Abstract Calibration observations made with the Westerbork Synthesis Radio Telescope (6.6° E, 52.9° N) in the years 1980–1987 at 49 and 92 cm wavelength, have been used to study the climatology of Medium Scale Travelling Ionospheric Disturbances, MSTIDs. The occurrence and amplitude of MSTIDs show a marked semidiurnal variation during most of the year with a primary maximum around noon and a secondary maximum around midnight. Only during summer this typical behaviour is absent. In years of high solar activity the overall occurrence and amplitude of MSTIDs were significantly larger than in years with lower solar activity. Most of the observed MSTIDs had (apparent) periods in between 8 and 20 minutes, i.e. (apparent) periods smaller than the Brunt-Väisälä period at ionospheric heights (∼ 12–16 min) were frequently observed. The average observed period of MSTIDs reached a maximum before local noon, a minimum during the night and showed a dip just after noon. We explain this variation by the effect of the neutral background wind upon the waves. The average period of MSTIDs varied also with the azimuth of the line of sight. This is related to the directional sensitivity of the instrument used to observe MSTIDs. No correlation between MSTID related quantities and geomagnetic activity was found.


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    Titel :

    Climatology of medium scale travelling ionospheric disturbances from radio interferometric observations


    Beteiligte:

    Erschienen in:

    Advances in Space Research ; 12 , 6 ; 211-214


    Erscheinungsdatum :

    1991-01-01


    Format / Umfang :

    4 pages




    Medientyp :

    Aufsatz (Zeitschrift)


    Format :

    Elektronische Ressource


    Sprache :

    Englisch