Interaction between the MJO and High-Frequency Waves over the Maritime Continent in Boreal Winter
Interaction between the MJO and High-Frequency Waves over the Maritime Continent in Boreal Winter
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DOI：
10.1175/jcli-d-18-0511.1
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发表时间：
2019-06
影响因子：
4.9
通讯作者：
Yan Zhu;Tim Li;Ming Zhao;T. Nasuno
中科院分区：
文献类型：
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作者：
Yan Zhu;Tim Li;Ming Zhao;T. Nasuno
研究了1984-2005年冬季海洋大陆(MC)上空Madden-Julian振荡(MJO)与高频波(HFW)的双向相互作用。观测分析表明，在MJO活动期，水汽活动增强(减弱)在MJO对流的西(东)面和下方，而在MJO抑制相则相反。敏感度模型试验表明，MJO通过改变背景垂直风切变和比湿度来控制HFW活动。利用观测资料，研究了通过凝结加热和涡动量输送的非线性修正，从HFW到MJO的高层反馈。在MJO对流以东的低层，有相当大的(25%~40%)正加热异常()是由高频波的非线性整流贡献的。这种非线性修正主要归因于涡动经向水汽平流。动量收支诊断表明，850hPaMJO纬向风有60%是由于高频波与其他尺度气流的非线性相互作用造成的。其中，涡旋纬向动量通量辐散贡献最大。在MJO活动期，东(西)风垂直切变到MJO对流的西(东)面，导致高空纬向风异常的加强(减弱)。这导致MJO对流以东(西)涡动动量通量活动增加(减少)，从而在MJO活动(抑制)位相期间，在纬向风过渡区产生正(负)涡纬向动量通量辐散，有利于MJO向东传播。
The two-way interaction between Madden–Julian oscillation (MJO) and higher-frequency waves (HFW) over the Maritime Continent (MC) during boreal winter of 1984–2005 is investigated. It is noted from observational analysis that strengthened (weakened) HFW activity appears to the west (east) of and under MJO convection during the MJO active phase and the opposite is seen during the MJO suppressed phase. Sensitivity model experiments indicate that the control of HFW activity by MJO is through change of the background vertical wind shear and specific humidity. The upscale feedbacks from HFW to MJO through nonlinear rectification of condensational heating and eddy momentum transport are also investigated with observational data. A significantly large amount (25%–40%) of positive heating anomaly () at low levels to the east of MJO convection is contributed by nonlinear rectification of HFW. This nonlinear rectification is primarily attributed to eddy meridional moisture advection. A momentum budget diagnosis reveals that 60% of MJO zonal wind tendency at 850 hPa is attributed to the nonlinear interaction of HFW with other scale flows. Among them, the largest contribution arises from eddy zonal momentum flux divergence . Easterly (westerly) vertical shear to the west (east) of MJO convection during the MJO active phase causes the strengthening (weakening) of the HFW zonal wind anomaly. This leads to the increase (decrease) of eddy momentum flux activity to the east (west) of the MJO convection, which causes a positive (negative) eddy zonal momentum flux divergence in the zonal wind transitional region during the MJO active (suppressed) phase, favoring the eastward propagation of the MJO.