Abstract
Introduction. It was previously reported that small-scale irregularities (SSI) in the polar ionosphere are elongated along the magnetic field and anisotropic in its cross-field direction. At the same time, the largest of the SSI cross-field axes tends to orient along the SSI drift direction. This is also indirectly confirmed for the midlatitude ionosphere, however, direct correlations of the SSI anisotropy and ionospheric drift directions in the middle latitudes are absent.Objective. The main objective of this work is a direct comparison of the experimental data of SSI shape with motion parameters of irregularities, which are measured at the same place (Moscow) at the same time. Previously, experimentally obtained values of the SSI cross-field anisotropy orientation in the midlatitude ionosphere were compared only with the neutral winds model.Materials and methods. A tomographic approach is used to determine the SSI anisotropy parameters by processing radio scintillation signals while overfly of several navigation satellites emitting on frequencies of 150 MHz and 400 MHz. Estimations of ratio between the ellipsoids axes and cross-field anisotropy orientations in the framework of SSI model in a form of magnetic field oriented ellipsoids with three different dimensions along and across the Earth's magnetic field are obtained. Irregularities parameters are obtained by selecting the model parameters when the calculated logarithm dispersion of the satellite signals relative amplitude while they orbiting is the closest to the experimentally obtained curve. Estimations of the velocity and drift direction of medium-scale irregularities (MSI) by using DPS-4 ionosonde data acquired while decameter-wave radar studies of ionosphere from the Earth's surface are obtained. The socalled "sky maps" presenting the energy distribution of scattered radio waves on incident angles are used. Simultaneous measurements of Doppler frequency shifts and incident angles of scattered waves allow obtaining estimations of three components of the medium-scale irregularities drift velocity.Results. A good correlation between the drift direction of medium-scale irregularities and cross-field anisotropy orientation of small-scale irregularities is found.Conclusion. The correlation between the cross-field anisotropy orientation of the elongated irregularities and their drift direction can be useful under conditions of the lack of information on ionospheric irregularities.
Highlights
Anisotropy of Ionospheric Irregularities Determined from the Amplitude of Satellite Signals at a Single Receiver / E
Anisotropy of Ionospheric Irregularities Determined from the Amplitude of Satellite Signals at a Singlereciver / E
Об ориентации поперечной анизотропии мелкомасштабных неоднородностей F-области в направлении дрейфа над Москвой в январе 2014 года / В
Summary
Для разных сред это различные характеристики, но общим является то, что эти параметры определяют коэффициент преломления используемых волн. В то же время наблюдаемые сигналы обратного рассеяния говорят о присутствии неоднородностей масштаба 10 1K 103 м [8] – так называемых мелкомасштабных неоднородностей (МН), сильно вытянутых вдоль магнитного поля Моделирование показывает [10], что параметры анизотропии существенно влияют на изменение дисперсии логарифма относительной амплитуды сигнала по мере прохождения спутника вблизи магнитного зенита. 3. Зависимость дисперсии логарифма относительной амплитуды сигнала и угла между вектором магнитного поля и направлением на спутник от географической широты спутника (Москва, 11.01.2014 00:25 UT). При анализе поля принимаемых на земле радиоволн для определения характеристик рассеивающих неоднородностей нужно обеспечить прием радиоволн только одной из двух поляризаций (обычно обыкновенной).
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