Modelling the influence of North Atlantic multidecadal warmth on the Indian summer rainfall
Article first published online: 5 MAR 2008
Copyright 2008 by the American Geophysical Union.
Geophysical Research Letters
Volume 35, Issue 5, March 2008
How to Cite
2008), Modelling the influence of North Atlantic multidecadal warmth on the Indian summer rainfall, Geophys. Res. Lett., 35, L05804, doi:10.1029/2007GL032901., , , and (
- Issue published online: 5 MAR 2008
- Article first published online: 5 MAR 2008
- Manuscript Accepted: 30 JAN 2008
- Manuscript Revised: 14 JAN 2008
- Manuscript Received: 5 DEC 2007
- Atlantic Multidecadal Oscillation;
- Indian summer rainfall;
 Ensemble experiments with an atmospheric general circulation model reveal that a positive (warm) ocean phase of the Atlantic Multidecadal Oscillation (AMO) increases Indian summer rainfall. The intensification is driven by extratropical North Atlantic warmth, with some cancellation associated with monsoon weakening in response to tropical North Atlantic warmth. Mechanistically, warm extratropical North Atlantic SSTs increase local rainfall, inducing an arching extratropical wavetrain response. The latter leads to intensified northern subsidence of monsoon mean meridional streamflow as well as widespread low surface pressure over North Africa, the Middle East and the western Indian Ocean contributing to a strengthened Indian monsoon trough and increased monsoon rainfall. Warm tropical North Atlantic SSTs primarily increase local tropical Atlantic rainfall that induces a tropically-confined response consisting of low level easterly wind anomalies over the Indian Ocean and dynamically induced subsident drying over India.