Variability of Venusian ionospheric electron density as observed by Pioneer Venus Orbiter and Venera 15/16 missions

Abstract

Electron density varies throughout the Venusian upper atmosphere and differs depending on factors related to time and location, providing an insight into the climate and atmosphere. The Pioneer Venus Orbiter and Venera 15/16 satellites conducted radio occultation experiments to measure electron density variations with atmospheric altitude. Using the archived electron density profiles from Pioneer Venus Orbiter and Venera 15/16, figures of electron density as a function of altitude were created and showed electron density peaks at approximately 140 km above Venus' surface. The electron density peak from the Pioneer Venus Orbiter and Venera 15/16 satellites matched those in publications from the Akatsuki and Venus Express satellites (Hensley et al., 20201; Tripathi et al., 20232). The electron density profiles also showed that the peak electron density varies between 5 x 103 cm-3 and 7 x 105 cm-3, depending on solar zenith angle, latitude, and longitude, demonstrating a strong spatiotemporal variability, which suggests that underlying ionization processes are dependent on these factors. Despite the differences in the peak electron density with latitude, longitude, and solar zenith angle, multiple satellite missions demonstrated that the Venusian ionospheric electron density peaks at approximately 140 km regardless of these factors. 

References: 1. Hensley, K., Withers, P., Girazian, Z., Pätzold, M., Tellmann, S., & Häusler, B. (2020). Dependence of dayside electron densities at Venus on solar irradiance. Journal of Geophysical Research: Space Physics, 125, e2019JA027167. https://doi.org/10.1029/2019JA027167