Thermospheric composition response to Sudden Stratospheric Warmings observed by the Global-Scale Observations of the Limb and Disk (GOLD) instrument

Abstract

<p>Observations from the recently launched Global-Scale Observations of the Limb and Disk (GOLD) instrument on the geostationary SES-14 communications satellite provide the first observational proof for the impact of stratospheric weather, that is, polar vortex dynamics during a Sudden Stratospheric Warming (SSW), on the composition of the thermosphere. During the early January 2019 SSW, GOLD observes a >10% O/N2 column density ratio depletion in both hemispheres unrelated to geomagnetic activity. The data and supporting TIE-GCM and WACCM-X simulations show that enhanced global-scale wave activity during the SSW 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. The observed composition changes will likely impact Earth's ionospheric plasma environment as well and imply another pathway for SSW impacts on space weather, in addition to dynamo processes.</p>