AIM-E auroral ionosphere model adjustment for the regular E layer

The E-Region Auroral Ionosphere Model (AIM-E) was developed to determine the chemical composition and electron density in the auroral zone at E-layer heights (90–150 km). Solar and magnetic activity input parameters for AIM-E are the three-hour Ap index and the daily solar radio flux at a wavelength of 10.7 cm (index F10.7). In this paper, we compare AIM-E calculations of the electron density for the daytime with EUV radiation spectrum specified in two different ways: 1) the EUV spectrum theoretically calculated using the F10.7 index as an input parameter; 2) using TIMED satellite direct measurements of the EUV spectrum. We have corrected the EUVAC EUV radiation model to specify a photoionization source in AIM-E. Calculations of regular E-region critical frequencies show good agreement with the vertical sounding data from Russian high-latitude stations. Results we obtained make it possible to do a quick on-line assessment of the regular E layer, using the daily index F10.7 as an input parameter.

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Observations of the E-region horizontal winds in the auroral zone and at mid-latitudes by a ground-based interferometer

Annales Geophysicae ◽

10.1007/s00585-995-1172-y ◽

1995 ◽

Vol 13 (11) ◽

pp. 1172-1186 ◽

Cited By ~ 3

Author(s):

V. Fauliot ◽

G. Thuillier ◽

M. Hersé

Keyword(s):

Emission Line ◽

Michelson Interferometer ◽

Line Emission ◽

Theoretical Models ◽

Magnetic Activity ◽

Auroral Zone ◽

Empirical Models ◽

Neutral Wind ◽

Radar Observations ◽

E Region

Abstract. The MICADO instrument, consisting of a Michelson interferometer, has observed winds and temperatures during three winter campaigns in the auroral zone, and during 2 years at the Observatoire de Haute-Provence. The instrument observed the O(1S) oxygen emission line. Emission from this line originates from both the E- and F-regions. A method to separate the contribution from these two regions is presented for cases when the thermospheric component is comparable to that for the mesosphere. For the auroral latitudes, a mean model of the meridional and zonal neutral wind components as a function of magnetic activity and time is presented and compared to predictions from recent empirical models. For the mid-latitudes, several properties of the semi-diurnal tides are shown and compared to radar observations and predictions from recent theoretical models.

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Traits of sub-kilometre F-region irregularities as seen with the Swarm satellites

Annales Geophysicae ◽

10.5194/angeo-38-243-2020 ◽

2020 ◽

Vol 38 (1) ◽

pp. 243-261 ◽

Cited By ~ 4

Author(s):

Sharon Aol ◽

Stephan Buchert ◽

Edward Jurua

Keyword(s):

Electron Density ◽

European Space Agency ◽

Magnetic Activity ◽

Ionospheric Irregularities ◽

Magnetic Equator ◽

Longitudinal Distribution ◽

Density Data ◽

Solar Radio Flux ◽

F Region ◽

Swarm Satellites

Abstract. During the night, in the F-region, equatorial ionospheric irregularities manifest as plasma depletions observed by satellites, and they may cause radio signals to fluctuate. In this study, the distribution characteristics of ionospheric F-region irregularities in the low latitudes were investigated using 16 Hz electron density observations made by a faceplate which is a component of the electric field instrument (EFI) onboard Swarm satellites of the European Space Agency (ESA). The study covers the period from October 2014 to October 2018 when the 16 Hz electron density data were available. For comparison, both the absolute (dNe) and relative (dNe∕Ne) density perturbations were used to quantify the level of ionospheric irregularities. The two methods generally reproduced the local-time (LT), seasonal and longitudinal distribution of equatorial ionospheric irregularities as shown in earlier studies, demonstrating the ability of Swarm 16 Hz electron density data. A difference between the two methods was observed based on the latitudinal distribution of ionospheric irregularities where (dNe) showed a symmetrical distribution about the magnetic equator, while dNe∕Ne showed a magnetic-equator-centred Gaussian distribution. High values of dNe and dNe∕Ne were observed in spatial bins with steep gradients of electron density from a longitudinal and seasonal perspective. The response of ionospheric irregularities to geomagnetic and solar activities was also investigated using Kp index and solar radio flux index (F10.7), respectively. The reliance of dNe∕Ne on solar and magnetic activity showed little distinction in the correlation between equatorial and off-equatorial latitudes, whereas dNe showed significant differences. With regard to seasonal and longitudinal distribution, high dNe and dNe∕Ne values were often found during quiet magnetic periods compared to magnetically disturbed periods. The dNe increased approximately linearly from low to moderate solar activity. Using the high-resolution faceplate data, we were able to identify ionospheric irregularities on the scale of only a few hundred of metres.

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AIM-E: E-Region Auroral Ionosphere Model

Atmosphere ◽

10.3390/atmos12060748 ◽

2021 ◽

Vol 12 (6) ◽

pp. 748

Author(s):

Vera Nikolaeva ◽

Evgeny Gordeev ◽

Tima Sergienko ◽

Ludmila Makarova ◽

Andrey Kotikov

Keyword(s):

High Performance ◽

Reaction Rates ◽

Auroral Oval ◽

Auroral Zone ◽

Complex Nature ◽

Radio Waves ◽

Ionosphere Model ◽

High Latitude Region ◽

Wide Range ◽

E Region

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.

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New global electron density observations from GPS-RO in the D- and E-Region ionosphere

Journal of Atmospheric and Solar-Terrestrial Physics ◽

10.1016/j.jastp.2017.07.013 ◽

2018 ◽

Vol 171 ◽

pp. 36-59 ◽

Cited By ~ 2

Author(s):

Dong L. Wu

Keyword(s):

Electron Density ◽

E Region

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Empirical model of the E-region electron temperature around noon and at low magnetic activity

Planetary and Space Science ◽

10.1016/0032-0633(85)90104-7 ◽

1985 ◽

Vol 33 (8) ◽

pp. 909-914 ◽

Cited By ~ 5

Author(s):

S. Duhau ◽

M.C. Azpiazu

Keyword(s):

Electron Temperature ◽

Empirical Model ◽

Magnetic Activity ◽

E Region

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Survey of electron density changes in the daytime ionosphere over the Arecibo observatory due to lightning and solar flares

Scientific Reports ◽

10.1038/s41598-021-89662-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Caitano L. da Silva ◽

Sophia D. Salazar ◽

Christiano G. M. Brum ◽

Pedrina Terra

Keyword(s):

Electron Density ◽

Solar Flares ◽

Low Frequency ◽

Lower Ionosphere ◽

Weather Conditions ◽

Optical Observations ◽

Radio Waves ◽

D Region ◽

E Region ◽

Arecibo Observatory

AbstractOptical observations of transient luminous events and remote-sensing of the lower ionosphere with low-frequency radio waves have demonstrated that thunderstorms and lightning can have substantial impacts in the nighttime ionospheric D region. However, it remains a challenge to quantify such effects in the daytime lower ionosphere. The wealth of electron density data acquired over the years by the Arecibo Observatory incoherent scatter radar (ISR) with high vertical spatial resolution (300-m in the present study), combined with its tropical location in a region of high lightning activity, indicate a potentially transformative pathway to address this issue. Through a systematic survey, we show that daytime sudden electron density changes registered by Arecibo’s ISR during thunderstorm times are on average different than the ones happening during fair weather conditions (driven by other external factors). These changes typically correspond to electron density depletions in the D and E region. The survey also shows that these disturbances are different than the ones associated with solar flares, which tend to have longer duration and most often correspond to an increase in the local electron density content.

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