Experimental investigations of the ionospheric E-layer

Robinson, B. J.

doi:10.1088/0034-4885/22/1/308

Cited by 31 publications

(7 citation statements)

References 102 publications

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“…There appear to be four rather definite cusps on the ionograms near 1225 P.M., the time the rocket is passing through the E region. It is well established that quite large retardations can be produced by rather insignificant inflections on the electron concentration curve [Robinson, 1959]. We conjecture that these cusps may be magnified manifestations of electron concentration inflections related to the thermal structure measured by the ion trap.…”

Section: Changes In Photo Current Produced By Precession Would Be Negmentioning

confidence: 71%

Evidence for temperature stratification in theEregion

Knudsen¹,

Sharp²

1965

J. Geophys. Res.

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The ion temperature of the upper atmosphere at local noon in the region from 100 to 160 km has been measured directly by means of an ion trap. The ion temperature is expected to be the same as that of the neutral particles, since analysis shows that the thermal relaxation time of ions to neutrals is shorter than that of ions to plasma in the above height range. Above 120 km the experimental temperature profile contains what appears to be a wave‐like temperature variation superimposed on an otherwise reasonable thermosphere profile. The peak‐to‐trough amplitude of the temperature variation is 200°K, and the average wavelength is approximately 12 km. The thermosphere temperature profile parallels predicted thermosphere profiles but may be systematically high. At and below 115 km the shape of the profile deviates from predicted profiles. The temperature is high and increases downward; this increase may be caused by aerodynamic heating of the ions before they enter the trap. The amplitude of the wave‐like temperature variation is consistent with that expected from a gravity wave producing a horizontal wind velocity of 150 m/sec. However, the vertical wavelength is smaller than that believed possible for gravity waves in the altitude interval of interest. On the other hand, measured total extreme ultraviolet energy is insufficient to maintain a quasi‐steady‐state temperature profile of the shape observed.

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Section: Changes In Photo Current Produced By Precession Would Be Negmentioning

confidence: 71%

Evidence for temperature stratification in theEregion

Knudsen¹,

Sharp²

1965

J. Geophys. Res.

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“…Only the F region is observable at night, the daytime E layer first appearing around the time of sunrise at sea level. Numerous transient minor stratifications characterize the E layer for the next hour or so [Baker, 1964;Robinson, 1959], but the structure eventually settles into a regular E layer.…”

Section: Resultsmentioning

confidence: 99%

Frequency and duration of disturbances in the mid‐latitude F region of the ionosphere

Lambert¹

1988

Radio Science

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Disturbances of the ionospheric F region at two well‐separated mid‐latitude stations were identified on rapid run ionograms by spread echoes, blackouts, and anomalies in structure or critical frequency. The diurnal variation in the probability of disturbance consistently shows minima around sunrise and sunset. Details such as a brief postsunset enhancement in winter are revealed by the fine time resolution of the data. Disturbance probabilities were lowest in autumn and spring (8% and 9%), while that for winter (33%) exceeded the summer level (20%). Spread F constituted 32% of the events, and disturbances producing sharply defined ionogram signatures 77%, with some overlapping of types. The majority of disturbances were not correlated with geomagnetic phenomena. Disturbances at the two stations were essentially independent (spatial correlation of 0.15). Spread F events were of longer duration (25 min) than sharp disturbances (20 min). TIDs were the exception, with a most probable duration of 80 min, but accounted for only 8.3% of the sharp disturbances. The absence of disturbances in the F region at dusk and especially at dawn coincides with periods of instability in the E region.

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“…In applying the photochemical theory to the normal E-layer controlled by the solar EUV radiation, it is generally satisfactory to assume ∂N/∂t = 0. For a simple equilibrium E-layer in an isothermal atmosphere, the critical frequency f o E (in units of Hz) of the E-layer can be expressed by the equation (m. k. s. units) [1,2] f o E = 9[(q 0 /α) cos χ] 0.25 ,…”

Section: Introductionmentioning

confidence: 99%

Features of the Polar Ionosphere at Zhongshan Station in Antarctic

Shen

Wang

et al. 2005

Chinese J. Geophys.

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We use the data of the ionospheric critical frequencies, foF2 and foE, observed by a Digisonde Portable Sounder (DPS-4) at the Zhongshan station of Antarctica in 1996, the hemispheric power index and the midnight equatorward boundary of the aurora estimated by the observations of American NOAA and DMSP satellites, to investigate features of the polar ionosphere. The results show that under a quiet environment of the solar activity and geomagnetic variation at the winter polar night, when the station lies at the center of the polar cleft at magnetic noon, the ionization density of the ionosphere attained to a maximum of the diurnal variation. During several hours both in the morning and afternoon, the ionized effect of the auroral energy particles is also important. At night the electron density is very low when the station situates at the polar cap area. During the summer polar daylight, the ionized effect of the solar EUV radiation makes the ionospheric electron density much larger and the peak time of the diurnal variation of foF2 1∼2h earlier than that in winter. During a strong geomagnetic disturbance, the locations of both the cleft and aurora move to lower latitudes, and the ionospheric electron density over the Zhongshan station decreases significantly. For a moderate disturbed situation, things become more complex: The strength of ionization caused by soft particles in the cleft around the magnetic noon decreases somewhat, while ionization caused by higher energy particles in the aurora area increases a lot both in the morning and afternoon.Key words Ionospheric foF2 and foE, Soft particle in the cleft, Particle ionization in the aurora, Solar EUV radiation

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Experimental investigations of the ionospheric E-layer

Cited by 31 publications

References 102 publications

Evidence for temperature stratification in theEregion

Evidence for temperature stratification in theEregion

Frequency and duration of disturbances in the mid‐latitude F region of the ionosphere

Features of the Polar Ionosphere at Zhongshan Station in Antarctic

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