24STUDENT The IOD Impact on Asia and North Atlantic Oscillation: The Dependence on Phases and its Multi-Decadal Modulation

The Tropical Indian Ocean (TIO) precipitation anomalies play an important role in modulating climatic conditions over the West Asian and North Atlantic regions in boreal winter. Motivated by previous studies that suggest autumn Indian Ocean Dipole (IOD), rather than El Niño Southern Oscillation (ENSO), leads to strong Indian Ocean precipitation anomalies in early winter, we analyse IOD extra-tropical teleconnections and their different phases as well as multi-decadal modulation of their impacts. Our results suggest a strong connection between October IOD sea surface temperature (SST) anomalies and West Asian surface temperature in the DJF season, more specifically we see a significantly strong cold-wave response in West Asia in January, which moves toward southeast India and Bangladesh in February. The possible forcing mechanism behind this teleconnection is interpreted as a Rossby wave response in the South Asian region induced by the IOD which propagates into extra-tropical northern hemisphere and eventually impacts also the North Atlantic Osciallation (NAO). The response to different phases of the IOD and their multidecadal variations are investigated. Our results encourage the development of a statistical model inceasing the predictability of west Asian surface climate with a significant amount of lead-time.