Subseasonal Variability of ENSO-East Asia Teleconnections Driven by Tropical Convection Over the Indian Ocean and Maritime Continent

Abstract

The El Ni & ntilde;o-Southern Oscillation (ENSO) has a significant impact on the surface climate of East Asia by modulating the atmospheric circulation over the Kuroshio Extension. Here, we show that the ENSO-East Asia teleconnections are strongest in early winter due to the combined effects of the Indian Ocean and Maritime Continent convections, but weakest in mid-winter as these tropical convections weaken. During the early El Ni & ntilde;o winter, convection is enhanced over the Indian Ocean and suppressed over the Maritime Continent. The associated Rossby wave trains constructively interfere over the Kuroshio Extension, resulting in anticyclonic circulation anomalies. The equatorial central Pacific convection has a minimal impact on the East Asia. This result suggests that the Indian Ocean and the Maritime Continent convections, rather than the equatorial central Pacific convection, are the precursors of the early winter ENSO-East Asia teleconnections, and need to be considered for subseasonal-to-seasonal prediction in East Asia. The El Ni & ntilde;o-Southern Oscillation (ENSO) significantly influences the winter surface climate in East Asia through atmospheric teleconnections. The ENSO teleconnections are particularly pronounced in early winter when an anomalous anticyclonic circulation developes over the Kuroshio Extension and transports warm and moist air to the East Asian continent, but weaken in mid-winter. Here, we show that such subseasonal variability of the ENSO-East Asia teleconnections is primarily determined by tropical convection over the Indian Ocean and the Maritime Continent, with a minimal impact of convection over the equatorial central Pacific where ENSO develops. The El Ni & ntilde;o-Southern Oscillation (ENSO) teleconnections show distinct subseasonal variability over East Asia, with the strongest teleconnections in early winter The ENSO-East Asia teleconnections are modulated by anomalous tropical convection over the Indian Ocean and the Maritime Continent on subseasonal time scale Rossby wave trains induced by enhanced convection over the Indian Ocean and those by suppressed convection over the Maritime Continent constructively interfere over the East Asia during the early El Ni & ntilde;o winter