Kelvin and Rossby Wave Contributions to the Mechanisms of the Madden–Julian Oscillation
Kelvin and Rossby Wave Contributions to the Mechanisms of the Madden–Julian Oscillation
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DOI：
10.3390/geosciences12090314
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发表时间：
2022-08
期刊：
影响因子：
2.7
通讯作者：
P. Haertel
中科院分区：
文献类型：
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作者：
P. Haertel
马登-朱利安涛动（MJO）是一个大尺度的热带天气系统，在赤道印度洋和西太平洋上空产生强降雨，周期为40-50天。它的环流向东传播到整个世界，并影响热带气旋的形成、季风爆发和中纬度洪水。这项研究探讨了拉格朗日大气模式（LAM），这已被证明是准确地模拟MJO的MJO的机制，并预测MJO环流将加强海洋变暖。LAM MJO的第一个斜压环流被投射到开尔文波上，留下一个非常类似于Rossby波的残差。每种波类型的贡献水分和湿焓预算进行评估。而垂直平流的水分的开尔文波占大部分的MJO的降水，这波也出口了大量的干静态能量，使总的来说，它减少了列集成湿焓在强降水期间。相比之下，罗斯贝波的水平环流在最强烈的对流之前积累了水分，其表面风扰动增强了MJO对流中心附近的蒸发。与开尔文波相关的表面通量有助于维持MJO对流活跃区域之外的环流。
The Madden–Julian Oscillation (MJO) is a large-scale tropical weather system that generates heavy rainfall over the equatorial Indian and western Pacific Oceans on a 40–50 day cycle. Its circulation propagates eastward around the entire world and impacts tropical cyclone genesis, monsoon onset, and mid-latitude flooding. This study examines the mechanism of the MJO in the Lagrangian atmospheric model (LAM), which has been shown to simulate the MJO accurately, and which predicts that MJO circulations will intensify as oceans warm. The LAM MJO’s first baroclinic circulation is projected onto a Kelvin wave leaving a residual that closely resembles a Rossby wave. The contribution of each wave type to moisture and moist enthalpy budgets is assessed. While the vertical advection of moisture by the Kelvin wave accounts for most of the MJO’s precipitation, this wave also exports a large amount of dry static energy, so that in total, it reduces the column integrated moist enthalpy during periods of heavy precipitation. In contrast, the Rossby wave’s horizontal circulation builds up moisture prior to the most intense convection, and its surface wind perturbations enhance evaporation near the center of MJO convection. Surface fluxes associated with the Kelvin wave help to maintain its circulation outside of the MJO’s convectively active region.