Trends in the critical frequency foF2 at stations of the Northern and Southern hemispheres

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Abstract

A search for long-term trends in the F2 layer critical frequency foF2 is performed based on vertical sounding observations at three stations of the Northern Hemisphere (Juliusruh, Boulder, and Moscow) and three stations of the Southern Hemisphere (Townsville, Hobart, and Canberra). A method developed and extensively described by the authors is used. The data for two winter months in each hemisphere for five near-noon LT moments were analyzed. Three solar activity (SA) proxies (F30, Ly-α, and MgII) were used to eliminate SA effects. Negative trends are obtained for all considered situations (station, month, LT moment, SA proxy). The trends agree well with each other both if stations of the Northern and Southern hemispheres are compared individually or in aggregate.

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About the authors

A. D. Danilov

Institute of Applied Geophysics

Author for correspondence.
Email: adanilov99@mail.ru
Russian Federation, Moscow

A. V. Konstantinova

Institute of Applied Geophysics

Email: adanilov99@mail.ru
Russian Federation, Moscow

N. A. Berbeneva

Moscow State University

Email: adanilov99@mail.ru

Physical Faculty 

Russian Federation, Moscow

References

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Supplementary files

Supplementary Files
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2. Fig. 1. Examples of changes in ΔfoF2 over time for Moscow station in January.

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3. Fig. 2. Examples of changes in ΔfoF 2 over time for Moscow station in February.

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4. Fig. 3. Examples of ΔfoF2 changes over time for Boulder station in January.

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5. Fig. 4. Examples of ΔfoF2 changes over time for Boulder station in February.

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6. Fig. 5. Examples of ΔfoF2 changes over time for Townsville station in June.

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7. Fig. 6. Examples of ΔfoF2 changes over time for Townsville station in July.

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8. Fig. 7. Examples of ΔfoF2 changes over time for Hobart station in June.

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9. Fig. 8. Examples of ΔfoF2 changes over time for Hobart station in July.

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10. Fig. 9. Examples of ΔfoF2 changes over time for Canberra station in June.

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11. Fig. 10. Change in ΔfoF2 over time for Canberra station in July.

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12. Fig. 11. Examples of the dependence of foF2 on SA indices for two time intervals.

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