Auroral Ionosphere Model with PC Index as an Input

Vera Nikolaeva,Denis Rogov,Alexander Nikolaev,Oleg Troshichev,Evgeny Gordeev

doi:10.3390/atmos13030402

Abstract

Auroral Ionosphere Model (AIM-E) is designed to calculate chemical content in the high-latitude E region ionosphere and takes into account both the solar EUV radiation and the electron precipitation of magnetospheric origin. The latter is extremely important for auroral ionosphere chemistry especially in disturbed conditions. In order to maximize the AIM-E timing accuracy when simulating highly variable periods in the course of geomagnetic storms and substorms, we suggest to parameterize the OVATION-Prime empirical precipitation model with the ground-based Polar Cap (PC) index. This gives an advantage to: (1) perform ionospheric simulation with actual input, since PC index reflects the geoeffective solar wind conditions; (2) promptly assess the current geomagnetic situation, since PC index is available in real-time with 1 min resolution. The simulation results of AIM-E with OVATION-Prime (PC) demonstrate a good agreement with the ground-based incoherent scatter radar data (EISCAT UHF, Tromso) and with the vertical sounding data in the Arctic zone during events of intense particle precipitation. The model reproduces well the electron content calculated in vertical column (90–140 km) and critical frequency of sporadic E layer (fOEs) formed by precipitating electrons. The AIM-E (PC) model can be applied to monitor the sporadic E layer in real-time and in the entire high-latitude ionosphere, including the auroral and subauroral zones, which is important for predicting the conditions of radio wave propagation.

Highlights

Great efforts have been made recently in the field of space weather—the set of space factors that influence technical, industrial, and economic human activities
The use of minute values of the Polar Cap (PC) index as an input parameter of the high-latitude E region ionosphere model makes it possible to take into account the fast variations of electron precipitation flux during the periods with high geomagnetic activity
The energy spectra of precipitating electrons were reconstructed from the OVATIONPrime (PC) number flux and average energy outputs for: (1) diffuse electrons, assuming the Maxwellian distribution of the spectrum and (2) monoenergetic electron beams, using the normal distribution with a dispersion of a given value equal to half the difference between the channels adjacent to the channel of maximum energy

Summary

Introduction

Great efforts have been made recently in the field of space weather—the set of space factors that influence technical, industrial, and economic human activities. Space weather research, forecasting, and real-time diagnostics become the most urgent problems of modern near-space physics [1–5]. Space weather includes the complex chain of interactions between solar emissions (solar irradiation and solar plasma) and Earth’s magnetic field, while the ionosphere plays an important role in its diagnostics as a primary indicator of solarterrestrial interaction [6]. There are two main sources of atmospheric gas ionization by the extreme ultraviolet (EUV) solar radiation and the electron precipitation from the magnetosphere. Magnetospheric 1–10 keV electrons release their energy in the ionosphere E layer at 90–140 km altitudes, playing an important role in chemical, optical, and electrodynamic processes [7]. Due to precipitation of magnetospheric electrons, the Hall and Pedersen conductivities reach their maximum at these altitudes leading to development of horizontal ionospheric electrojets which close magnetospheric field-aligned currents [8,9]

Objectives

Methods

Results

Conclusion