AbstractThe ratio of daytime and nighttime values of the foF2 critical frequency is analyzed on the basis of the data of 35 ionospheric stations of the eastern hemisphere and 7 stations of the western hemisphere. The analysis confirms the results of Danilov [Danilov, A.D. Variations in the ratio of nighttime and daytime critical frequencies of the F2 layer. Geomagn. Aeronomy, 47 (6), 551–561 (in Russian) 2007; Danilov, A.D. Time and spatial variations in the ratio of nighttime and daytime critical frequencies of the F2 layer, J. Atmos. Sol-Terr. Phys. 70, 1201–1212, 2008.] that after about 1980, a systematic behavior of this ratio with time is observed: an increase with time (a positive trend) or a decrease with time (a negative trend). The sign of this trend is shown to be governed by the signs of the magnetic declination D and magnetic inclination I at the given ionospheric station. This fact makes it possible to assume that the above indicated trend is caused by long-term variations in the zonal component Vny of the horizontal wind in the thermosphere, the latter component contributing into the vertical drift velocity W.


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    Title :

    Time and spatial variations of the foF2(night)/foF2(day) values


    Contributors:

    Published in:

    Advances in Space Research ; 43 , 11 ; 1786-1793


    Publication date :

    2008-08-18


    Size :

    8 pages




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English





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