Comparisons between EISCAT observations and model calculations of the high-latitude ionosphere

• Main Authors: S. Quegan, R. S. Gill, M. Lockwood
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1988
• Subjects: Spiro; EISCAT
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.694.6109; http://www.eiscat.rl.ac.uk/Members/mike/publications/pdfs/1988/45_Queganetal_1988.pdf

Abstract-Calculations using a numerical model of the convection dominated high latitude ionosphere are compared with observations made by EISCAT as part of the UK-POLAR Special Programme. The data used were for 24-25 October 1984, which was characterized by an unusually steady IMF, with Bz < 0 and Ey> 0: in the calculations it was assumed that a steady IMF implies steady convection conditions. Using the electric field models of HEPPNEK and MAYNARD (1983) appropriate to Ey> 0 and precipitation data taken from SPIRO et al. (1982), we calculated the velocities and electron densities appropriate to the EISCAT observations. Many of the general features of the velocity data were reproduced by the model. In particular, the phasing of the change from eastward to westward flow in the vicinity of the Harang discontinuity, flows near the dayside throat and a region of slow flow at higher latitudes near dusk were well reproduced. In the afternoon sector modelled velocity values were significantly less than those observed. Electron density calculations showed good agreement with EISCAT observations near the F-peak, but compared poorly with observations near 211 km. In both cases, the greatest disagreement occurred in the early part of the observations, where the convection pattern was poorly known and showed some evidence of long term temporal change. Possible causes for the disagreement between observations and calculations are discussed and shown to raise interesting and, as yet, unresolved questions concerning the interpretation