Coupled interactions of the monsoons

A case is made to show that all continental summer monsoon regions of the globe are manifestations of strong, coupled ocean-land-atmosphere interactions. It is shown from observations that the auto-decorrelation time of the daily rainfall in the summer monsoon regions is usually in excess of 3 days. This characteristic feature of the monsoon rainfall is well simulated in a global coupled ocean-land-atmosphere model. The atmospheric general circulation model component integrations of the same coupled model forced with observed SST show a distinctly shorter auto-decorrelation time of the daily monsoon precipitation. An obvious conclusion is that air-sea coupling is essential for this feature of the monsoon rainfall to be simulated. But through additional diagnostic calculations it is also shown that the robust land-atmosphere interactions over these regions also contribute to the lengthening of the auto-decorrelation time of the daily continental summer monsoon rainfall.