Midlatitude sporadic-E episodes viewed by L-band split-spectrum InSAR

Sporadic-E (Es) is a layer of ionization that irregularly appears within the E region of the ionosphere and is known to generate an unusual propagation of very high frequency waves over long distances. The detailed spatial structure of Es remains unclear due to the limited spatial resolution in the...

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Bibliographic Details
Published in:Earth, planets, and space planets, and space, 2017-12, Vol.69 (1), p.1-10, Article 175
Main Authors: Furuya, Masato, Suzuki, Takato, Maeda, Jun, Heki, Kosuke
Format: Article
Language:English
Subjects:
2. Aeronomy
Dispersive media
E region
Earth and Environmental Science
Earth Sciences
Geology
Geophysics/Geodesy
GNSS and SAR Technologies for Atmospheric Sensing
Interferometric synthetic aperture radar
Interferometry
Ionization
Ionosphere
Ionospheric propagation
Iron
Magnesium
Nitric oxide
Radar
Refractive index
Refractivity
Spatial resolution
Split-spectrum method
Sporadic-E
Synthetic aperture radar
Synthetic aperture radar interferometry
Total electron content
Wave propagation
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Summary:Sporadic-E (Es) is a layer of ionization that irregularly appears within the E region of the ionosphere and is known to generate an unusual propagation of very high frequency waves over long distances. The detailed spatial structure of Es remains unclear due to the limited spatial resolution in the conventional ionosonde observations. We detect midlatitude Es by interferometric synthetic aperture radar (InSAR), which can clarify the spatial structure of Es with unprecedented resolution. Moreover, we use the range split-spectrum method (SSM) to separate dispersive and nondispersive components in the InSAR image. While InSAR SSM largely succeeds in decomposing into dispersive and nondispersive signals, our results indicate that small-scale dispersive signals due to the total electron content anomalies are accompanied by nondispersive signals with similar spatial scale at the same locations. We also examine the effects of higher-order terms in the refractive index for dispersive media. Both of these detected Es episodes indicate that smaller-scale dispersive effects originate from higher-order effects. We interpret that the smaller-scale nondispersive signals could indicate the emergence of nitric oxide (NO) generated by the reactions of metals, Mg and Fe, with nitric oxide ion (NO + ) during the Es.
ISSN:1880-5981
1880-5981
DOI:10.1186/s40623-017-0764-6