Regional MJO Modulation of Northwest Pacific Tropical Cyclones Driven by Multiple Transient Controls
Regional MJO Modulation of Northwest Pacific Tropical Cyclones Driven by Multiple Transient Controls
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DOI：
10.1029/2020gl087148
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发表时间：
2020-06
影响因子：
5.2
通讯作者：
M. D. Fowler;Michael S. Pritchard
中科院分区：
文献类型：
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作者：
M. D. Fowler;Michael S. Pritchard
马登-朱利安振荡（MJO）因其对西北太平洋热带气旋（TC）的调制能力而被广泛认可，但对其基本机制的完整理解仍然不确定。除了MJO的相对湿度包络的既定影响之外，最近还通过新的成因潜力指数和高分辨率建模研究调用了其他动力学因素。在这里，我们重新审视了MJO通过由复合观测驱动的准显式气旋降尺度策略来调制西太平洋TC的能力，随后与成因指数配对以调查区域调制的驱动因素。我们揭示了两种不同的空间模式的TC调制中，MJO的动态和热力学效应的作用在串联，以增加TC。例如，在南中国海，与MJO的环流相关的切变减少导致在正湿度异常到来之前增加的潜在强度，所有这些联合收割机结合在一起，形成了一个长时间的气旋生成能力。
The Madden–Julian Oscillation (MJO) is widely acknowledged for its ability to modulate Northwest Pacific tropical cyclones (TCs), but a complete understanding of the underlying mechanisms remains uncertain. Beyond established effects of the MJO's relative humidity envelope, other dynamical factors have recently been invoked via new genesis potential indices and high‐resolution modeling studies. Here we revisit the ability of the MJO to modulate West Pacific TCs through a quasi‐explicit cyclone downscaling strategy driven by composited observations, paired later with a genesis index to investigate regional drivers of modulation. We reveal two distinct spatial modes of TC modulation in which the MJO's dynamic and thermodynamic effects act in tandem to increase TCs. In the South China Sea, for instance, shear reductions associated with the MJO's circulation lead to increasing potential intensity ahead of the arrival of a positive humidity anomaly, all of which combine for an extended period of cyclogenesis favorability.