Printed in Great Britain. Perpmon Press Ltd. Field-perpendicular nd field-aligned plasma flows observed by EISCAT during a prolonged period of northward IMF

• Main Authors: A. D. Farmer, M. Lockwood, R. B. Horne, B. J. I. Bromage, K. S. C. Freeman
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1984
• Subjects: Tromso; EISCAT
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.695.461; http://www.eiscat.rl.ac.uk/Members/mike/publications/pdfs/1984/14_Farmeretal_1984.pdf

high-latitude F-region isstudied usingdatafrom the EISCAT Common ProgrammeZero mode ofoperation on 11-12 August 1982. The analysis of the raw autocorrelation functions is kept to the directly derived parameters N, 7 ” T, and velocity, and limits are defined for the errors introduced by assumptions about ion composition and by changes inthe transmitted power and system constant. Simple data-cleaning criteria are employed to eliminate problems due to coherent signals and large background noise levels. The observed variations in plasma densities, temperatures and velocities arc interpreted in terms of supporting data from ISEE- and local riometers and magnetometers. Both field-aligned and field-perpendicular plasma flows at Tromso showed effects of the northward IMF: convection was slow and irregular and field-aligned flow profiles were characteristic of steady-state polar wind outflow with flux of order lOi me2 s-‘. This period followedastronglysouthwardIMFwhich hadtriggeredasubstorm.Thesubstormgaveenhancedconvection, with a swing to equatorward flow and large(5 x 1Oi * m- * s- ‘), steady-state geld-aligned fluxes, leading to the possibility of O+ escape into the magnetosphere. The apparent influence of the IMF over both field-perpendicular and field-aligned flows is explained in terms of the cross-cap otential difference and the location of the aurora1 oval. 1. tNTRODUCTlON