The electron content of the ionosphere at middle latitudes in summer

1964 ◽  
Vol 279 (1379) ◽  
pp. 497-509 ◽  
Keyword(s):  
Electron Density ◽  
Faraday Rotation ◽  
Middle Latitude ◽  
Diurnal Variations ◽  
Slab Thickness ◽  
Electron Content ◽  
Middle Latitudes ◽  
Maximum Electron Density ◽  
Short Period ◽  
Made In

Measurements of the electron content of the ionosphere obtained from observations of the differential Faraday rotation of moon-reflected signals on two closely spaced frequencies are described. Accurate values of the electron content on many successive days near the summer solstices of 1960 and 1961 are presented, and compared and contrasted with similar measurements made in the winter of 1960 (Evans & Taylor 1961). The diurnal variations of electron content, short-period irregular fluctuations in electron content, equivalent slab thickness and top-to-bottom ratio are all found to differ from those observed in winter. The middle latitude seasonal anomaly is found to be less prominent in the electron content than in the maximum electron density .

scholarly journals Reconstruction of F2 layer peak electron density based on operational vertical total electron content maps

2013 ◽  
Vol 31 (7) ◽  
pp. 1241-1249 ◽  
Author(s):  
T. Gerzen ◽  
N. Jakowski ◽  
V. Wilken ◽  
M. M. Hoque
Keyword(s):  
Electron Density ◽  
Total Electron Content ◽  
Slab Thickness ◽  
Electron Content ◽  
Vertical Total Electron Content ◽  
Radio Communication ◽  
Total Electron ◽  
Current State ◽  
Maximum Electron Density ◽  
Layer Peak

Abstract. Electron density is the major determining parameter of the ionosphere. Especially the maximum electron density of the F2 layer in the ionosphere, NmF2, is of particular interest with regard to the HF radio communication applications as well as for characterizing the ionosphere. In this paper we present a new method to generate global maps of NmF2. The main principle behind this approach is to use the information about the current state of the ionosphere included in global total electron content (TEC) maps as well as the relationship between total electron content, equivalent slab thickness and F2 layer peak density. Modeling of slab thickness is an interim step in our reconstruction approach. Thus, results showing the diurnal and seasonal variations and effects of solar activity on the modeled slab thickness values are given. In addition a comparison of the reconstructed NmF2 maps with measurements from several ionosonde stations as well as with the global NmF2 model NPDM is presented. Since 2011 the described method has been used at DLR Neustrelitz to generate NmF2 maps as operational service. These maps are freely available via the Space Weather Application Center Ionosphere SWACI (http://swaciweb.dlr.de).

Strong equatorial plasma bubble associated with prominent TEC enhancement observed at mid-latitude ionosphere under the quiescent condition

2021 ◽  
Author(s):  
Fuqing Huang ◽  
Jiuhou Lei ◽  
Chao Xiong
Keyword(s):  
Electron Density ◽  
Electron Content ◽  
Radio Waves ◽  
Plasma Bubble ◽  
Total Electron ◽  
Middle Latitudes ◽  
Multiple Observations ◽  
Equatorial Plasma Bubbles ◽  
Low Latitudes

<p>Equatorial plasma bubbles (EPBs) are typically ionospheric irregularities that frequently occur at the low latitudes and equatorial regions, which can significantly affect the propagation of radio waves. In this study, we reported a unique strong EPB that happened at middle latitudes over the Asian sector during the quiescent period. The multiple observations including total electron content (TEC) from Beidou geostationary satellites and GPS, ionosondes, in-situ electron density from SWARM and meteor radar are used to explore the characteristic and mechanism of the observed EPB. The unique strong EPB was associated with great nighttime TEC/electron density enhancement at the middle latitudes, which moves toward eastward. The potential physical processes of the observed EPB are also discussed.</p>

The electron content of the ionosphere in winter

1961 ◽  
Vol 263 (1313) ◽  
pp. 189-211 ◽  
Keyword(s):  
Total Electron Content ◽  
Faraday Rotation ◽  
Scale Height ◽  
Electron Content ◽  
Radio Waves ◽  
Total Electron ◽  
Neutral Particles ◽  
Short Period ◽  
Wide Scatter ◽  
Magnetic Index

Observations at two closely spaced frequencies of the Faraday rotation of moon-reflected radio waves are described. These measurements have provided accurate values for the total electron content of the ionosphere for many hours on successive days. The observations reported here span a period of one month during the winter of 1960. Short-period fluctuations of the total electron content were observed. These were of about 2 to 3% in amplitude and occurred chiefly during the day-time. The gross shape of the F 2 region as determined by the ratio of the number of electrons above the F 2 peak to the number below was roughly constant during the day, but showed a wide scatter of values at night. The scale height of the ionizable constituent at the F 2 peak was found to be about the same as that of the neutral particles during the day, indicating almost complete mixing. At night, the scale height of the ionizable constituent appeared to increase with the planetary magnetic index K p . It is not possible to say if this was the result of heating of the region or the consequence of electrodynamic drifts.

scholarly journals Obtaining Ionospheric Conditions according to Data of Navigation Satellites

2015 ◽  
Vol 2015 ◽  
pp. 1-16 ◽  
Author(s):  
Olga Maltseva ◽  
Natalia Mozhaeva
Keyword(s):  
Critical Frequency ◽  
Bench Mark ◽  
Slab Thickness ◽  
Electron Content ◽  
Efficiency Coefficient ◽  
Low Latitude ◽  
Total Electron ◽  
Average Value ◽  
Middle Latitudes ◽  
Critical Frequency Fof2

Defining ionospheric conditions, the deviation of the observational value of the total electron content TEC(obs), measured by means of navigation satellites, from a median is a bench mark. According to more than 40 ionospheric stations during April 2014 it is shown that synchronism of change of deviations of TEC and critical frequency foF2 of the ionosphere is kept under quiet and moderate disturbed conditions. This fact allows to use a median of the equivalent slab thicknessτ(med) as a reliable calibration factor to calculate foF2 from TEC(obs). The efficiency coefficient of joint use ofτ(med) and TEC(obs) changes from 1.5 to 4 with average value 2.2 across the globe. The highest coefficient corresponds to middle latitudes, however the estimations obtained for high- and low-latitude areas indicate possibility to useτ(med) and TEC(obs) in these areas.

scholarly journals Neural network based tomographic approach to detect earthquake-related ionospheric anomalies

2011 ◽  
Vol 11 (8) ◽  
pp. 2341-2353 ◽  
Author(s):  
S. Hirooka ◽  
K. Hattori ◽  
M. Nishihashi ◽  
T. Takeda
Keyword(s):  
Neural Network ◽  
Electron Density ◽  
Electron Content ◽  
Total Electron ◽  
Ionospheric Tomography ◽  
Maximum Electron Density ◽  
Southern Side ◽  
Global Ionosphere Map ◽  
Residual Minimization ◽  
Tomographic Approach

Abstract. A tomographic approach is used to investigate the fine structure of electron density in the ionosphere. In the present paper, the Residual Minimization Training Neural Network (RMTNN) method is selected as the ionospheric tomography with which to investigate the detailed structure that may be associated with earthquakes. The 2007 Southern Sumatra earthquake (M = 8.5) was selected because significant decreases in the Total Electron Content (TEC) have been confirmed by GPS and global ionosphere map (GIM) analyses. The results of the RMTNN approach are consistent with those of TEC approaches. With respect to the analyzed earthquake, we observed significant decreases at heights of 250–400 km, especially at 330 km. However, the height that yields the maximum electron density does not change. In the obtained structures, the regions of decrease are located on the southwest and southeast sides of the Integrated Electron Content (IEC) (altitudes in the range of 400–550 km) and on the southern side of the IEC (altitudes in the range of 250–400 km). The global tendency is that the decreased region expands to the east with increasing altitude and concentrates in the Southern hemisphere over the epicenter. These results indicate that the RMTNN method is applicable to the estimation of ionospheric electron density.

scholarly journals Daytime electron density at the F1-region in Europe during geomagnetic storms

2002 ◽  
Vol 20 (7) ◽  
pp. 1007-1021 ◽  
Author(s):  
D. Buresova ◽  
J. Lastovicka ◽  
D. Altadill ◽  
G. Miro
Keyword(s):  
Solar Activity ◽  
Electron Density ◽  
Geomagnetic Storm ◽  
Geomagnetic Storms ◽  
Middle Latitude ◽  
Lower Latitude ◽  
Ionospheric Disturbances ◽  
Activity Levels ◽  
Middle Latitudes

Abstract. This study attempts to demonstrate changes in the ionospheric F1-region daytime ionization during geomagnetic storms. The F1-region is explored using available data from several European middle latitude and lower latitude observatories and a set of geomagnetic storms encompassing a range of seasons and solar activity levels. The results of analysis suggest systematic seasonal and partly latitudinal differences in the F1-region response to geomagnetic storm. The pattern of the response of the F1-region at higher middle latitudes, a decrease in electron density, does not depend on the type of response of the F2-region and on solar activity. A brief interpretation of these findings is presented.Key words. Ionosphere (ionospheric disturbances; mid-latitude ionosphere)

scholarly journals Relationships between electron density, height and sub-peak ionospheric thickness in the night equatorial ionosphere

2006 ◽  
Vol 24 (5) ◽  
pp. 1343-1353 ◽  
Author(s):  
K. J. W. Lynn ◽  
T. J. Harris ◽  
M. Sjarifudin
Keyword(s):  
Electron Density ◽  
Equatorial Ionosphere ◽  
Electron Density Profile ◽  
Northern Australia ◽  
Ionospheric Storm ◽  
Equatorial Anomaly ◽  
Night Time ◽  
Slab Width ◽  
Maximum Electron Density ◽  
Made In

Abstract. The development and decay of the southern equatorial anomaly night-time peak in electron density as seen at a number of ionosonde reflection points extending from New Guinea and Indonesia into northern Australia was examined in terms of the characteristic rise and fall in height associated with the sunset ionisation-drift vortex at the magnetic equator. The observations relate to measurements made in November 1997. Following sunset, the ionospheric profile was observed to narrow as the maximum electron density increased during a fall in height that took the peak of the layer at Vanimo and Sumedang down to some 240 km. The fall was followed by a strong rise in which the electron density sub-peak profile expanded from a slab width (as given by POLAN) of 20 km to over 100km with no corresponding change in peak electron density. The post-sunset equatorial fall in height and associated changes in profile density and thickness continued to be seen with diminishing amplitude and increasing local time delay in moving from the anomaly peak at Vanimo to the southernmost site of observation at Townsville. Secondary events on a lesser scale sometimes occurred later in the night and may provide evidence of the multiple vortices suggested by Kudeki and Bhattacharyya (1999). Doppler measurements of vertical velocity as seen at Sumedang in Java are compared with the observed changes in electron density profile in the post-sunset period. The normal post-sunset variation in ionospheric parameters was disrupted on the night of 7 November, the night before a negative ionospheric storm was observed.

scholarly journals Global equivalent slab thickness model of the Earth’s ionosphere

2021 ◽  
Author(s):  
Norbert Jakowski ◽  
Mohammed Mainul Hoque
Keyword(s):  
Solar Activity ◽  
Electron Density ◽  
Total Electron Content ◽  
Local Time ◽  
Slab Thickness ◽  
Electron Content ◽  
Night Time ◽  
Total Electron ◽  
First Time ◽  
Model Approach

The shape of the vertical electron density profile is a result of production, loss and transportation of plasma in the Earth’s ionosphere. Therefore, the equivalent slab thickness of the ionosphere that characterizes the width of vertical electron density profiles is an important parameter for a better understanding of ionospheric processes under regular as well as under perturbed conditions. The equivalent slab thickness is defined by the ratio of the vertical total electron content over the peak electron density and is therefore easy to compute by utilizing powerful data sources nowadays available thanks to ground and space based GNSS techniques. Here we use peak electron density data from three low earth orbiting (LEO) satellite missions, namely CHAMP, GRACE and FORMOSAT-3/COSMIC, as well as total electron content data obtained from numerous GNSS ground stations. For the first time, we present a global model of the equivalent slab thickness (Neustrelitz equivalent Slab Thickness Model – NSTM). The model approach is similar to a family of former model approaches successfully applied for Total Electron Content (TEC), peak electron density NmF2 and corresponding height hmF2 at DLR. The model description focuses on an overall view of the behaviour of the equivalent slab thickness as a function of local time, season, geographic/geomagnetic location and solar activity on a global scale. In conclusion, the model agrees quite well with the overall observation data within a RMS range of 70 km. There is generally a good correlation with solar heat input that varies with local time, season and level of solar activity. However, under non-equilibrium conditions, plasma transport processes dominate the behaviour of the equivalent slab thickness. It is assumed that night-time plasmasphere-ionosphere coupling causes enhanced equivalent slab thickness values like the pre-sunrise enhancement. The overall fit provides consistent results with the mid-latitude bulge (MLB) of the equivalent slab thickness, described for the first time in this paper. Furthermore, the model recreates quite well ionospheric anomalies such as the Night-time Winter Anomaly (NWA) which is closely related to the Mid-latitude Summer Night Anomaly (MSNA) like the Weddell Sea Anomaly (WSA) and Okhotsk Sea Anomaly (OSA). Further model improvements can be achieved by using an extended model approach and considering the particular geomagnetic field structure.

scholarly journals Some theoretical of ionospheric storms at middle latitudes

1998 ◽  
Vol 41 (4) ◽  
Author(s):  
G. A. Mansilla ◽  
J. R. Manzano
Keyword(s):  
Numerical Method ◽  
Electron Density ◽  
Geomagnetic Storm ◽  
Continuity Equation ◽  
Geomagnetic Storms ◽  
Neutral Wind ◽  
Wind Effects ◽  
Middle Latitudes ◽  
Maximum Electron Density ◽  
Density Values

Neutral wind effects in the F2-region during geomagnetic storms are theoretically studied solving the continuity equation (with production and loss of electrons) by means of a numerical method. This study was made for storms with sudden commencement at different times of day and at different latitudes. The results show that the equatorward movements of neutral air produce either enhanced or depressed maximum electron density values which depend on the velocity of these winds when the perturbation occurs at diurnal hours. If the geomagnetic storm is present during the night, only enhanced values are observed.

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