[P-EM11] Coupling Processes in the Atmosphere-Ionosphere System

[PEM11-P05] Atomic Oxygen Ion–Neutral Collision Frequency Models at Ionospheric Temperatures

*Akimasa Ieda¹ (1.Institute for Space-Earth Environmental Research, Nagoya University)

Keywords:Burnside factor, ionospheric conductivity, collision frequency, charge-exchange collision, F region, oxygen

The collision between atomic oxygen and its first positive ion plays a major role in Earth's F region ionosphere. An accurate corresponding collision frequency model is necessary to quantitatively understand the ionosphere. However, the widely used classic Banks theoretical model typically provides a collision frequency that is 30% lower than the expectation from ionospheric observations. Accordingly, the classic collision frequency is often adjusted by multiplying it by a constant known as the Burnside factor. This correction-factor model adopted the classic model as its basis due to a misunderstanding that the classic model was based on a laboratory experiment; that is, the correction factor was originally meant to compensate for laboratory contamination.
In this study, a collision frequency model is constructed based on the laboratory experiment, and the resultant laboratory-based model is found to be consistent with ionospheric observations. In this construction, the impact of laboratory contamination is determined to be small (7%) and is mostly canceled by a misinterpretation regarding the conventional definitions of energy. Thus, the 30% difference is mainly caused by a theoretical error in the classic model itself. This error is energy-dependent and corrected by the later wide-energy theoretical model. Thus, the classic model cannot be corrected by a temperature-independent constant and should be replaced by the later model.

Ieda (JGR, 2021): https://doi.org/10.1029/2020JA028441