Validation of SSUSI-derived auroral electron  densities: comparisons to EISCAT data

Abstract. The coupling of the atmosphere to the space environment has become recognized as an important driver of atmospheric chemistry and dynamics. In order to quantify the effects of particle precipitation on the atmosphere, reliable global energy inputs on spatial scales commensurate with particle precipitation variations are required. To that end, we have validated auroral electron densities derived from the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) data products for average electron energy and electron energy flux by comparing them to EISCAT (European Incoherent Scatter Scientific Association) electron density profiles. This comparison shows that SSUSI far-ultraviolet (FUV) observations can be used to provide ionization rate and electron density profiles throughout the auroral region. The SSUSI on board the Defense Meteorological Satellite Program (DMSP) Block 5D3 satellites provide nearly hourly, 3000 km wide high-resolution (10 km×10 km) UV snapshots of auroral emissions. These UV data have been converted to average energies and energy fluxes of precipitating electrons. Here we use those SSUSI-derived energies and fluxes as input to standard parametrizations in order to obtain ionization-rate and electron-density profiles in the E region (90–150 km). These profiles are then compared to EISCAT ground-based electron density measurements. We compare the data from two satellites, DMSP F17 and F18, to the Tromsø UHF radar profiles. We find that differentiating between the magnetic local time (MLT) “morning” (03:00–11:00 MLT) and “evening” (15:00–23:00 MLT) provides the best fit to the ground-based data. The data agree well in the MLT morning sector using a Maxwellian electron spectrum, while in the evening sector using a Gaussian spectrum and accounting for backscattered electrons achieved optimum agreement with EISCAT. Depending on the satellite and MLT period, the median of the differences varies between 0 % and 20 % above 105 km (F17) and ±15 % above 100 km (F18). Because of the large density gradient below those altitudes, the relative differences get larger, albeit without a substantially increasing absolute difference, with virtually no statistically significant differences at the 1σ level.

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Validation of SSUSI derived ionization rates and electron densities

10.5194/angeo-2021-15 ◽

2021 ◽

Author(s):

Stefan Bender ◽

Patrick J. Espy ◽

Larry J. Paxton

Keyword(s):

Electron Density ◽

Electron Energy ◽

Spatial Scales ◽

Ionization Rate ◽

Space Environment ◽

Absolute Difference ◽

Particle Precipitation ◽

Density Profiles ◽

Average Electron Energy ◽

Electron Density Profiles

Abstract. The coupling of the atmosphere to the space environment has become recognized as an important driver of atmospheric chemistry and dynamics. In order to quantify the effects of particle precipitation on the atmosphere, reliable global energy inputs on spatial scales commensurate with particle precipitation variations are required. To that end, we have validated the Special Sensor Ultraviolet Spectrographic Imagers (SSUSI) products for average electron energy and electron energy flux by comparing to EISCAT electron density profiles. This comparison shows that SSUSI FUV observations can be used to provide ionization rate profiles throughout the auroral region. The SSUSI on board the Defense Meteorological Satellite Program (DMSP) Block 5D3 satellites provide nearly hourly, high-resolution UV snapshots of auroral emissions. These UV data have been converted to average energies and energy fluxes of precipitating electrons. Here we use those SSUSI-derived energies and fluxes to drive standard parametrizations in order to obtain ionization-rate and electron-density profiles in the E-region (90–150 km). These profiles are then compared to EISCAT ground-based electron density measurements. We compare the data from two satellites, DMSP F17 and F18, to the Tromsø UHF radar profiles. We find that differentiating between the magnetic local time (MLT) morning (3–11 h) and evening (15–23 h) provides the best fit to the ground-based data. The data agree well in the MLT morning sector using a Maxwellian electron spectrum, while in the evening sector using a Gaussian spectrum and accounting for bounce-electrons achieved optimum agreement with EISCAT. Depending on the satellite and MLT period, the median of the differences varies between 0 and 20 % above 105 km (F17) and ±15 % above 100 km (F18). Because of the large density gradient below those altitudes, the relative differences get larger, albeit without a substantially increasing absolute difference, with virtually no statistically significant differences at the 1 σ level.

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A Sporadic Third Layer in the Ionosphere of Mars

Science ◽

10.1126/science.1117755 ◽

2005 ◽

Vol 310 (5749) ◽

pp. 837-839 ◽

Cited By ~ 141

Author(s):

M. Pätzold ◽

S. Tellmann ◽

B. Häusler ◽

D. Hinson ◽

R. Schaa ◽

...

Keyword(s):

Electron Density ◽

Charge Exchange ◽

Layer Structure ◽

Electron Densities ◽

Ionospheric Layer ◽

Density Profiles ◽

Mars Express ◽

Radio Science ◽

Martian Ionosphere ◽

Electron Density Profiles

The daytime martian ionosphere has been observed as a two-layer structure with electron densities that peak at altitudes between about 110 and 130 kilometers. The Mars Express Orbiter Radio Science Experiment on the European Mars Express spacecraft observed, in 10 out of 120 electron density profiles, a third ionospheric layer at altitude ranges of 65 to 110 kilometers, where electron densities, on average, peaked at 0.8 × 1010 per cubic meter. Such a layer has been predicted to be permanent and continuous. Its origin has been attributed to ablation of meteors and charge exchange of magnesium and iron. Our observations imply that this layer is present sporadically and locally.

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Electron density profiles in the quiet lower ionosphere based on the results of modeling and experimental data

Annales Geophysicae ◽

10.5194/angeo-30-1345-2012 ◽

2012 ◽

Vol 30 (9) ◽

pp. 1345-1360 ◽

Cited By ~ 20

Author(s):

V. Barabash ◽

A. Osepian ◽

P. Dalin ◽

S. Kirkwood

Keyword(s):

Solar Activity ◽

Electron Density ◽

Lower Ionosphere ◽

Ionization Rate ◽

Number Density ◽

Density Profiles ◽

Oxide Concentration ◽

D Region ◽

Nitric Oxide Concentration ◽

Electron Density Profiles

Abstract. The theoretical PGI (Polar Geophysical Institute) model for the quiet lower ionosphere has been applied for computing the ionization rate and electron density profiles in the summer and winter D-region at solar zenith angles less than 80° and larger than 99° under steady state conditions. In order to minimize possible errors in estimation of ionization rates provided by solar electromagnetic radiation and to obtain the most exact values of electron density, each wavelength range of the solar spectrum has been divided into several intervals and the relations between the solar radiation intensity at these wavelengths and the solar activity index F10.7 have been incorporated into the model. Influence of minor neutral species (NO, H2O, O, O3) concentrations on the electron number density at different altitudes of the sunlit quiet D-region has been examined. The results demonstrate that at altitudes above 70 km, the modeled electron density is most sensitive to variations of nitric oxide concentration. Changes of water vapor concentration in the whole altitude range of the mesosphere influence the electron density only in the narrow height interval 73–85 km. The effect of the change of atomic oxygen and ozone concentration is the least significant and takes place only below 70 km. Model responses to changes of the solar zenith angle, solar activity (low–high) and season (summer–winter) have been considered. Modeled electron density profiles have been evaluated by comparison with experimental profiles available from the rocket measurements for the same conditions. It is demonstrated that the theoretical model for the quiet lower ionosphere is quite effective in describing variations in ionization rate, electron number density and effective recombination coefficient as functions of solar zenith angle, solar activity and season. The model may be used for solving inverse tasks, in particular, for estimations of nitric oxide concentration in the mesosphere.

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Error analysis of Abel retrieved electron density profiles from radio occultation measurements

Annales Geophysicae ◽

10.5194/angeo-28-217-2010 ◽

2010 ◽

Vol 28 (1) ◽

pp. 217-222 ◽

Cited By ~ 142

Author(s):

X. Yue ◽

W. S. Schreiner ◽

J. Lei ◽

S. V. Sokolovskiy ◽

C. Rocken ◽

...

Keyword(s):

Electron Density ◽

Radio Occultation ◽

Electron Content ◽

Electron Densities ◽

Density Profiles ◽

Total Electron ◽

The North ◽

Spring Equinox ◽

Electron Density Profiles ◽

Artificial Plasma

Abstract. This letter reports for the first time the simulated error distribution of radio occultation (RO) electron density profiles (EDPs) from the Abel inversion in a systematic way. Occultation events observed by the COSMIC satellites are simulated during the spring equinox of 2008 by calculating the integrated total electron content (TEC) along the COSMIC occultation paths with the "true" electron density from an empirical model. The retrieval errors are computed by comparing the retrieved EDPs with the "true" EDPs. The results show that the retrieved NmF2 and hmF2 are generally in good agreement with the true values, but the reliability of the retrieved electron density degrades in low latitude regions and at low altitudes. Specifically, the Abel retrieval method overestimates electron density to the north and south of the crests of the equatorial ionization anomaly (EIA), and introduces artificial plasma caves underneath the EIA crests. At lower altitudes (E- and F1-regions), it results in three pseudo peaks in daytime electron densities along the magnetic latitude and a pseudo trough in nighttime equatorial electron densities.

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