Thermospheric Composition O/N Response to an Altered Meridional Mean Circulation During Sudden Stratospheric Warmings Observed by GOLD

Abstract

Observations from the recently launched Global‐Scale Observations of the Limb and Disk (GOLD) instrument on the geostationary SES‐14 communications satellite reveal a substantial response of the mean state of the thermosphere to the Sudden Stratospheric Warming (SSW) event in early January 2019. The observed O/N 2 column density depletion of more than 10% starts at the onset of the SSW, maximizes at the time of the stratospheric wind reversal, and recovers toward the end of the SSW. A connection between SSW and thermospheric composition was previously predicted by model simulations but could not be observed before. The GOLD measurements support the scenario that enhanced global‐scale wave activity during SSWs causes an enhanced wave driving of the lower thermosphere zonal mean circulation that leads to a reduction in lower thermosphere atomic oxygen, which then propagates through molecular diffusion into the upper thermosphere.

Coupling From the Middle Atmosphere to the Exobase: Dynamical Disturbance Effects on Light Chemical Species

“…This enhanced poleward (and downward-not shown) flow driven at least in part by increased SW2 amplitudes between ∼115 and 150 km acts to adiabatically heat the lower thermosphere, especially at middle-to-high northern latitudes (see Figure 10). Further, this enhanced poleward (and downward) flow shown in Figure 8 coupled with enhanced equatorward (and upward) flow shown in Figure 6 between ∼90 and 110 km is consistent with previous modeling studies of enhanced lower atmospheric wave forcing on the meridional residual circulation (e.g., Miyoshi et al, 2015;Oberheide et al, 2020;Pedatella et al, 2016;Yamazaki & Richmond, 2013).…”

“…Ultimately, increased eastward small‐scale GWs dissipation/breaking during the January 2013 SSW/MC event appears to be the primary driver of light species depletions, with increased SW2 activity playing a modest role in the TIME‐GCM. With the recent launch of the Global‐scale Observations of the Limb and Disk (GOLD) mission studies using SABER H and GOLD O/N 2 (e.g., Oberheide et al, 2020) can be used to trace the effects of SSWs and MCs both vertically and horizontally within the atmosphere. These data provide the first opportunity to examine coupling from the high‐latitude stratosphere to the tropical thermosphere. Light species variability associated with SSW/MC may potentially affect the plasma population of the topside ionosphere and plasmasphere.…”

New Observations of Large‐Scale Waves Coupling With the Ionosphere Made by the GOLD Mission: Quasi‐16‐Day Wave Signatures in the F‐Region OI 135.6‐nm Nightglow During Sudden Stratospheric Warmings

“…This implies that the brightness depletion after day 25 (21 December 2018) may also be associated with the SSW. Pedatella et al (2016) suggested that an enhanced migrating semidiurnal tide (SW2) during SSW events is able to induce a global‐scale upward circulation and thereby a reduction of zonal mean O/N 2 ratio and electron densities (Liu & Roble, 2002; Oberheide et al, 2020; Shepherd et al, 1999). In addition, the intraseasonal variability (e.g., Sassi et al, 2019; Vergados et al, 2018) in the lower atmosphere could be responsible for the observed 60‐day oscillation in brightness as well.…”

Longitudinally Dependent Low‐Latitude Ionospheric Disturbances Linked to the Antarctic Sudden Stratospheric Warming of September 2019

“…The second temporal scale is associated with ionospheric oscillations with planetary wave time scales and observed as 2‐, 5‐ to 6‐, or 10‐ to 16‐day quasi‐periodic variations in peak electron density, peak height of the F region, and locations of the equatorial ionization anomaly (EIA) (Mo et al, 2014; Patra et al, 2014). The third temporal scale can last for 10–20 days or longer and is expressed as decreases in zonal and diurnal mean electron density and mean ionospheric peak height (Pancheva & Mukhtarov, 2011), decrease in thermospheric density (Liu et al, 2011; Yamazaki et al, 2015), and decrease in thermospheric O/N 2 ratio (Oberheide et al, 2020). These observational studies have stimulated considerable advances in understanding the physical mechanisms that link the state of the stratosphere to low‐latitude ionospheric variability.…”

“…These observational studies have stimulated considerable advances in understanding the physical mechanisms that link the state of the stratosphere to low‐latitude ionospheric variability. Three generally accepted mechanisms include (1) changes in the migrating and non‐migrating solar and lunar tides (Forbes & Zhang, 2012; Jin et al, 2012; Liu et al, 2010; Pedatella & Forbes, 2010), (2) increases in stratospheric tropical ozone during SSWs that lead to an enhancement in the migrating tide (Goncharenko et al, 2012; Limpasuvan et al, 2016; Siddiqui et al, 2019), and (3) reductions in the thermospheric O/N 2 ratio due to tidal dissipation (Oberheide et al, 2020; Yamazaki & Richmond, 2013). Superposition of these and other mechanisms that are still yet to be discovered creates highly variable conditions in the quiet‐time ionosphere‐thermosphere system that can be observed in multiple upper atmospheric parameters.…”