GRL—C. Y. Cullens, S. England, T. J. Immel, A. Maute, B. J. Harding, C. Triplett, J.J. Makela, et al.

Seasonal variations of monthly-zonal-mean small-scale perturbation amplitudes

Seasonal variations of monthly-zonal-mean small-scale perturbation amplitudes in (a) zonal-winds at 200 km, (b) temperature at 110 km, (c) zonal winds at 110 km, (d) temperature at 94 km averaged over (black) 0-15°N, (blue) 15-30°N, (red) 30-40°N from January 2020 to December 2021. Error bars represent one sigma.

Our understanding of the neutral wind variations in the lower and upper thermosphere is limited, among other, by the sparsity of observations. However, studies indicate that especially smaller scale wind perturbations might be linked to space weather effects such as the generation of plasma depletions. It motivated the present study to  analyze the seasonal variations of small-scale perturbations between 90 km to 250 km using temperature and winds measurements made by the Michelson Interferometer for Global High-Resolution Thermospheric Imaging (MIGHTI) instrument onboard the Ionospheric Connection Explorer (ICON) satellite in the latitude range of 0°-40° N in the year of 2020-2021.  Both small-scale perturbations (SSP) in temperature and winds below ~120 km show semi-annual variations, whereas annual variations of SSP for winds become dominant between 160 km to 250 km.  The largest wind SPP was observed at ~110-120 km throughout the year. Spatial variations of SSP at 90-250 km do not show clear latitudinal/longitudinal variations in both temperature and wind SSPs. The analysis suggests that seasonal variations of SSP between 90 and 250 km altitudes are influenced by both, sources distribution and background wind changes.

Cullens, C. Y., England, S. L., Immel, T. J., Maute, A., Harding, B. J., Triplett, C. C., et al. (2022). Seasonal variations of medium-scale waves observed by ICON-MIGHTI. Geophysical Research Letters, 49, e2022GL099383.