Role of the Maritime Continent in the remote influence of Atlantic Niño on the Pacific

Atlantic Nino, the dominant climate mode in the equatorial Atlantic, is known to remotely force a La Nina-like response in the Pacific, potentially affecting seasonal climate predictions. Here, we use both observations and large-ensemble simulations to explore the physical mechanisms linking the Atlantic to the Pacific. Results indicate that an eastward propagating atmospheric Kelvin wave from the Atlantic, through the Indian Ocean, to the Pacific is the primary pathway. Interaction of this Kelvin wave with the orography of the Maritime Continent induces orographic moisture convergence, contributing to the generation of a local Walker Cell over the Maritime Continent-Western Pacific area. Moreover, land friction over the Maritime Continent dissipates Kelvin wave energy, affecting the strength of the Bjerknes feedback and thus the development of the La Nina-like response. Therefore, improving the representation of land-atmosphere-ocean interactions over the Maritime Continent may be fundamental to realistically simulate Atlantic Nino's impact on El Nino-Southern Oscillation.