IONOSPHERIC COMPOSITION MEASUREMENT BY EISCAT USING A GLOBAL FIT PROCEDURE

The aim of this paper is to show the gain of the global fit procedure compared to the classical gate-by-gate analysis in the simultaneous de termination of the temperatures and composition profiles in the lower F region. A method for the evaluation of the transition altitude and t he width of the transition region between molecular and atomic ions is described in the case of the EISCAT CP1 experiment; it is validated u sing a simulated experiment. It is shown that alternating-code gates h ave to be processed together with the long-pulse gates. Our new method is applied on six days of actual data. The results obtained during qu iet periods are compared with independent estimations.