Vertical incidence absorption calculated using electron density profiles from rocket experiments and comparison with observations during the winter anomaly

Smith, L. G.; Walton, E.K.; Mechtly, E. A.

doi:10.1016/0021-9169(78)90068-5

Cited by 22 publications

(7 citation statements)

References 19 publications

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“…It must be noted, however, that temperature changes should be related to dynamical perturbations with possible subsequent effects on NO densities. Also, collision frequency changes will result from pressure and temperature changes which will influence absorption without actually changing the electron density (see, for example, Smith et al [1978]).…”

Section: Discussionmentioning

confidence: 99%

Photochemical coupling between the thermosphere and the lower atmosphere: 2. D region ion chemistry and the winter anomaly

Solomon¹,

Reid²,

Roble³

et al. 1982

J. Geophys. Res.

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The primary source of ionization in the D region is provided by photoionization of nitric oxide by Lyman alpha radiation. The observation of enhanced electron densities in winter at middle and high latitudes therefore has often been attributed to enhanced nitric oxide densities in this region. This phenomenon is often called winter anomaly or winter anomalous absorption. The problem has been studied by combining an ion chemical model with a two‐dimensional time‐dependent model of the neutral atmosphere. The model extends from the ground to the base of the lower thermosphere and includes nitric oxide transport from the thermosphere as well as auroral production. The calculated nitric oxide distribution exhibits substantial seasonal and latitudinal variations, which strongly influence the ion chemical composition and simulate the winter anomaly very well. Other aspects of coupling between neutral and ion chemistry are also explored.

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Section: Discussionmentioning

confidence: 99%

Photochemical coupling between the thermosphere and the lower atmosphere: 2. D region ion chemistry and the winter anomaly

Solomon¹,

Reid²,

Roble³

et al. 1982

J. Geophys. Res.

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“…Note that the value of the proportionality factor between the collision frequency and the pressure has varied considerably in the literature, see, for example, Bennett et al [1972], Smith et al [1978], and Vuthaluru et al [2002]. The proportionality factor is generally obtained from laboratory measurements such as Phelps and Pack [1959].…”

Section: Friedrich-torkar Electron-neutral Collision Frequencymentioning

confidence: 99%

Calculating the absorption of HF radio waves in the ionosphere

et al. 2017

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It has long been known that the ionospheric absorption of HF radio waves is dependent on the electron density in the ionosphere. This paper examines two aspects of the absorption calculation that have not been as thoroughly investigated. First, the correct method to calculate ionospheric absorption is explored; while the Sen Wyller ray trace formulation is generally cited as the best approximation in the D and E regions of the ionosphere, the Appleton‐Hartree formulation is more consistent with the theory in the F region of the ionosphere. It is shown that either ray trace formulation can be used to calculate ionospheric absorption if the correct collision frequencies are utilized. Another frequently overlooked aspect of the attenuation calculation are the variations in the electron‐neutral and electron‐ion collision frequencies as a function of local time, season, latitude, and solar cycle. These variations result in differences on the order of 30% in the total ionospheric attenuation and should be included in absorption calculations.

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“…At mid-latitudes during daytime undisturbed solar flux conditions, 2.66-MHz radio waves are totally reflected from about 105 km altitude. In addition the major part of the absorption occurs in a 2-to 3-km layer immediately below the reflection level [Smith et al, 1978]. The absorption of the 2.66-MHz signal scattered from altitudes below about 85 km is usually small, 3 dB or less during the spring and summer months [Smith et al, 1978].…”

Section: Ar Xrmentioning

confidence: 99%

“…In addition the major part of the absorption occurs in a 2-to 3-km layer immediately below the reflection level [Smith et al, 1978]. The absorption of the 2.66-MHz signal scattered from altitudes below about 85 km is usually small, 3 dB or less during the spring and summer months [Smith et al, 1978]. Only during active solar periods, when the electron concentration at low altitudes is substantially increased, is the absorption large at these low altitudes.…”

Section: Ar Xrmentioning

confidence: 99%

Radar comparison of 2.66‐MHz and 40.92‐MHz signals scattered from the mesosphere

Røyrvik

1985

Radio Science

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Comparisons have been made between 2.66-MHz and 40.92-MHz radar signals simultaneously scattered from the mesosphere. Echoes were generally received from the same height ranges, indicating that the same scattering mechanism operates at both radar frequencies. A comparison of the observed radar cross sections was made for data obtained during the spring of 1984. Indications are that these echoes are due to scattering from turbulent irregularities in the refractive index. It has been possible to estimate the inner scale of turbulence from these data. The inner scale was found to be close to that estimated from turbulence theory. A comparison of the reflection coefficients indicates that a specular reflection process cannot account for the relative signal strength observed in these data. 1423

show abstract

Vertical incidence absorption calculated using electron density profiles from rocket experiments and comparison with observations during the winter anomaly

Cited by 22 publications

References 19 publications

Photochemical coupling between the thermosphere and the lower atmosphere: 2. D region ion chemistry and the winter anomaly

Photochemical coupling between the thermosphere and the lower atmosphere: 2. D region ion chemistry and the winter anomaly

Calculating the absorption of HF radio waves in the ionosphere

Radar comparison of 2.66‐MHz and 40.92‐MHz signals scattered from the mesosphere

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