Electron density at F1-layer heights in the last solar minimum (2007–2009)

We present the results of the analysis of annual variations in daily electron density (N) at heights 140–160 km for the last solar minimum (2007–2009) obtained from digisonde measurements at the ionospheric station Irkutsk (52 °N, 104 °E). New coefficients of the known semi-empirical model (SEM) describing the connection between N and thermospheric characteristics are calculated to identify regularities of these variations. We have revealed that a characteristic feature of the annual N variations during the solar minimum is a change in their phase by 180° in a relatively narrow altitude interval (170–180 km). These results and the new SEM coefficients are original and important for atmospheric and ionospheric physics.

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Electron density in the F1 layer over Norilsk in 2007–2014

Solnechno-Zemnaya Fizika ◽

10.12737/szf-52201915 ◽

2019 ◽

Vol 5 (2) ◽

pp. 124-128

Author(s):

Галина Кушнаренко ◽

Galina Kushnarenko ◽

Ольга Яковлева ◽

Olga Yakovleva ◽

Галина Кузнецова ◽

...

Keyword(s):

Solar Activity ◽

Electron Density ◽

Solar Minimum ◽

Annual Variation ◽

Data Approximation ◽

Annual Variations ◽

Ionospheric Station ◽

Different Seasons ◽

Semi Empirical ◽

Maximum Solar Activity

We report the results of the analysis of annual variations in daily electron density (N) for various solar activity conditions — minimum, rise, and maximum (2007–2014) — obtained from digisonde measurements at the ionospheric station Norilsk (69.4° N, 88.1° E). New coefficients of the known semi-empirical model (SEM) describing the connection between N and thermosphere characteristics are calculated to identify regularities of these variations exactly at Norilsk station. The height changes of annual variations in the noon electron density N are obtained in the F1 region (120–200 km). The experimental data approximation describes N quite satisfactorily at these heights in the daytime of different seasons under different solar activity conditions. It is shown that in the years of solar minimum at all heights of the F1 layer the tendency remains for maximum N in summer and for minimum N in winter. In later years and in the year of maximum solar activity, a characteristic feature of the behavior of N is the change in the phase of the annual variation by 180° in the range of heights from 170 to180 km: maximum N is observed in winter; and minimum, in summer.

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Electron density in the F1 layer over Norilsk in 2007–2014

Solar-Terrestrial Physics ◽

10.12737/stp-52201915 ◽

2019 ◽

Vol 5 (2) ◽

pp. 109-112

Author(s):

Галина Кушнаренко ◽

Galina Kushnarenko ◽

Ольга Яковлева ◽

Olga Yakovleva ◽

Галина Кузнецова ◽

...

Keyword(s):

Solar Activity ◽

Electron Density ◽

Solar Minimum ◽

Annual Variation ◽

Data Approximation ◽

Annual Variations ◽

Ionospheric Station ◽

Different Seasons ◽

Semi Empirical ◽

Maximum Solar Activity

We report the results of the analysis of annual variations in daily electron density (N) for various solar activity conditions — minimum, rise, and maximum (2007–2014) — obtained from digisonde measurements at the ionospheric station Norilsk (69.4° N, 88.1° E). New coefficients of the known semi-empirical model (SEM) describing the connection between N and thermosphere characteristics are calculated to identify regularities of these variations exactly at Norilsk station. The height changes of annual variations in the noon electron density N are obtained in the F1 region (120–200 km). The experimental data approximation describes N quite satisfactorily at these heights in the daytime of different seasons under different solar activity conditions. It is shown that in the years of solar minimum at all heights of the F1 layer the tendency remains for maximum N in summer and for minimum N in winter. In later years and in the year of maximum solar activity, a characteristic feature of the behavior of N is the change in the phase of the annual variation by 180° in the range of heights from 170 to180 km: maximum N is observed in winter; and minimum, in summer.

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Behavior of electron density in the ionosphere over Norilsk during the period of declining solar activity

Solar-Terrestrial Physics ◽

10.12737/stp-72202107 ◽

2021 ◽

Vol 7 (2) ◽

pp. 70-73

Author(s):

Olga Yakovleva ◽

Galina Kushnarenko ◽

Galina Kuznetsova

Keyword(s):

Experimental Data ◽

Solar Activity ◽

Electron Density ◽

Empirical Model ◽

High Latitude ◽

Geomagnetic Disturbances ◽

Ionospheric Layer ◽

Annual Variations ◽

Latitude Station ◽

Semi Empirical

We report the results of approximation of electron density Ne array obtained with a digisonde at the high-latitude station Norilsk (69.40° N, 88.10° E) during years of declining solar activity (2003–2006). The calculations are made using the author's semi-empirical model with new coefficients calculated specifically for the station Norilsk. We obtain altitudinal changes of annual variations in daily Ne at heights of the ionospheric layer F1 (120–200 km). Approximation of experimental data describes Ne quite satisfactorily at these heights. Nevertheless, there are periods with quite pronounced deviations of model values from the experiment. The presence of significant geomagnetic disturbances during these periods is probably one of the reasons for such deviations.

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Behavior of electron density in the ionosphere over Norilsk during the period of declining solar activity

Solnechno-Zemnaya Fizika ◽

10.12737/szf-72202107 ◽

2021 ◽

Vol 7 (2) ◽

pp. 77-80

Author(s):

Olga Yakovleva ◽

Galina Kushnarenko ◽

Galina Kuznetsova

Keyword(s):

Experimental Data ◽

Solar Activity ◽

Electron Density ◽

Empirical Model ◽

High Latitude ◽

Geomagnetic Disturbances ◽

Ionospheric Layer ◽

Annual Variations ◽

Latitude Station ◽

Semi Empirical

We report the results of approximation of electron density Ne array obtained with a digisonde at the high-latitude station Norilsk (69.40° N, 88.10° E) during years of declining solar activity (2003–2006). The calculations are made using the author's semi-empirical model with new coefficients calculated specifically for the station Norilsk. We obtain altitudinal changes of annual variations in daily Ne at heights of the ionospheric layer F1 (120–200 km). Approximation of experimental data describes Ne quite satisfactorily at these heights. Nevertheless, there are periods with quite pronounced deviations of model values from the experiment. The presence of significant geomagnetic disturbances during these periods is probably one of the reasons for such deviations.

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A Semi-Empirical Model for Predicting Frost Properties

Processes ◽

10.3390/pr9030412 ◽

2021 ◽

Vol 9 (3) ◽

pp. 412

Author(s):

Shao-Ming Li ◽

Kai-Shing Yang ◽

Chi-Chuan Wang

Keyword(s):

Thermal Conductivity ◽

Linear Programming ◽

Numerical Model ◽

Empirical Model ◽

Quantitative Method ◽

Predictive Ability ◽

Dimensionless Temperature ◽

Crystal Shape ◽

Proposed Model ◽

Semi Empirical

In this study, a quantitative method for classifying the frost geometry is first proposed to substantiate a numerical model in predicting frost properties like density, thickness, and thermal conductivity. This method can recognize the crystal shape via linear programming of the existing map for frost morphology. By using this method, the frost conditions can be taken into account in a model to obtain the corresponding frost properties like thermal conductivity, frost thickness, and density for specific frost crystal. It is found that the developed model can predict the frost properties more accurately than the existing correlations. Specifically, the proposed model can identify the corresponding frost shape by a dimensionless temperature and the surface temperature. Moreover, by adopting the frost identification into the numerical model, the frost thickness can also be predicted satisfactorily. The proposed calculation method not only shows better predictive ability with thermal conductivities, but also gives good predictions for density and is especially accurate when the frost density is lower than 125 kg/m3. Yet, the predictive ability for frost density is improved by 24% when compared to the most accurate correlation available.

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