Tropical Atmospheric Variability forced by Oceanic Internal Variability

Markus Jochum

Atmospheric general circulation model experiments are conducted to quantify the contribution of internal oceanic variability in the form of tropical instability waves (TIWs) to interannual wind and rainfall variability in the tropical Pacific. It is found that in the central and eastern equatorial Pacific and near 25N and 25S TIWs force a significant increase in wind and rainfall variability from interseasonal to interannual time scales. Because of the stochastic nature of TIWs this means that climate models that do not take them into account will underestimate the strength and number of extreme events and may overestimate forecast capability.

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