How Important Are Horizontal Eddy Moisture Transports for the MJO's Eastward Propagation?
How Important Are Horizontal Eddy Moisture Transports for the MJO's Eastward Propagation?
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DOI：
10.1029/2023gl103944
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发表时间：
2023-06
影响因子：
5.2
通讯作者：
S. Tulich
中科院分区：
文献类型：
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作者：
S. Tulich
众所周知，马登-朱利安振荡（MJO）的东向传播关键取决于水平水汽平流的影响，这涉及两种主要类型的环流异常。第一个是MJO本身的那些，而第二个是嵌入式Rossby型“涡旋”的那些，这些涡旋往往在MJO对流中心以西最活跃。为了量化涡旋的相对重要性，采用了一种新的方法，其中它们的正式定义是由观测到的二元MJO指数的最小二乘拟合的残差给出的。结果表明，以这种方式定义的涡，通常是主要的重要性，促进MJO的东传播方面的列集成水分。然而，当使用传统的基于滤波器的方法来定义涡流时，情况会发生逆转，这些涡流在本质上是严格的“高频”。
The eastward propagation of the Madden‐Julian oscillation (MJO) is known to hinge crucially on the effects of horizontal moisture advection, which involve two main types of circulation anomalies. The first are those of the MJO itself, while the second are those of embedded Rossby‐type “eddies,” which tend to be most active to the west of the MJO's convective center. To quantify the relative importance of the eddies, a novel approach is taken in which their formal definition is given by the residual of a least‐squares fit to an observed bivariate MJO index. Results show that the eddies, when defined in this way, are generally of leading importance for fostering the MJO's eastward propagation in terms of column‐integrated moisture. The picture is seen to be reversed, however, when using a traditional filter‐based method to define the eddies, which are then strictly “high‐frequency” in nature.