A fast, parameterized model of upper atmospheric ionization rates, chemistry, and conductivity

Abstract

Rapid specification of ionization rates and ion densities in the upper atmosphere is essential when many evaluations of the atmospheric state must be performed, as in global studies or analyses of on‐orbit satellite data. Though many models of the upper atmosphere perform the necessary specification, none provide the flexibility of computational efficiency, high accuracy, and complete specification. We introduce a parameterized, updated, and extended version of the GLobal AirglOW (GLOW) model, called GLOWfast, that significantly reduces computation time and provides comparable accuracy in upper atmospheric ionization, densities, and conductivity. We extend GLOW capabilities by (1) implementing the nitric oxide empirical model, (2) providing a new model component to calculate height‐dependent conductivity profiles from first principles for the 80–200 km region, and (3) reducing computation time. The computational improvement is achieved by replacing the full, two‐stream electron transport algorithm with two parameterizations: (1) photoionization (QRJ from Solomon and Qian ()) and (2) electron impact ionization (F0810 from Fang et al. (, )). We find that GLOWfast accurately reproduces ionization rates, ion and electron densities, and Pedersen and Hall conductivities independent of the background atmospheric state and input solar and auroral activity. Our results suggest that GLOWfast may be even more appropriate for low characteristic energy auroral conditions. We demonstrate in a suite of 3028 case studies that GLOWfast can be used to rapidly calculate the ionization of the upper atmosphere with few limitations on background and input conditions. We support these results through comparisons with electron density profiles from COSMIC.

High‐latitude ionospheric conductivity variability in three dimensions

“…We process the same in situ observations from the SSJ instrument on board the F6-F8 and F16-F18 DMSP satellites [Hardy et al, 1984;Kadinsky-Cade et al, 2004] used in M2015 with the GLobal AirglOW (GLOW) model [Solomon et al, 1988;Solomon and Abreu, 1989;Bailey et al, 2002] to produce altitude profiles of conductivities at the 1 s cadence of the DMSP electron flux observations without assumption of the electron energy spectra. GLOW yields altitude profiles of ionization and dissociation rates and ion and electron densities, which are used to compute profiles of the Hall and Pedersen conductivities, as described in detail in McGranaghan et al [2015b]. We use the median values over contiguous 60 s intervals, rather than the 60 s running average used in the M2015 height-integrated analysis, because the magnitudes of the height-dependent conductivities are much smaller than the height-integrated values and are more sensitive to outliers.…”

Self‐Consistent Modeling of Electron Precipitation and Responses in the Ionosphere: Application to Low‐Altitude Energization During Substorms

“…The neutral composition and temperature are obtained from NRLMSISE00 (Picone et al, 2002). The model determines altitude profiles of emission rates, ionization rates, electron density, and conductivity (McGranaghan, Knipp, Solomon, & Fang, 2015). Recently, the GLOW model (Solomon, 2017) has been improved to link with global general circulation models, hence making it possible to couple GLOW with the global ring current model, as reported in this paper.…”

Modes of high‐latitude auroral conductance variability derived from DMSP energetic electron precipitation observations: Empirical orthogonal function analysis

“…Further details about the GLOW code can be found in Solomon et al [1988] and McGranaghan et al [2015].…”