anomalies are <−1 and ISMR anomalies are >+1, whereas dry events occur when Niño3 anomalies are >1 and ISMR anomalies are <−1 (red dots in Fig. 7a-g) (Kumar et al 2006). The simulated correlation coefficients (L1:−0.49; L2: −0.26; M1: −0.43; M2: −0.49) reasonably coincide with the observed relationship (20CR-Precip: −0.28, GPCC: −0.60, IITM-Precip: −0.59) between Niño3 and ISMR.…”