Modeling Evidence of QBO‐MJO Connection: A Case Study

Abstract

The boreal winter Madden-Julian Oscillation (MJO) is modulated by the Quasi-Biennial Oscillation (QBO). The MJO becomes relatively strong during the easterly QBO (EQBO) winters but weak during the westerly QBO (WQBO) winters. To better understand their relationship, a set of WRF model experiments is conducted with varying lateral boundary conditions. The MJO event in December 2007, during EQBO winter, is chosen as a reference case. The control experiment qualitatively reproduces the observed MJO. When the lateral boundary conditions are switched with those of WQBO or strong WQBO winters, the MJO becomes weak over the Maritime Continent. All eight ensemble members exhibit enhanced outgoing longwave radiation and reduced precipitation from EQBO to WQBO, and to strong WQBO conditions, although the magnitude of changes is smaller than observations. This result, one of the first mesoscale modeling evidences of the QBO-MJO connection, suggests that the MJO is at least partly modulated by the QBO.

Global Responses of Gravity Waves and Zonal Mean Winds to the Madden‐Julian Oscillation and the Latitudinal Dependence of Their Relations Using MERRA‐2

“…First, the zonal wind anomalies in the tropics show multiple changes of signs with altitude, which are very similar to the QBO signals in the zonal mean winds and may indicate that the mechanism of the MJO modulation of winds is similar to the QBO, which involves wave‐mean interactions, i.e., the wind filters the propagation of GWs, and the momentum deposited by GWs in turn drives the wind (Baldwin et al., 2001). In fact, the interactions among QBO, GWs and MJO are complicated and have drawn significant interests recently (e.g., Back et al., 2020; Feng & Lin, 2019; Martin et al., 2021; Nishimoto & Yoden, 2017). Second, the zonal wind anomalies change signs a few times with latitude below 20 km at middle and low latitudes, which may be related to the MJO modulation of the wind associated with the Hadley and Ferrell cells.…”

On the response of the middle atmosphere to anthropogenic forcing

“…Understanding the processes that drive the QBO and are responsible for its variability is important not just for its own sake but also for assessing the influence of the QBO in the transport of chemical species, the interpretation of apparent changes in the strength of the BDC, and the tele-connections to the extratropical stratosphere and troposphere. [109][110][111][112][113][114][115]…”

The Influence of the Stratospheric Quasi‐Biennial Oscillation on the Tropical Easterly Jet Over the Maritime Continent

“…QBO is driven by tropical atmospheric disturbances such as Kelvin waves, Rossby‐gravity waves, small‐scale gravity waves, and Inertia‐gravity waves with periods much shorter than QBO (Baldwin et al., 2001; Dunkerton, 1997; Kang & Chun, 2021; Plumb, 1977). There are many studies on the effects of QBO on the tropical tropospheric weather systems, for example, Madden‐Julian oscillation (MJO) (Back et al., 2020; Martin et al., 2021; Son et al., 2017), the boreal summer monsoon (Giorgetta et al., 1999; Rai & Dimri, 2017), and tropical deep convection (Liess & Geller, 2012; Nie & Sobel, 2015). Hitchman et al.…”

“…small-scale gravity waves, and Inertia-gravity waves with periods much shorter than QBO (Baldwin et al, 2001;Dunkerton, 1997;Kang & Chun, 2021;Plumb, 1977). There are many studies on the effects of QBO on the tropical tropospheric weather systems, for example, Madden-Julian oscillation (MJO) (Back et al, 2020;Martin et al, 2021;Son et al, 2017), the boreal summer monsoon (Giorgetta et al, 1999;Rai & Dimri, 2017), and tropical deep convection (Liess & Geller, 2012;Nie & Sobel, 2015). Hitchman et al (2021) reviewed the observational history of the influence of QBO on the tropical and subtropical circulation in the upper troposphere and lower stratosphere.…”