On the weakening relationship between the indian monsoon and ENSO
Analysis of the 140-year historical record suggests that the inverse relationship between the El Nino-Southern Oscillation (ENSO) and the Indian summer monsoon (weak monsoon arising from warm ENSO event) has broken down in recent decades. Two possible reasons emerge from the analyses. A southeastward shift in the Walker circulation anomalies associated with ENSO events may lead to a reduced subsidence over the Indian region, thus favoring normal monsoon conditions. Additionally, increased surface temperatures over Eurasia in winter and spring, which are a part of the midlatitude continental warming trend, may favor the enhanced land-ocean thermal gradient conducive to a strong monsoon. These observations raise the possibility that the Eurasian warming in recent decades helps to sustain the monsoon rainfall at a normal level despite strong ENSO events.
Kumar
KK
International Research Institute (IRI) for Climate Prediction, Lamont-Doherty Earth Observatory (LDEO) of Columbia University, Post Office Box 1000, Route 9W, Palisades, NY 10964-8000, USA. LDEO of Columbia University, Post Office Box 1000, Rou.
Rajagopalan
B
Cane
MA