Propagation and application of waves in the ionosphere

Yeh, K. C.; Liu, C. H.

doi:10.1029/rg010i002p00631

Cited by 9 publications

(2 citation statements)

References 218 publications

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“…As stated in the seminal review paper by Yeh and Liu (1972), "one of the most outstanding features of a plasma is the change of its electromagnetic properties when it is under the influence of an external steady magnetic field". This is precisely the case of the ionosphere embedded in Earth's magnetic field, with the spitze phenomenon being one of these outstanding features.…”

Section: Discussionmentioning

confidence: 99%

Spitze Angle Changes during Rapid Geomagnetic Core Field Variation

et al. 2021

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The spitze phenomenon is an outstanding feature of electromagnetic wave propagation through the ionosphere. It consists in a ray path cusp that occurs between vertical propagation and a critical angle called the spitze angle. This angle that depends on the propagating wave frequency and on the geomagnetic field intensity and inclination, has gained renewed importance for its role in ionospheric modification by powerful radio wave experiments. Here we consider Earth's magnetic field secular variation on two distinctive timescales. First, the most drastic scenario considered is a polarity reversal. We present consequent changes in the spitze angle for three plausible transitional scenarios. Second, we track changes during the past 115 years based on geomagnetic field observations. Globally, we find that the spitze spatial variation is determined mainly by geomagnetic inclination with larger values for smaller inclinations. However, locally the spitze time variation differs from site to site and may depend on the evolution of either field intensity or inclination. Despite the long-term timescales considered, understanding the origin of the spitze spatio-temporal variations on various timescales is important from a physical point of view to unravel magnetized plasma phenomena.

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Section: Discussionmentioning

confidence: 99%

Spitze Angle Changes during Rapid Geomagnetic Core Field Variation

et al. 2021

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“…The ground range dependence on the geomagnetic field and the existence of the spitze phenomenon are just a couple of the 370 many features of electromagnetic wave propagation in a magnetized plasma. As stated in the seminal review paper by Yeh and Liu (1972), "one of the most outstanding features of a plasma is the change of its electromagnetic properties when it is under the influence of an external steady magnetic field". This is precisely the case of the ionosphere embedded in Earth's magnetic field.…”

Section: Discussionmentioning

confidence: 99%

Effects of Earth's magnetic field variation on high frequency wave propagation in the ionosphere

Fagre

Zossi

Yiğit

et al. 2019

Preprint

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Abstract. The ionosphere is an anisotropic, dispersive medium for the propagation of radio frequency electromagnetic waves due to the presence of the Earth's intrinsic magnetic field and free charges. The detailed physics of electromagnetic wave propagation through a plasma is more complex when it is embedded in a magnetic field. In particular, the ground range of waves reflecting in the ionosphere presents detectable magnetic field effects. Earth's magnetic field varies greatly, with the most drastic scenario being a polarity reversal. Here the spatial variability of the ground range is analyzed using numerical ray tracing under possible reversal scenarios. Pattern changes of the spitze, a cusp in the ray path closely related to the geomagnetic field, are also assessed. The ground range increases with magnetic field intensity and ray alignment with the field direction. For the present field, which is almost axial dipolar, this happens for Northward propagation at the magnetic equator, peaking in Indonesia where the intensity is least weak along the equator. A similar situation occurs for a prevailing equatorial dipole with Eastward ray paths at the corresponding magnetic equator that here runs almost perpendicular to the geographic equator. Larger spitze angles occur for smaller magnetic inclinations, and higher intensities. This is clearly observed for the present field and the dipole rotation scenario along the corresponding magnetic equators. For less dipolar configurations the ground range and spitze spatial variabilities become smaller scale. Overall, studying ionospheric dynamics during a reversal may highlight possible effects of dipole decrease which is currently ongoing.

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2017

Electromagnetic Wave Propagation, Radiation, and Scattering

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Propagation and application of waves in the ionosphere

Cited by 9 publications

References 218 publications

Spitze Angle Changes during Rapid Geomagnetic Core Field Variation

Spitze Angle Changes during Rapid Geomagnetic Core Field Variation

Effects of Earth's magnetic field variation on high frequency wave propagation in the ionosphere

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