Premium
Modelling the influence of North Atlantic multidecadal warmth on the Indian summer rainfall
Author(s) -
Li Shuanglin,
Perlwitz Judith,
Quan Xiaowei,
Hoerling Martin P.
Publication year - 2008
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2007gl032901
Subject(s) - extratropical cyclone , atlantic multidecadal oscillation , climatology , trough (economics) , monsoon , thermohaline circulation , north atlantic oscillation , north atlantic deep water , atlantic equatorial mode , tropical atlantic , environmental science , oceanography , geology , tropical wave , sea surface temperature , tropical cyclone , economics , macroeconomics
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.