AbstractStudies of the atmospheric tides and gravity waves at 70° N were made witt the EISCAT incoherent scatter radar on 3, 4 and 8 Aug 1988. This paper discusses measurements of the electron density and the field-aligned velocity, which is related to the horizontal meridional neutral-air wind. The phase of the 12 h oscillation in the neutral wind behaves smoothly with height on 3 Aug, but abrupt phase changes at 120 and 130 km are observed on 4 and 8 Aug, respectively. At lower heights the vertical wavelength of the 12 h oscillation is about 45 km, which corresponds to the (2,4) component of the semidiurnal tide. On 4 Aug the vertical wavelenght above 120 km altitude is about 200 km, which most probably indicates the dominance of the (2,2) mode. On the other hand, the phase above 130 km on 8 Aug and in the F-region on 4 Aug is nearly constant. The amplitude of the 12 h oscillation is quite variable from day to day, but it has a maximum at 100–110 km, which also speaks for the dominance of the (2,4) mode. In the F-region above 150 km, complex patterns of gravity waves are observed on all three days, which break up into discrete frequency ranges when subjected to filtering. The day-to-day variability of the 12 h oscillation may be due to interaction between the semidiurnal tide and the gravity waves.


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    Title :

    Observations of tides and gravity waves in the lower thermosphere at 70° N


    Contributors:

    Published in:

    Advances in Space Research ; 12 , 10 ; 107-110


    Publication date :

    1992-01-01


    Size :

    4 pages




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English