ENSO-Monsoon Relationship in a 1000-yr MRI-CGCM Simulation
A. Kitoh (1)
(1) Meteorological Research Institute
The interannual variability of the Indian summer monsoon rainfall and its close relation with
ENSO is known (drought conditions over India accompany warm ENSO events and vice versa),
but recent observation suggests a weakening of this ENSO-monsoon relationship and a
possible link to global warming is suggested. Here we analyze ENSO-monsoon relationship in
a 1000-year control simulation of the MRI coupled GCM (MRI-CGCM2.2, T42L30). An overall
correlation between the JJA Nino3.4 SST and the JJA Indian monsoon rainfall is -0.39 with
reasonable circulation characteristics associated with model ENSO. Simulated ENSO-monsoon
relationship reveals long-term variations from -0.71 to +0.07 in moving 31-year windows.
The poor-correlation periods coincide with periods when the Indian monsoon rainfall is
above the long-term average, SST is warmer over the eastern Indian Ocean and the western
Pacific, and convection center is located more westward. It is suggested that the magnitude
of mean monsoon rainfall is more important than that of Nino3.4 SST on ENSO-monsoon
relationship.