An improved technique to determine neutral winds in the auroral mesosphere using the EISCAT VHF incoherent scatter radar

• Published in: Journal of atmospheric and solar-terrestrial physics 1997, Vol.59 (15), p.1909-1918
• Main Author: Collis, P.N.
• Format: Article
• Language: English
• ISSN: 1364-6826; 1879-1824
• DOI: 10.1016/S1364-6826(97)00030-8

The EISCAT VHF radar can be operated to obtain simultaneous measurements of the zonal and meridional components of the mesospheric neutral wind with an altitude resolution of the order of 1 km. We describe the application of this technique and introduce some initial results from an interval near the autumn equinox. These include 21 hours of continuous observations of the zonal wind in the mesosphere, showing predominantly semi-diurnal tidal characteristics in the observed altitude range of 75–95 km. Mean winds, and the amplitude and phase of the 12-h zonal component as a function of altitude, are deduced. Significant differences from published climatological results are found. Evidence of shorter period wave activity is also apparent. The vertical wind component is demonstrated to have a negligible effect on the derived horizontal velocities in this data set, using 5-min averages. Clockwise rotation of the horizontal wind vector with increasing altitude, with a vertical wavelength of 8–12 km, is a fundamental property of the wind field at these heights.