Graphical Abstract

Seiki, A., S. Yokoi, and M. Katsumata, 2021: The impact of diurnal precipitation over Sumatra Island, Indonesia, on synoptic disturbances and its relation to the Madden-Julian Oscillation. J. Meteor. Soc. Japan, 99,
https://doi.org/10.2151/jmsj.2021-007
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Plain Language Summary: Upscale effects of diurnal precipitation over Sumatra on synoptic disturbances are examined. The strong diurnal cycle is followed by the development of synoptic disturbances over the eastern Indian Ocean for several days, and apparent twin synoptic disturbances straddling the equator develop only when the convective center of the Madden–Julian Oscillation (MJO) lies over the Indian Ocean. Furthermore, the MJO events with the strong diurnal cycle tend to have continuing eastward propagation of active convection across the Maritime Continent, suggesting that the strong diurnal cycle facilitate the smooth eastward propagation of the MJO.

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