Night-time electron temperature troughs in the equatorial topside ionosphere revealed from RPA experiments on the ISS-b satellite

1981 ◽  
Vol 43 (11) ◽  
pp. 1165-1173 ◽  
Author(s):  
E Sagawa ◽  
S Miyazaki ◽  
H Mori
Keyword(s):  
Electron Temperature ◽  
Topside Ionosphere ◽  
Night Time

Geographical and solar activity variations in the electron temperature of the upper F -region

1965 ◽  
Vol 286 (1407) ◽  
pp. 537-558 ◽  
Keyword(s):  
Electron Temperature ◽  
Electron Density ◽  
Geomagnetic Latitude ◽  
Minor Effect ◽  
Night Time ◽  
Temperature Variations ◽  
Geographical Variations ◽  
Magnetic Shell ◽  
Time Changes ◽  
A Minor

Electron temperature observations obtained in April-July 1962 on the Ariel I satellite have been further analysed by a statistical method. The general increase of electron temperature with latitude (amounting to about 500 degK) and with altitude between 400 and 1200 km, ( ca . 600 degK) previously reported, are confirmed. In addition, the dawn maximum of electron temperature found by other workers, which at the period of these observations is only a minor effect at 40° geomagnetic latitude, is found to become more pronounced near the magnetic equator. The geographical variations of electron temperature are shown to divide into distinct patterns characteristic of noon, dawn and midnight. The dawn pattern consists essentially of a longitude variation in the amplitude of the dawn maximum. All three patterns are closely associated with the geographical variations of electron density, and by examining the detailed correlation of temperature and density it is shown that the temperature variations result from changes in the collisional cooling rate of the electrons. This provides confirmation of the explanation of the dawn maximum suggested by Dalgarno, McElroy & Moffat (1963). Temperature variations due to changes in the far u.v. emission of the sun are considered. By day it is found that the electron temperature increases with 2800 Mc/s solar emission at a rate of (4.6 ± 2.3) degK per flux unit of 10 -22 Wcm -2 s -1 (c/s) -1 , while at night it decreases at a rate of 2.3 ± 2.7 degK/flux unit. Temperature variations in magnetic storms are compared with density enhancements described by Willmore & Henderson (1965). Electron density increases in the storm are always accompanied by a temperature reduction of about 180 degK, the storm-time changes showing a distinct magnetic shell structure. An instance of a temperature increase near the Brazilian geomagnetic anomaly is also given. Finally it is shown that these results lend support to the suggestion of a departure from thermal equilibrium in the night-time ionosphere.

Anisotropy of electron temperature in the topside ionosphere

1988 ◽  
Vol 8 (8) ◽  
pp. 151-154 ◽  
Author(s):  
K.-I. Oyama ◽  
T. Abe ◽  
S. Watanabe
Keyword(s):  
Electron Temperature ◽  
Topside Ionosphere

scholarly journals Electron Densities and Scale Heights in the Mid-latitude Topside Ionosphere

1967 ◽  
Vol 20 (4) ◽  
pp. 401 ◽  
Author(s):  
PL Dyson
Keyword(s):  
Electron Density ◽  
Northern Hemisphere ◽  
Scale Height ◽  
Topside Ionosphere ◽  
Electron Densities ◽  
Night Time ◽  
Transition Level ◽  
Latitude Region ◽  
Latitudinal Variations

The diurnal and latitudinal variations of electron density and plasma scale height in the topside ionosphere during summer and winter have been calculated from Alouette I ionograms recorded at Woomera. The electron density behaviour is anomalous in that the winter night-time values are generally as large or larger than those occurring during the day. At heights near 1000 km the winter night-time values are greater than those for night-time summer. The behaviour of the scale height is very similar to that reported by others for the mid-latitude region of the northern hemisphere and implies that at night-time the transition level from 0+ to lighter ions occurs at heights of about 550 km in summer and 500 km in winter.

scholarly journals Modelling the influence of meteoric smoke particles on artificial heating in the D-region

2021 ◽  
Vol 39 (6) ◽  
pp. 1055-1068
Author(s):  
Margaretha Myrvang ◽  
Carsten Baumann ◽  
Ingrid Mann
Keyword(s):  
Electron Temperature ◽  
Radio Wave ◽  
Electron Density ◽  
Electron Attachment ◽  
Radio Waves ◽  
Night Time ◽  
Smoke Particles ◽  
D Region ◽  
Meteoric Smoke ◽  
Artificial Heating

Abstract. We investigate if the presence of meteoric smoke particles (MSPs) influences the electron temperature during artificial heating in the D-region. By transferring the energy of powerful high-frequency radio waves into thermal energy of electrons, artificial heating increases the electron temperature. Artificial heating depends on the height variation of electron density. The presence of MSPs can influence the electron density through charging of MSPs by electrons, which can reduce the number of free electrons and even result in height regions with strongly reduced electron density, so-called electron bite-outs. We simulate the influence of the artificial heating by calculating the intensity of the upward-propagating radio wave. The electron temperature at each height is derived from the balance of radio wave absorption and cooling through elastic and inelastic collisions with neutral species. The influence of MSPs is investigated by including results from a one-dimensional height-dependent ionospheric model that includes electrons, positively and negatively charged ions, neutral MSPs, singly positively and singly negatively charged MSPs, and photochemistry such as photoionization and photodetachment. We apply typical ionospheric conditions and find that MSPs can influence both the magnitude and the height profile of the heated electron temperature above 80 km; however, this depends on ionospheric conditions. During night, the presence of MSPs leads to more efficient heating and thus a higher electron temperature above altitudes of 80 km. We found differences of up to 1000 K in electron temperature for calculations with and without MSPs. When MSPs are present, the heated electron temperature decreases more slowly. The presence of MSPs does not much affect the heating below 80 km for night conditions. For day conditions, the difference between the heated electron temperature with MSPs and without MSPs is less than 25 K. We also investigate model runs using MSP number density profiles for autumn, summer and winter. The night-time electron temperature is expected to be 280 K hotter in autumn than during winter conditions, while the sunlit D-region is 8 K cooler for autumn MSP conditions than for the summer case, depending on altitude. Finally, an investigation of the electron attachment efficiency to MSPs shows a significant impact on the amount of chargeable dust and consequently on the electron temperature.

scholarly journals Yearly variations in the low-latitude topside ionosphere

2000 ◽  
Vol 18 (7) ◽  
pp. 789-798 ◽  
Author(s):  
G.J. Bailey ◽  
Y. Z. Su ◽  
K.-I. Oyama
Keyword(s):  
Electron Temperature ◽  
Electron Density ◽  
Plasma Temperature ◽  
Magnetic Activity ◽  
Topside Ionosphere ◽  
Low Latitude ◽  
Yearly Variation ◽  
The North ◽  
The Asymmetry ◽  
The Relationship

Abstract. Observations made by the Hinotori satellite have been analysed to determine the yearly variations of the electron density and electron temperature in the low-latitude topside ionosphere. The observations reveal the existence of an equinoctial asymmetry in the topside electron density at low latitudes, i.e. the density is higher at one equinox than at the other. The asymmetry is hemisphere-dependent with the higher electron density occurring at the March equinox in the Northern Hemisphere and at the September equinox in the Southern Hemisphere. The asymmetry becomes stronger with increasing latitude in both hemispheres. The behaviour of the asymmetry has no significant longitudinal and magnetic activity variations. A mechanism for the equinoctial asymmetry has been investigated using CTIP (coupled thermosphere ionosphere plasmasphere model). The model results reproduce the observed equinoctial asymmetry and suggest that the asymmetry is caused by the north-south imbalance of the thermosphere and ionosphere at the equinoxes due to the slow response of the thermosphere arising from the effects of the global thermospheric circulation. The observations also show that the relationship between the electron density and electron temperature is different for daytime and nighttime. During daytime the yearly variation of the electron temperature has negative correlation with the electron density, except at magnetic latitudes lower than 10°. At night, the correlation is positive.Key words: Ionosphere (equatorial ionosphere; ionosphere-atmosphere interactions; plasma temperature and density)

scholarly journals The correlation between electron temperature and density in the topside ionosphere during 2006-2009

2015 ◽  
Vol 120 (12) ◽  
pp. 10,724-10,739 ◽  
Author(s):  
Fanfan Su ◽  
Wenbin Wang ◽  
Alan G. Burns ◽  
Xinan Yue ◽  
Fuying Zhu
Keyword(s):  
Electron Temperature ◽  
Topside Ionosphere

scholarly journals Diurnal, seasonal and latitudinal variations of electron temperature measured by the SROSS C2 satellite at 500 km altitude and comparison with the IRI

2002 ◽  
Vol 20 (6) ◽  
pp. 807-815 ◽  
Author(s):  
P. K. Bhuyan ◽  
M. Chamua ◽  
P. Subrahmanyam ◽  
S. C. Garg
Keyword(s):  
Electron Temperature ◽  
Plasma Temperature ◽  
Latitudinal Gradients ◽  
Local Times ◽  
Activity Period ◽  
Average Height ◽  
Night Time ◽  
Latitude Belt ◽  
Average Value ◽  
Latitudinal Variations

Abstract. The diurnal, seasonal and latitudinal variations of electron temperature Te, measured by the SROSS C2 satellite at equatorial and the low-latitudes during the low solar activity period of 1995–1997 are investigated. The average height of the satellite was ~ 500 km and it covered the latitude belt of –31° to 34° and the longitude range of 40°–100°. Te varies between 700–800 K during night-time (20:00–04:00 LT), rises sharply during sunrise (04:00–06:00 LT) to reach a level of ~ 3500 K within a couple of hours and then falls between 07:00–10:00 LT to a daytime average value of ~ 1600 K. A secondary maximum is observed around 16:00–18:00 LT in summer. Latitudinal gradients in Te have been observed during the morning enhancement and daytime hours. Comparison of measured and International Reference Ionosphere (IRI) predicted electron temperature reveals that the IRI predicts nighttime Te well within ~ 100 K of observation, but at other local times, the predicted Te is less than that measured in all seasons.Key words. Ionosphere, equatorial ionosphere, plasma temperature, and density

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