Gravity Wave Activity During the 2024 Sudden Stratospheric Warmings Observed by Atmospheric Waves Experiment (AWE)

Abstract

The National Aeronautics and Space Administration (NASA) Atmospheric Waves Experiment (AWE) instrument, launched in November 2023, provides direct observation of small-scale (30–300 km) gravity waves (GWs) in the mesosphere on a global scale. This work examined changes in GW activity observed by AWE during two major Sudden Stratospheric Warmings (SSWs) in the 2023 and 2024 winter season. Northern Hemisphere (NH) midlatitude GW activity during these events shared similarities. Variations in mesospheric GW activity showed an evident correlation with the magnitude of zonal wind in the upper stratosphere. NH midlatitude GW activity at (Formula presented.) 87 km was reduced following the onset of SSWs, likely caused by wind filtering and wave saturation. The upward propagation of GWs was suppressed when the zonal wind reversed from eastward to westward in the upper stratosphere. In regions where the zonal wind weakened but remained eastward, the weakened GWs could be due to their refraction to shorter vertical wavelengths.