A coupled thermosphere/ionosphere general circulation model

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(4S) and NO, and a global ionosphere with distributions of O+,NO+, O2+, N2+, 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.

The importance of geomagnetic field changes versus rising CO2levels for long-term change in the upper atmosphere

“…The model is well-established and has been widely used in the thermosphere-ionosphere community, so we will only mention a few important aspects here. More information on the original model setup can be found in Roble et al (1988) and Richmond et al (1992). An up-to-date overview of the development of the TIE-GCM and its current state, including some model validation examples, is provided by Qian et al (2014) and references therein.…”

The winter helium bulge revisited

“…The helium minor species equation has been implemented in the TIEGCM in the form of a mass mixing ratio equation. According to Roble et al [1988], the continuity equation of a minor species' mass mixing ratio in the TIEGCM is written as…”

“…But the mechanisms responsible for the helium distribution have not been adequately described nor has helium been implemented in modern general circulation models to enable a more complete evaluation. In this work, we implement a minor gas helium module into the National Center for Atmospheric ResearchThermosphere Ionosphere Electrodynamics general circulation model (NCAR-TIEGCM) [Roble et al, 1988;Richmond et al, 1992] to observe helium in the context of a first principles, self-consistent model and to test early theories for helium bulge formation. The TIEGCM allows, for the first time, the mechanisms responsible for the formation of the winter helium bulge to be studied in the context of a fully coupled thermosphere-ionosphere model environment with new analysis tools and a more complete description.…”

Meridional thermospheric neutral wind at high latitude over a full solar cycle

“…It would be interesting to compare it with results from the new ESR radar located at higher latitude and also from theoretical works, like the thermosphere ionosphere global circulation model (TIGCM) (Roble et al,1988), or the coupled thermosphere ionosphere model (CTIM) (Fuller-Rowell et al,1987).…”