A coupled thermosphere/ionosphere general circulation model

TLDR

The study presents steady‑state results of the first Eulerian thermosphere–ionosphere model under solar‑minimum equinox conditions. The NCAR TGCM was extended with a self‑consistent aeronomic scheme that couples neutral and ionospheric dynamics, computing global distributions of temperature, winds, neutral species, and ion species at each time step. The model’s global structure agrees reasonably with empirical models, demonstrating that first‑principles aeronomy can reproduce large‑scale thermosphere–ionosphere behavior using only external sources.

Abstract

The NCAR thermospheric general circulation model (TGCM) is extended to include a self‐consistent aeronomic scheme of the thermosphere and ionosphere. The model now calculates total temperature, instead of perturbation temperature about some specified global mean, global distributions of N(²D), N( 4 S) and NO , and a global ionosphere with distributions of O + , NO + , O 2 + , N 2 + , N + , electron density, and ion temperature as well as the usual fields of winds, temperature and major composition. Mutual couplings between the thermospheric neutral gas and ionospheric plasma occur at each model time step and at each point of the geographic grid. Steady state results for this first Eulerian model of the ionosphere, are presented for solar minimum equinox conditions. The calculated thermosphere and ionosphere global structure agrees reasonably well with the structure of these regions obtained from empirical models. This suggests that the major physical and chemical processes that describe the large‐scale structure of the thermosphere and ionosphere have been identified and a self‐consistent aeronomic scheme, based on first principles, can be used to calculate thermospheric and ionospheric structure considering only external sources.