The Riometer-A Device for the Continuous Measurement of Ionospheric Absorption

Little, C. G.; Leinbach, H.

doi:10.1109/jrproc.1959.287299

Cited by 168 publications

(95 citation statements)

References 3 publications

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“…[6] The riometer utilizes the absorption of cosmic radio noise by the ionosphere [Little and Leinbach, 1959] to measure the enhancement of the D-region electron concentration by energetic charged particle precipitation [Stauning, 1996]. The riometer technique compares the strength of the cosmic radio noise signal received on the ground to the normal sidereal variation referred to as the quiet-day curve to produce the cosmic noise absorption.…”

Section: Methodsmentioning

confidence: 99%

Improved dynamic geomagnetic rigidity cutoff modeling: Testing predictive accuracy

et al. 2007

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[1] In the polar atmosphere, significant chemical and ionization changes occur during solar proton events (SPEs). The access of solar protons to this region is limited by the dynamically changing geomagnetic field. In this study, we have used riometer absorption observations to investigate the accuracy of a model to predict K p -dependent geomagnetic rigidity cutoffs, and hence the changing proton fluxes. The imaging riometer at Halley, Antarctica is ideally situated for such a study, as the rigidity cutoff sweeps back and forth across the instrument's field of view, providing a severe test of the rigidity cutoff model. Using observations from this riometer during five solar proton events, we have confirmed the basic accuracy of this rigidity model. However, we find that the model can be improved by setting a lower K p limit (i.e., K p = 5 instead of 6) at which the rigidity modeling saturates. We also find that, for L > 4.5, the apparent L-shell of the beam moves equatorward. In addition, the Sodankylä Ion and Neutral Chemistry (SIC) model is used to determine an empirical relationship between integral proton precipitation fluxes and nighttime ionosphere riometer absorption, in order to allow consideration of wintertime SPEs. We find that during the nighttime, the proton flux energy threshold is lowered to include protons with energies of >5 MeV in comparison with >10 MeV for the daytime empirical relationships. In addition, we provide an indication of the southern and northern geographic regions inside which SPEs play a role in modifying the neutral chemistry of the stratosphere and mesosphere.Citation: Clilverd, M. A., C. J. Rodger, T. Moffat-Griffin, and P. T. Verronen (2007), Improved dynamic geomagnetic rigidity cutoff modeling: Testing predictive accuracy,

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Section: Methodsmentioning

confidence: 99%

Improved dynamic geomagnetic rigidity cutoff modeling: Testing predictive accuracy

et al. 2007

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“…The winter anomaly, which is an increase in absorption in the midlatitude ionosphere during winter, has been studied by Thomas [1961] and Sato [1980], amongst other researchers. Measurements of the absorption of extraterrestrial radio waves by the ionosphere have also been made by several researchers, as a method for studying the structure and dynamics of the ionosphere [Little and Leinbach, 1959;Detrick and Rosenberg, 1990], particularly in the auroral regions [Basler, 1963;Hargreaves, 1969].…”

Section: Introductionmentioning

confidence: 99%

Semiempirical Model for Ionospheric Absorption based on the NRLMSISE‐00 atmospheric model

Pederick

Cervera

2014

Radio Science

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The strength of high‐frequency radio signals, when refracted by the ionosphere, can be strongly influenced by ionospheric absorption. Accurate modeling of the amount of this absorption is a vital part of many studies of radio waves propagating in the ionosphere. We have developed a new, flexible model of ionospheric absorption, the Semiempirical Model for Ionospheric Absorption based on the NRLMSISE‐00 atmospheric model (SiMIAN). This article describes the methods and formulae used by SiMIAN, a comparison of SiMIAN with an older absorption model, and validation work performed by simulating the power returned in vertical incidence soundings of the ionosphere and comparing the results with real soundings.

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“…These evidences have also been identified by riometric observation of the galactic radio noise (Little et al 1959, Reid et al 1959, Hultqvist 1959 and by observation of VHF polar circuits (Bailey 1957(Bailey , 1959.…”

Section: Introductionmentioning

confidence: 66%

Characteristics of Solar Energetic Particles which Excite Polar-Cap Blackouts

Sinno

1961

J. geomagn. geoelec

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Ejection and prapagation of the particles which excite abnormal ionization in the polar upper atmosphere are investigated from some statistical considerations on ionospheric data f-min and cosmic radio observation by riometer.Relations between the flares and the polar-cap blackouts insist the trapping of particles into the cloud which would be responsible for the geomagnetic disturbances;that is, a part of the energetic particles ejecting from the flare propagate with relativistic velocity in interplanetary space along the twisted solar magnetic line of force extending to the earth and excite the S-type polarcap blackouts having sudden onset within a few hours after flare; on the other hand, another part of the energetic particles ejecting from the flare is trapped into the cloud and is carried with rather low velocity, then the particles would reach the earth by leaking from the cloud and excite the G-type polar-cap blackouts having gradual onset about 10 hours before commencement of geomagnetic storms.

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The Riometer-A Device for the Continuous Measurement of Ionospheric Absorption

Cited by 168 publications

References 3 publications

Improved dynamic geomagnetic rigidity cutoff modeling: Testing predictive accuracy

Improved dynamic geomagnetic rigidity cutoff modeling: Testing predictive accuracy

Semiempirical Model for Ionospheric Absorption based on the NRLMSISE‐00 atmospheric model

Characteristics of Solar Energetic Particles which Excite Polar-Cap Blackouts

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