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The ENSO-Monsoon Relationship: The Role of the Indonesian Throughflow

OCCI Funded Project: 2006

Proposed Research

The tropical Pacific and Indian Ocean are the largest centers of convective activity of the planet and their interaction is likely to be important in determining tropical climate variability over a wide range of timescales. Various mechanisms of atmospheric teleconnection between the Indian and the Pacific basin have been investigated. Yet the weakening of the relationship between the El Nino Southern Oscillation and the Indian monsoon rainfall during the last two decades of the XX century came as a surprise. Supported by the analysis of data assimilation products (see Figure below), we hypothesize that the relationship between the South Asia monsoon and the tropical Pacific implies also an oceanic bridge, modulated by the variability of the thermocline in the West Pacific and at the Indonesian Throughflow. The goal of this work is to test such a hypothesis, using a high resolution general circulation ocean model to investigate if and how thermocline anomalies associated with ENSO can precondition the ocean subsurface in the eastern Indian Ocean, favoring the co-occurrence of the same phase of ENSO and of the Indian Ocean Zonal Mode, and therefore intensifying the South Asian monsoon.

Originally published: January 1, 2006