Analysis and results of low-frequency CW Rocket Propagation Experiments in the<i>D</i>region

Seliga, T. A.

doi:10.1029/ja073i021p06783

Cited by 7 publications

(4 citation statements)

References 15 publications

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“…At least three different rocket techniques have been used to measure electron density profiles. One technique, developed by Hall andFooks [1965, 1967] and Seliga [1966Seliga [ , 1968, utilized LF radio wave propagation from a ground transmitter to a rocket-borne receiver. In this method, the signal amplitude or scalar field o.f the LF wave was measured at the rocket.…”

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confidence: 99%

Comparisons of techniques for measurement of D‐region electron densities

Sechrist¹

1974

Radio Science

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This paper reviews the ground‐based and rocket techniques that are presently being used to determine electron density profiles in the ionospheric D region. Ground‐based techniques include VLF, LF, and MF sounding, differential absorption and differential phase using partial reflections, wave interaction, and incoherent scatter. Rocket techniques include differential absorption and Faraday rotation in association with high‐resolution dc probes calibrated by means of the radio measurements. The characteristics of the aforementioned techniques are presented, including time and height resolution, accuracy estimates, preferred height ranges, and problems encountered. Electron density profiles obtained with these techniques are presented for comparable solar zenith angles and undisturbed solar and geophysical conditions, and variances are described.

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confidence: 99%

Comparisons of techniques for measurement of D‐region electron densities

Sechrist¹

1974

Radio Science

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“…The total solar eclipse began at 16 Fig. 1 shows the totality path of the solar eclipse, as well as the great circle paths for the experiment configuration between NML and the VLF receivers in CO and UT (denoted as the NML-CO and NML-UT paths hereafter).…”

Section: Methodsmentioning

confidence: 99%

“…Using rocket experiments, Sears et al [13] directly investigated the variation of electron density in the D-region ionosphere during the 1966 solar eclipse in South America. However, previous studies of the solar eclipse using rocket sounding mostly measured the electron density at altitudes above ∼70 km [16]- [19] and the electron concentration below this altitude remains poorly investigated. More recently, a detailed modeling study of the solar eclipse in Europe on August 11, 1999 [14] revealed that the amplitude of VLF signals was usually enhanced for relatively short propagation paths (<2000 km) and diminished for relatively long propagation paths (>10000 km).…”

Section: Introductionmentioning

confidence: 99%

VLF Measurements and Modeling of the D-Region Response to the 2017 Total Solar Eclipse

Marshall

Kero

et al. 2019

IEEE Trans. Geosci. Remote Sensing

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In this paper, we report measurements in Colorado and Utah of the disturbed very-low-frequency (VLF) signals from the NML Navy transmitter in North Dakota during the 2017 solar eclipse. Using an occultation mask of solar fluxes together with detailed chemistry and VLF propagation simulations, we quantify the D-region response to the eclipse, in terms of electron density variation, as well as the expected signatures of VLF transmitter signals. The VLF measurements, including an anomalous amplitude enhancement recorded in UT, can be quantitatively explained using the Wait and Spies ionospheric profile with a sharpness parameter of β = 0.3 km −1 above ∼55 km and an increase in the D-region ionosphere height of h 8 km. This sharpness parameter is consistent with previously reported rocket measurements and first-principles calculations. The best-fit results suggest a reduction of D-region electron density by ∼90% during the eclipse in the D-region, implying an occultation of Lyman-α by nearly 99%. This finding agrees with detailed calculations of time-dependent obscuration factors utilizing the He 30.4-nm images from Solar Dynamics Observatory as a proxy for the distribution of Lyman-α across the solar disk and limb. Moreover, the present results show that subionospheric VLF propagation is sensitive to the sharpness parameter of the electron density profile in the D-region. Previously reported first-principles simulations have shown that the sharpness parameter is mostly controlled by the background concentration of minor neutral species. Thus, the VLF technique can be likely used to remotely sense these neutral species at and below the effective reflection altitudes of VLF waves. IndexTerms-D-region ionosphere, earth-ionosphere waveguide, finite-difference frequency domain (FDFD), ionosphere, ionosphere chemistry, Lyman-α radiation, solar eclipse, subionospheric very-low-frequency (VLF) remote sensing, transmitter, VLF. Manuscript

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“…Further details on ionospheric layer profiling using rocket beacon signals are described by Bernhardt et al. (1993), Evans (1977), Friedman (1959), Jackson (1954), Maeda (1970), Seliga, 1968, and Smith and Gilchrest (1984).…”

Section: Introductionmentioning

confidence: 99%

Global Simulations of Multi‐Frequency HF Signal Absorption for Direct Observation of Middle Atmosphere Temperature and Composition

2023

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This paper presents the first numerical study on a new concept for the direct measurement of D‐region absorption in the high‐frequency (HF) band. Numerical simulations based on the Appleton‐Hartree and Garrett equations of refractive index are presented. Electron temperature as a result of HF radio pumping of the ionosphere is included in the calculations using proper numerical formulation. Both O‐ and X‐mode radio wave polarizations are taken into consideration. A global map of HF absorption in the northern hemisphere is calculated. Detailed calculations of HF radio wave absorption as it propagates through the lower atmosphere are presented. The effect of several parameters on the amount of absorption is calculated. The best frequencies to be used for the purpose of this study are discussed. A machine learning model is developed and the capability of the model in estimation of D and E‐region constituents includes N2, O, O2, as well as T and Ne is examined. Such a technique can also lead to global mapping of HF absorption and improve OTHR (over‐the‐horizon‐radar) performance.

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Analysis and results of low-frequency CW Rocket Propagation Experiments in theDregion

Cited by 7 publications

References 15 publications

Comparisons of techniques for measurement of D‐region electron densities

Comparisons of techniques for measurement of D‐region electron densities

VLF Measurements and Modeling of the D-Region Response to the 2017 Total Solar Eclipse

Global Simulations of Multi‐Frequency HF Signal Absorption for Direct Observation of Middle Atmosphere Temperature and Composition

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