Abstract Neutral winds can be deduced from E-region incoherent scatter measurements of the ion velocity, in conjunction with measurements of the electric field and knowledge of the ion-neutral collison frequency. Measurement techniques and methods used to derive lower-thermospheric neutral winds are presented and compared. The sensitivity of the results to the ion-neutral collision frequency is discussed. Observations of the lower thermosphere at mid- and high latitudes show that neutral dynamics are influenced by both tidal oscillations and magnetospheric forcing. The tidal results obtained using Mesosphere-Stratosphere-Troposphere (MST), Medium-Frequency (MF), meteor, and Incoherent Scatter (IS) radars are generally consistent, and show the dominance of semidiurnal oscillations. At Chatanika, Alaska (65°N, 65Λ), the average summer semidiurnal oscillation reaches a peak amplitude of approximately 60 m/s at 110-km altitude. Recent measurements obtained using the IS radar at Søndre Strømfjord, Greenland (67°N, 74.5Λ), show a similar strong semidiurnal component in the neutral winds. The response of the neutral winds to magnetospheric forcing is in qualitative agreement with the results of three-dimensional global model simulations of the thermosphere, which predict deviations in the normal flows as a result of frictional coupling to the convecting ions. Auroral zone measurements at Chatanika show that the response is strongest in the morning sector, where enhanced zonal flow is detected during geomagnetically disturbed conditions. Recent polar cap measurements at Sondrestrom likewise show a response to enhanced ion convection during a highly disturbed interval.


    Access

    Check access

    Check availability in my library

    Order at Subito €


    Export, share and cite



    Title :

    Lower-thermospheric neutral winds at high latitude determined from incoherent scatter measurements: a review of techniques and observations


    Contributors:

    Published in:

    Advances in Space Research ; 10 , 6 ; 261-275


    Publication date :

    1989-01-01


    Size :

    15 pages




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English