A NUMERICAL STUDY OF IONOSPHERIC PROFILES FOR MIDLATITUDES

This paper presents a numerical model and results for the mid-latitude ionospheric profile below the peak of the F-2-layer. The basis of the model is the solving of equations for four ionic species O+, NO+, O-2 (+) and N-2(+), as well as the meta-stable O+ (D-2) and O+ (P-2). Diff usion and wind-induced drifts and 21 photo-chemical reactions are also taken into account. Neutral atmospheric density and temperature are d erived from the MSIS86 model and solar extreme ultra-violate irradianc e from the EUV91 model. In an effort to obtain a more realistic ionosp heric profile, the key point at foF(2) and hmF(2) is fitted from the s imulation to observations. The model also utilizes the vertical drifts derived from ionosonde data with the help of the Servo model. It is s hown that the accurately under the derived vertical drifts from the Se rvo theory than the HWM90 model. Results from the simulation are given for Wuchang (30.5 degrees N, 114.4 degrees E) and Wakkanai (45.6 degr ees N, 141.7 degrees E), showing the profile changes with season and s olar activity, and the E-F valley structure (the depth and the width). This simulation also reveals the importance of meta-stable ions and d ynamical transport processes on the formation of the F-1-ledge and F-1 -F-2 valley.