Does the Madden‐Julian Oscillation modulate stratospheric gravity waves?

Abstract

The circulation of the stratosphere is strongly influenced by the fluxes of gravity waves propagating from tropospheric sources. In the tropics, these gravity waves are primarily generated by convection. The Madden‐Julian Oscillation (MJO) dominates the intraseasonal variability of this convection. However, the influence of the MJO on the variability of stratospheric gravity waves is largely unknown. Here we examine gravity wave potential energy at 26 km and the upper tropospheric zonal wind anomaly of the MJO at 200 hPa, sorted by the relative phase of the MJO using the Real Multivariate MJO indices. We show that a strong anticorrelation exists between gravity wave potential energy and the MJO eastward wind anomaly. We propose that this correlation is a result of the filtering of upward propagating waves by the MJO winds. The study provides the first observational evidence that the MJO contributes significantly to the global variability of stratospheric gravity waves in the tropics.

The Effect of the Madden‐Julian Oscillation on the Mesospheric Migrating Diurnal Tide: A Study Using SD‐WACCM

“…Intraseasonal variability in the equatorial mesosphere has also been reported by Liebermann (1998), Pancheva et al (2003), Sridharan et al (2007), and Guharay et al (2012). Since the ISO seen in the MLT region has a similar period to the MJO, a possible relation between these ISO variations has been suggested (Eckermann et al, 1997;Moss et al, 2016;Yang et al, 2017). As suggested by Garcia (2000), Isoda et al (2004), and Kumar et al (2007), MJO-related convective anomalies are considered to be related to the ISO variabilities in nonmigrating tides.…”

“…Eckermann and Vincent (1994) first reported ISO of the zonal wind in the equatorial MLT from medium-frequency radar observations. Since the ISO seen in the MLT region has a similar period to the MJO, a possible relation between these ISO variations has been suggested (Eckermann et al, 1997;Moss et al, 2016;Yang et al, 2017). Since the ISO seen in the MLT region has a similar period to the MJO, a possible relation between these ISO variations has been suggested (Eckermann et al, 1997;Moss et al, 2016;Yang et al, 2017).…”

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

“…The Madden-Julian oscillation (MJO) is the dominant mode of the tropospheric intraseasonal oscillation (ISO) and is characterized by repeated eastward-propagating deep convection and coupled circulation (Madden & Julian, 1971, 1972, with a period of~30-80 days (e.g., Zhang, 2005). As suggested in previous studies, MJO events interact with tropospheric phenomena such as El Niño-Southern Oscillation (ENSO) and monsoons Waliser et al, 2003) and affect anomalous planetary waves (PWs) and gravity wave activities (Gill, 1980;Moss et al, 2016;Schwartz et al, 2008;Zagar & Franzke, 2015). MJO-induced adiabatic heating in the tropics could excite PWs in the middle and high latitudes (Ferranti et al, 1990;Seo & Son, 2012), which would affect the variations in the Northern Annual Mode (Cassou, 2008;Lin et al, 2009).…”

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

“…Eckermann et al (1997) reported MJO-like oscillations in the equatorial MLT winds and suggested that they are modulated by GWs and tides excited by tropical convection which has MJO signals. More recently, Moss et al (2016) used observations from the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellite and found a strong anticorrelation between the GW potential energy at 26 km and the MJO eastward wind anomaly. They suggested that this anticorrelation results from the filtering of GWs by the MJO winds.…”