The high-latitude trough in ionospheric electron content

The electron content of the ionosphere is an important quantity which indicates overall ionization. It is measured by means of propagation effects on radio signals which penetrate the ionosphere. In Europe relevant investigations started after the launch of the first artificial satellites. Soon the necessity arose to organize international cooperation: the regional as well as the global geographical distribution of ionization parameters is important knowledge for any meaningful geophysical interpretation of ionization parameters. Despite the fact that international scientific Unions and Committees existed and had proven their usefulness and potential, private initiatives were taken to organize cooperation in the field of research based on transionospheric propagation effects. Only in 1971 three international groups joined together to form the "Beacon Satellite Group"as a "Working Party" of COSPAR. The "Beacon Satellite Group" still exists but is now a Working Group of URSI, the International Union for Radio Science. This contribution tries to summarize the European perspective with special emphasis on the long standing cooperation between the Istituto di Ricerca sulle Onde Elettromagnetiche (IROE) at Firenze and the Institut für Meteorologie und Geophysik of the University of Graz. Examples are given of important results.

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Assessing Global Ionosphere TEC Maps with Satellite Altimetry and Ionospheric Radio Occultation Observations

Sensors ◽

10.3390/s19245489 ◽

2019 ◽

Vol 19 (24) ◽

pp. 5489 ◽

Cited By ~ 2

Author(s):

Wei Li ◽

Longqiang Huang ◽

Shaocheng Zhang ◽

Yanju Chai

Keyword(s):

High Latitude ◽

Satellite Altimetry ◽

Radio Occultation ◽

Lower Latitude ◽

Electron Content ◽

Dual Frequency ◽

International Gnss Service ◽

Night Time ◽

Scaling Factors ◽

Total Electron

As global navigation satellite system (GNSS)stations are sparsely distributed in oceanic area, oceanic areas usually have lower precision than continental areas on a global ionosphere maps (GIM). On the other hand, space-borne observations like satellite altimetry (SA) and ionospheric radio occultation (IRO) have substantial dual-frequency observations in oceanic areas, which could be used for total electron content (TEC) retrieval. In this paper, the Jason-2 SA and Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) IRO products were used to assess the precision of IGS GIM products. Both the systematic biases and scaling factors between the international GNSS service (IGS) GIM TEC and space-borne TEC were calculated, and the statistical results show that the biases and the scaling factors obviously vary under different temporal-spatial conditions. This analysis shows that these differences are variable with diurnal and latitude factors, that is, the differences in biases during the day time are higher than those during the night time, and larger biases are experienced at lower latitude areas than at high latitude areas. The results also show that in the southern hemisphere middle-high latitude area and some other central oceanic areas, the space-borne TEC values are even higher than GIM TEC values. As the precision of space-borne TEC should be evenly distributed around different areas on Earth, it can be explain that the TEC in these areas is undervalued by the current GIM model, and the space-borne SA and IRO techniques could be used as complementary observations to improve the accuracy and reliability of TEC values in these areas.

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Study of mid-latitude nighttime enhancement in F-region electron density using tomographic images over the UK

Annales Geophysicae ◽

10.5194/angeo-21-2323-2003 ◽

2003 ◽

Vol 21 (12) ◽

pp. 2323-2328 ◽

Cited By ~ 15

Author(s):

R. S. Dabas ◽

L. Kersley

Keyword(s):

Electron Density ◽

Magnetic Activity ◽

Electron Content ◽

Equatorial Anomaly ◽

Tomographic Images ◽

F Region ◽

Electron Density Gradient ◽

Modeling And Forecasting ◽

Ionospheric Electron Content ◽

The Uk

Abstract. Nighttime enhancements in ionospheric electron content (IEC)/peak electron density (NmF2) have been studied by various workers in the equatorial anomaly and mid-latitude regions. Such studies give an idea about their enhancement over that location only. In the present study tomographic images over the UK, which give a latitudinal versus height distributions of ionospheric electron density in a much wider area, have been used to study the anomalous increases in nighttime F-region electron density at mid-latitudes. From the analysis of four seasonal representative months (November 1997, March, June and October 1998) data it was noted that the majority of the cases of nighttime enhancements were observed after local midnight, with a maximum between 03:00–04:00 LT in the month of November 1997. Enhancements were observed mostly between 45–50° N latitudes, and their positions are not affected by magnetic activity (Kp ) variations, whereas the separation between the mid-latitude trough and enhancement decreases with increases in magnetic activity. This finding shows that only the trough moves equatorward with the increase in magnetic activity. It is also noted that the electron density gradient from the trough to the enhancement increases with an increase in Kp. Results are discussed in terms of downward plasma transport from the protonosphere to the ionosphere and the nighttime neutral winds.Key words. Ionosphere (mid-latitude ionosphere; modeling and forecasting; instruments and techniques)

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