Stratospheric Influences on the MJO-Induced Rossby Wave Train: Effects on Intraseasonal Climate
Stratospheric Influences on the MJO-Induced Rossby Wave Train: Effects on Intraseasonal Climate
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DOI：
10.1175/jcli-d-18-0811.1
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发表时间：
2020-01
影响因子：
4.9
通讯作者：
L. Hood;M. Redman;W. Johnson;Thomas J. Galarneau
中科院分区：
文献类型：
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作者：
L. Hood;M. Redman;W. Johnson;Thomas J. Galarneau
热带马登-朱利安振荡 (MJO) 激发了向北传播的罗斯贝波列，这在很大程度上决定了 MJO 的温带表面天气后果。先前的工作已经证明了对流层厄尔尼诺南方涛动（ENSO）对该波列特征的显着影响。在这里，对北方冬季延长期间的 ERA-中期海平面压力 (SLP) 和地表气温 (SAT) 数据进行了综合分析，以研究平流层强迫 [准两年一次振荡 (QBO) 和 11 年太阳活动周期] 在修改波列及其后果方面的额外作用。两个 QBO 相位的 20-100 天滤波数据的 MJO 相位组合表明，与 ENSO 的冷相位类似，QBO 的东相位 (QBOE) 会产生更强的波列以及相关的 SLP 和 SAT 异常调制。特别是，在 MJO 阶段 5-7 期间，相对于 QBO 西风阶段 (QBOW)，QBOE 期间北大西洋/欧亚扇区的正 SLP 和负 SAT 异常增强。相反的情况发生在最早的 MJO 阶段。 QBOE 期间北美东部的 SAT 异常也受到更强烈的调节。尽管由于数据记录较短而不太确定，但有一些证据表明太阳周期的最小相位 (SMIN) 会产生类似的 SLP 和 SAT 异常调制。当两个或多个强迫叠加时（例如 QBOE/冷 ENSO、SMIN/QBOE 等），会产生最强的 SLP 和 SAT 异常调制。
The tropical Madden–Julian oscillation (MJO) excites a northward propagating Rossby wave train that largely determines the extratropical surface weather consequences of the MJO. Previous work has demonstrated a significant influence of the tropospheric El Niño–Southern Oscillation (ENSO) on the characteristics of this wave train. Here, composite analyses of ERA-Interim sea level pressure (SLP) and surface air temperature (SAT) data during the extended northern winter season are performed to investigate the additional role of stratospheric forcings [the quasi-biennial oscillation (QBO) and the 11-yr solar cycle] in modifying the wave train and its consequences. MJO phase composites of 20–100-day filtered data for the two QBO phases show that, similar to the cool phase of ENSO, the easterly phase of the QBO (QBOE) produces a stronger wave train and associated modulation of SLP and SAT anomalies. In particular, during MJO phases 5–7, positive SLP and negative SAT anomalies in the North Atlantic/Eurasian sector are enhanced during QBOE relative to the westerly phase of the QBO (QBOW). The opposite occurs during the earliest MJO phases. SAT anomalies over eastern North America are also more strongly modulated during QBOE. Although less certain because of the short data record, there is some evidence that the minimum phase of the solar cycle (SMIN) produces a similar increased modulation of SLP and SAT anomalies. The strongest modulations of SLP and SAT anomalies are produced when two or more of the forcings are superposed (e.g., QBOE/cool ENSO, SMIN/QBOE, etc.).