AIM-E: E-Region Auroral Ionosphere Model

Abstract

The auroral oval is the high-latitude region of the ionosphere characterized by strong variability of its chemical composition due to precipitation of energetic particles from the magnetosphere. The complex nature of magnetospheric processes cause a wide range of dynamic variations in the auroral zone, which are difficult to forecast. Knowledge of electron concentrations in this highly turbulent region is of particular importance because it determines the propagation conditions for the radio waves. In this work we introduce the numerical model of the auroral E-region, which evaluates density variations of the 10 ionospheric species and 39 reactions initiated by both the solar extreme UV radiation and the magnetospheric electron precipitation. The chemical reaction rates differ in more than ten orders of magnitude, resulting in the high stiffness of the ordinary differential equations system considered, which was solved using the high-performance Gear method. The AIM-E model allowed us to calculate the concentration of the neutrals NO, N(4S), and N(2D), ions N+, N2+, NO+, O2+, O+(4S), O+(2D), and O+(2P), and electrons Ne, in the whole auroral zone in the 90‒150 km altitude range in real time. The model results show good agreement with observational data during both the quiet and disturbed geomagnetic conditions.

Auroral Ionosphere Model with PC Index as an Input

“…The AIM-E model allows us to estimate the concentration of the small neutral components, ions, and electrons in the whole auroral ionosphere E region [16]. The model is capable of reproducing the ionospheric response to the geomagnetic storms and substorms with sufficient accuracy, and can be used to describe the dynamics of chemical content in the auroral oval during disturbed periods.…”

“…This method significantly reduces the computational costs and, at the same time, ensures a sufficient numerical solution accuracy. High performance of the AIM-E model allows to calculate, in real-time, the entire auroral zone composition covering the altitude range of 90-140 km in real-time, taking into account different levels of solar ultraviolet radiation [26] and for high variability of electron precipitation in auroral zone [16].…”

“…Many theoretical problems and practical applications related to the high-latitude ionosphere require complex analysis of regular ground and spacecraft measurements in combination with the numerical modeling of the geophysical processes. The Auroral Ionosphere Model (AIM-E) [16] is specially designed for the high-latitude E region of the ionosphere and takes into account the solar EUV radiation flux and the global spatial distribution of precipitating magnetospheric electrons. Both ionization sources can be set using actual spacecraft measurements or/and empirical models.…”

“…Both ionization sources can be set using actual spacecraft measurements or/and empirical models. In the case of electron precipitation input, the spacecraft-based measurements provide a high accuracy of ionospheric solution along the spacecraft trajectory, while the empirical model of precipitating particle distribution can be used for a climatological modeling to describe the large-scale ionosphere dynamics in the auroral zone [16]. AIM-E provides the chemical composition of the high-latitude ionosphere in the altitude range from 90 to 140 km.…”

The role of the inner radiation belt dynamic in the generation of auroral-type sporadic E-layers over south American magnetic anomaly

“…The Es layers associated with the vertical shear in the horizontal tidal wind are normally classified into the flat (Es f ), high (Es h ), cusp (Es c ), and low (Es l ) types, while the Es layers associated with the low-energy EP is observed in the ionograms as traces of range spreading echoes, named Es a layer (e.g., Moro et al, 2022;Kirkwood and Nilsson, 2000;Piggott and Rawer, 1978). They are commonly detected in the auroral regions produced by the auroral particle ionization (Nikolaeva et al, 2021) from the outer radiation belt (Blum et al, 2013) and peculiarly over the SAMA region due the low-energy EP from the inner radiation belt (Batista and Abdu 1977;Gonzalez et al, 1987;Moro et al, 2022).…”