Analysis of NASA's DSN Venus Express radio occultation data for year 2014

TL;DR

This study analyzes 2014 Venus Express radio occultation data to derive atmospheric profiles, revealing how Venus' ionosphere and neutral atmosphere are differently affected by day/night cycles and latitude, with implications for understanding Venus' atmospheric dynamics.

Contribution

It provides an independent analysis of Venus' atmospheric profiles from VEX data, highlighting the influence of thermal inertia and zonal winds on atmospheric variations.

Findings

Venus' ionosphere is more affected by day/night conditions than latitude.

Neutral atmosphere shows stronger latitude dependence than day/night.

Profiles agree with previous studies, validating the analysis methods.

Abstract

The Venus Express Radio Science Experiment (VeRa) was part of the scientific payload of the Venus Express (VEX) spacecraft and was targeted at the investigation of Venus' atmosphere, surface, and gravity field as well as the interplanetary medium. This paper describes the methods and the required calibrations applied to VEX-VeRa raw radio occultation data used to retrieve vertical profiles of Venus' ionosphere and neutral atmosphere. In this work we perform an independent analysis of a set of 25 VEX, single-frequency (X-band), occultations carried out in 2014, recorded in open-loop at the NASA Deep Space Network. Our temperature, pressure and electron density vertical profiles are in agreement with previous studies available in the literature. Furthermore, our analysis shows that Venus' ionosphere is more influenced by the day/night condition than the latitude variations, while the neutral atmosphere experiences the opposite. Our scientific interpretation of these results is based on two major responsible effects: Venus' high thermal inertia and the zonal winds. Their presence within Venus' neutral atmosphere determine why in these regions a latitude dependence is predominant on the day/night condition. On the contrary, at higher altitudes the two aforementioned effects are less important or null, and Venus' ionosphere shows higher electron density peaks in the probed day-time occultations, regardless of the latitude.