The Venus Global Ionosphere-Thermosphere Model (V-GITM): A Coupled
Thermosphere and Ionosphere Formulation
Abstract
This paper introduces the new Venus Global Ionosphere Thermosphere Model
(V-GITM) which incorporates the terrestrial GITM framework with
Venus-specific parameters, ion-neutral chemistry, and radiative
processes in order to simulate some of the observable features regarding
the temperatures, composition, and dynamical structure of the Venus
atmosphere from 70 km to 170 km. Atmospheric processes are included
based upon formulations used in previous Venus GCMs, several
augmentations exist, such as improved horizontal and vertical momentum
equations and tracking exothermic chemistry. Explicitly solving the
momentum equations allows for the exploration of its dynamical effects
on the day-night structure. In addition, V-GITM’s use of exothermic
chemistry instead of a strong heating efficiency accounts for the
heating due to the solar EUV while producing comparable temperatures to
empirical models. V-GITM neutral temperatures and neutral-ion densities
are compared to upper atmosphere measurements obtained from Pioneer
Venus and Venus Express. V-GITM demonstrates asymmetric horizontal wind
velocities through the cloud tops to the middle thermosphere and
explains the mechanisms for sustaining the wind structure. In addition,
V-GITM produces reasonable dayside ion densities and shows that the
neutral winds can carry the ions to the nightside via an experiment
advecting O$_2^+$.