Response of the Northern Stratosphere to the Madden‐Julian Oscillation During Boreal Winter

Abstract

In this study, the effects of the Madden‐Julian oscillation (MJO) on the northern stratosphere during boreal winter are investigated, especially in cases with the absence of a stratospheric sudden warming (SSW) event. During the wintertime, the polar cap temperature is expected to increase following MJO phase 2 (P2), P3, P4, and P7. However, the responses after P2 and P3 are much weaker if the dates from 50 days before to 50 days after the SSW central days are excluded from the composite. This result implies that the stratospheric polar warming following MJO P2 and P3 is sensitive to the occurrence of SSWs. After excluding the SSW events from the composite, the subsequent temperature anomalies strengthen and become more significant approximately 30 days after MJO P4 and 10 days after MJO P7. Planetary wave (PW) anomalies are enhanced in the midlatitudes of the upper troposphere, lagging MJO P4 by 15–25 days and lagging MJO P7 by 5–15 days. Thus, the upward propagation and dissipation of PWs in the stratosphere are significantly enhanced, further strengthening the Brewer‐Dobson circulation in the Northern Hemisphere stratosphere. The WN1, which is induced by the MJO in the stratosphere, is the dominant component of PW perturbation. The enhanced PW dissipation in the high latitudes of the stratosphere is weaker in terms of lagging MJO P4, so the zonal wind and temperature anomalies after MJO P4 are less significant in the polar region, especially in the lower stratosphere.

Modulation by ENSO of the Relationship Between Stratospheric Sudden Warming and the Madden‐Julian Oscillation

“…Significant warming also occurs after phases 4 and 5, which was not shown in G12. The results are similar to those of Yang et al (2019). The differences with the findings of G12 are probably due to the different choice of data sets, time period, and definitions of MJO events in this study.…”

“…(hereafter G12) found that midwinter SSW tends to follow certain MJO phases, which is due to the influence of the MJO on the North Pacific region that is strongly associated with tropospheric planetary waves. Previous studies both from reanalysis data and model simulations have confirmed a robust MJO-vortex connection and suggest an enhanced stratospheric heat flux related to the MJO (Garfinkel et al, 2014;Kang & Tziperman, 2017;Wang et al, 2018;Yang et al, 2019). Liu et al (2014) (hereafter L14) analyzed different MJO-SSW relationships for different types of SSW (i.e., vortex-displacement and vortex-split).…”

Comprehensive Study of the Climatology of the Quasi‐6‐Day Wave in the MLT Region Based on Aura/MLS Observations and SD‐WACCM‐X Simulations

“…The MJO is the dominant mode of the tropospheric intraseasonal oscillation (ISO) (R. A. Madden & Julian, 1971, 1972b), and also has a considerable impact on tropospheric and middle atmospheric circulation and other dynamical processes. The tropical adiabatic heating induced by the MJO can enhance the quasi‐stationary wave activity in middle and high latitudes (Seo & Son, 2012; Yang et al., 2019). Therefore, major SSWs during Northern Hemisphere wintertime are also related to certain phases of the MJO (Garfinkel et al., 2014; Garfinkel, Feldstein, et al., 2012).…”

SABER Observations of Gravity Wave Responses to the Madden‐Julian Oscillation From the Stratosphere to the Lower Thermosphere in Tropics and Extratropics

“…Many studies have shown that the MJO has a substantial impact on the extratropical circulation through the excitation of poleward propagating Rossby waves (e.g., Higgins & Mo, 1997; L'Heureux & Higgins, 2008; Lukens et al, 2017). Multiple studies have shown that MJO modulates the stratospheric polar vortex (Feng & Lin, 2019; Garfinkel et al, 2014; Garfinkel & Schwartz, 2017; Yang et al, 2019) and the occurrence frequency of sudden stratospheric warmings (SSWs) in the NH (Garfinkel et al, 2012; Liu et al, 2014; Wang et al, 2018). Garfinkel et al (2012) found that following MJO P3 (P7) a weakened (strengthened) polar vortex was found in the NH.…”