文章基本信息

标题：CINDY2011/DYNAMO Madden-Julian oscillation successfully reproduced in global cloud/cloud-system resolving simulations despite weak tropical wavelet power
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作者：Tomoki Miyakawa ; Kazuyoshi Kikuchi
期刊名称：Scientific Reports
电子版ISSN：2045-2322
出版年度：2018
卷号：8
期号：1
页码：11664
DOI：10.1038/s41598-018-29931-4
语种：English
出版社：Springer Nature
摘要：The role of tropical atmospheric waves in the propagation mechanism of the Madden-Julian oscillation (MJO), a huge eastward-propagating atmospheric pulse that dominates intraseasonal variation of the tropics and affects the entire globe, has been long discussed but remains unclear. An MJO event observed in a major field campaign is reproduced using a front-running global cloud/cloud-system resolving model with 3.5 km, 7 km, and 14 km meshes. The eastward-migration speed of the MJO convective envelope in the 3.5 km and 14 km simulations agree well with observation, despite weak Kelvin wave signal power calculated by applying a combined Fourier-wavelet transform method. Our results suggest that the eastward propagation of this MJO event was principally controlled by an MJO-scale energy balance, and not by dynamical interaction of embedded tropical waves. The eastward propagation is delayed in the 7 km simulation, which features the highest surface latent heat flux to the west of the convective envelope center. This latent heat flux appears to be caused by prolonged existence of westward-migrating Rossby wave-like cyclonic disturbances near the equator; the embedded waves may not be part of the essential mechanism for the MJO eastward propagation, but can affect it by altering the energy balance.