  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.
