Venusian ionosphere during deep solar minima: Some new insights using Akatsuki radio science experiment – data set

Radio science (RS) payload onboard the Akatsuki orbiter is conducting radio occultation experiments around Venus from 2015 onward. RS is probing the Venusian atmosphere/ionosphere using an X-band radio signal which is generated by an ultra-stable oscillator (USO) with stability around 10^--12 Hz/Hz. The stability of the generated signal has enabled us to observe fluctuations in the Venusian ionosphere in minute detail. Another uniqueness of this mission is its equatorial orbit, which helped to investigate the atmosphere/ionosphere near the equatorial region during local noon hours [1].

The transmitted signal from the spacecraft passes through the Venusian atmosphere and is received at the Usuda Deep Space Center (UDSC), Japan; Indian Deep Space Network (IDSN), India; and Ground Station Weilheim (WHM), Germany. We analyzed the received data using in-house developed software [2] to estimate the phase change in radio signals due to the target medium and retrieved the electron density profile using the geometrical optics method [3]. The obtained electron profiles are simulated by the 1- dimensional photochemical model (1D-PCM) [4]. These data sets, which are used to generate figures in the manuscript “Venusian ionosphere during deep solar minima: Some new insights using Akatsuki radio science experiment” by Tripathi et al. (JGR-Planet), are archived here. A description of the data set used in each plot is given in the readme file of the corresponding folder. Each folder also contains a Gnuplot script file to plot the figure.

Reference:

[1] Imamura, T., Ando, H., Tellmann, S., Pätzold, M., Häusler, B., Yamazaki, A., . . . others (2017). Initial performance of the radio occultation experiment in the Venus orbiter mission Akatsuki. Earth, Planets and Space, 69(1), 1 – 11.

[2] Tripathi, K.R., Choudhary, R.K. and Jayalal, L., 2022. On the estimation of frequency residuals in a radio occultation experiment. Monthly Notices of the Royal Astronomical Society, 517(1), pp.776-786.

[3] Fjeldbo, G., Kliore, A.J. and Eshleman, V.R., 1971. The neutral atmosphere of Venus as studied with the Mariner V radio occultation experiments. The Astronomical Journal, 76, p.123.

[4] Ambili, K.M., Babu, S.S. and Choudhary, R.K., 2019. On the relative roles of the neutral density and photochemistry on the solar zenith angle variations in the V2 layer characteristics of the Venus ionosphere under different solar activity conditions. Icarus, 321, pp.661-670.