Investigating the Atlantic-Indian summer monsoon multidecadal teleconnections in the PMIP3/CMIP5 Last Millennium simulations

Understanding the natural variability of Indian summer monsoon (ISM) is a crucial aspect relevant for decadal climate predictions and climate change studies. The multidecadal variability of ISM is known to have a close association with the Atlantic multidecadal oscillations (AMO). Several teleconnection pathways have been suggested to explain the co-variability of the AMO and ISM in multidecadal timescales. One hypothesis is that the AMO modulates the interannual North Atlantic Oscillation (NAO) mode and there by influences the monsoon via Eurasian temperature modulations. Direct atmospheric teleconnection, across Eurasia, through upper-level circulation anomalies has also been attributed to the observed AMO-ISM relationship. Another possibility is the AMO modulating the monsoon via the Pacific pathway through the atmospheric bridge mechanism and associated modulations of the Hadley-Walker circulations. The Last millennium (LM) (851-1848) climate simulations part of the PMIP3/CMIP5 gives an opportunity to better understand the fidelity of climate models in capturing the AMO-ISM teleconnection mechanisms. In this study we explore how well the proposed mechanisms are represented in eight global climate models (GCM) LM simulations. Such a study, assessing the validity of different AMO-monsoon teleconnection mechanisms in different model climates provides crucial information about how reliable the respective GCMs may be in making decadal climate predictions.