Simultaneous HF measurements of E- and F-region Doppler velocities at large flow angles

• Main Authors: R. A. Makarevitch, F. Honary, A. V. Koustov
• Format: Article
• Language: English
• Published: Copernicus Publications 2004-04-01
• Series: Annales Geophysicae
• Online Access: https://www.ann-geophys.net/22/1177/2004/angeo-22-1177-2004.pdf

Data collected by the CUTLASS Finland HF radar are used to illustrate the significant difference between the cosine component of the plasma convection in the F-region and the Doppler velocity of the E-region coherent echoes observed at large flow angles. We show that the E-region velocity is ~5 times smaller in magnitude and rotated by ~30° clockwise with respect to convection in the F-region. Also, measurements at flow angles larger than 90° exhibit a completely new feature: Doppler velocity increase with the expected aspect angle and spatial anticorrelation with the backscatter power. By considering DMSP drift-meter measurements we argue that the difference between F- and E-region velocities cannot be interpreted in terms of the convection change with latitude. The observed features in the velocity of the E-region echoes can be explained by taking into account the ion drift contribution to the irregularity phase velocity as predicted by the linear fluid theory.<br><br> <b>Key words.</b> Ionosphere (auroral ionosphere; ionospheric irregularities; plasma convection)