Cusp Type Anomalies in Variable Frequency Ionospheric Records

Munro, GH; Heisler, L.H.

doi:10.1071/ph560343

Cited by 70 publications

(44 citation statements)

References 10 publications

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“…The cusp generally appears first on the ordinary ray trace and later on the extraordinary ray. The origin of these cusps is explained in an accompanying paper (Munro and Heisler 1956). …”

Section: Variable Frequency Recordsmentioning

confidence: 95%

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Divergence of Radio Rays in the Ionosphere

Munro¹,

Heisler²

1956

Aust. J. Phys.

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SummaryTravelling disturbance manifestations on ionosonde records usually occur at different times on the "0" and "x" traces. It is shown that this is due to the divergence of the ordinary and the extraordinary rays in the Earth's magnetic meridian plane and that the sense of this time difference, therefore, gives a direct indication of the sense of the north-south component of movement of the disturbance. Furthermore, where the direction and speed of travel of a disturbance can also be determined from spaced station observations, the act,ual separation of reflection points of the 0-and the x-rays can be deduced. At Sydney, N.S.W. (33 0 52' S., 151" 11' E.) this is of the order of 30 km at the height of maximum ionization of the F 2 region. On h't records the corresponding time difference observed includes a component due to the vertical separation of reflection points if the front of the disturbance is not vertical. From records of this type taken at three spaced stations the horizontal component may be determined directly. Examination of some 430 such observations taken over a period of 4 years confirms the variation of the time difference with direction of travel predicted by theory, and also indicates the consistent presence of a forward tilt in the front of disturbances.The theoretical relation between the horizontal and vertical separation is then used to determine the slope of front of disturbances. It is found to have a mean value varying from 65 0 to the horizontal for disturbances travelling northward to a minimum of 51 0 for those travelling 120 0 E. of N.

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“…The cusp generally appears first on the ordinary ray trace and later on the extraordinary ray. The origin of these cusps is explained in an accompanying paper (Munro and Heisler 1956). …”

Section: Variable Frequency Recordsmentioning

confidence: 95%

“…It has been shown elsewhere (Munro and Heisler 1956) that, although the virtual height change of a cusp is great (of the order of a hundred kilometres), the actual height change is much less (of the order of tens of kilometres) so that this constancy is not unexpected.…”

Section: Erg Enc E Of Ra Diomentioning

confidence: 97%

Divergence of Radio Rays in the Ionosphere

Munro¹,

Heisler²

1956

Aust. J. Phys.

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“…This probably means that the tilt is in the neutral disturbance itself and is not principally a result of charged particle interaction with the geomagnetic field. Other work by Munro and Heisler (1956a) shows that such tiltedfront TID's propagate horizontally over large distances, and Munro (1958) has measured the seasonal variation in number a~?-direction of such naturally occurring disturbances.…”

Section: Introductionmentioning

confidence: 97%

The Origin and Propagation of Acoustic?Gravity Waves Ducted in the Thermosphere

Wickersham¹

1968

Aust. J. Phys.

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SummaryThe theory of acoustic-gravity waves in a thermoclinal atmosphere shows that damping decreases as the thermal gradient increases. If the thermal gradient is large enough it offsets the increase in amplitude caused by upward propagation into a region of decreasing ambient density and the motion is completely undamped, neglecting viscosity. Thus it appears that long distance propagation can occur in the principal duct at 150 km altitude, where the thermal gradient is almost large enough to eliminate nonviscous damping.It is shown that thermal perturbation of the principal duct by the long winter-solstice sunrise in the polar regions is a source of ducted gravity waves consistent with the seasonal variations in directions of travelling ionospheric disturbances (TID's) observed in Australia.The observed tilts of TID's are compared with theory and can be used to determine the period of a disturbance. The effect of ionospheric charge equilibration is discussed briefly, and a leaky· duct gravity wave model is proposed which reconciles the observations of tilted wave fronts and long distance propagation.

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“…Еще в середине прошлого века было установлено [Munro, Heisler, 1956], что появление серпообразных особенностей на ионограммах связано с прохожде-нием ПИВ, которые приводят к образованию гори-зонтальных градиентов электронной концентрации ионосферы и, соответственно, к боковым отражениям лучей при радиозондировании.…”

Section: Introductionunclassified

Numerical synthesis of ionograms in horizontally inhomogeneous ionosphere on the basis of compound parabolic layer model

Ларюнин¹,

Laryunin

2016

Solnechno-Zemnaya Fizika

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Аннотация. Появление серпообразных особен-ностей на ионограммах связано с прохождением перемещающихся ионосферных возмущений (ПИВ), которые приводят к образованию горизонтальных градиентов электронной концентрации ионосферы и, соответственно, к боковым отражениям лучей при радиозондировании. Обсуждаются возможности сокращения времени расчета при численном синтезе ионограмм вертикального зондирования. Предложена модель комбинированного параболического слоя, которая позволяет использовать в расчетах аналити-ческие выражения для траекторных характеристик. Исследованы изменения формы трека ионограммы, к которым приводит варьирование параметров ПИВ.Ключевые слова: ионосфера, вертикальное зон-дирование, ионограмма.Abstract. Characteristic U-shaped traces (cusps) on ionograms have been identified as off-angle echoes from sloping electron density contours caused by the presence of traveling ionospheric disturbances (TIDs). Dynamics of the cusps is associated with horizontal drift of the disturbances.A potential for reducing calculation time in numerical synthesis of vertical ionograms is under discussion.Since numerical ray tracing is expensive in terms of computer time, we have developed simplified formulation for this study. The suggested model of compound parabolic layer allows us to analytically calculate ray paths. Changes in the shape of the ionogram cusp caused by varying TID characteristics are examined.

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Cusp Type Anomalies in Variable Frequency Ionospheric Records

Cited by 70 publications

References 10 publications

Divergence of Radio Rays in the Ionosphere

Divergence of Radio Rays in the Ionosphere

The Origin and Propagation of Acoustic?Gravity Waves Ducted in the Thermosphere

Numerical synthesis of ionograms in horizontally inhomogeneous ionosphere on the basis of compound parabolic layer model

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