Gravity Wave Characteristics and Their Global Impact on the Ionosphere-Thermosphere System: Insights from NASA AWE and GNSS TEC Observations

Gravity Wave Characteristics and Their Global Impact on the Ionosphere-Thermosphere System: Insights from NASA AWE and GNSS TEC Observations
Sreelekshmi Radhakrishnan Girijakumary, Xian Lu

Atmospheric gravity waves are the key drivers of transporting energy and momentum from lower atmosphere to the upper atmosphere, significantly influencing the Ionosphere- Thermosphere (IT system). These waves can interact with the upper atmosphere and contribute to large-scale ionospheric disturbances. Understanding their spatio-temporal characteristics is crucial for quantifying its impact in IT variability. Despite its significant role in coupling the lower and upper atmospheric layers, its global characteristics and its impact on the IT region is challenging to observe due to observational limitations and model constraints in resolving these small-scale waves. Our study utilizes the NASA’s Atmospheric Waves Experiment (AWE), launched in November 2023, aboard the International Space station which provides the first global characterization of small-scale atmospheric gravity waves (AGWs) in the mesopause region (~87-90 km). This data enables the detailed investigation on the global distribution and the variability of mesospheric gravity waves using high resolution radiance and temperature measurements. We calculate the TID-induced variances of electron density using GNSS which are used as a proxy for ionospheric variability. We then correlate the TID variances with GW variances observed by AWE as well as the geomagnetic indices (Dst and AE), to examine the relative contribution from lower-atmosphere (GWs around 87 km) and from magnetosphere to the meso-scale ionospheric variabilities (i.e., TID variances). Furthermore, we explore the possibility of using AWE to derive GW momentum and energy fluxes, which will lead to further insights on how to quantify their role in mean-wave interaction and wave-induced instability.