The connection between the Atlantic Multidecadal Oscillation and the Indian Summer Monsoon in Bergen Climate Model Version 2.0

A pre-industrial multicentury simulation with Bergen Climate Model Version 2 (BCM in brief) is used to investigate the linkage between the Atlantic Multidecadal Oscillation (AMO) and the Indian Summer Monsoon (ISM). The results suggest that the model reproduces the general characters of the observed linkage between AMO and ISM, and that a positive AMO favors more rainfall over India from July to October. The ISM is intensified and the seasonal withdrawal of ISM delayed with one month, in agreement with previous observational and model's results. Further diagnoses indicate that this impact is achieved through an atmospheric teleconnection pattern. A propagating Rossby wave train from the North Atlantic across South Asia leads to enhanced South Asia high and consequently a strengthening of the ISM.