The SWILM approach for regional long-term modelling of middle/high latitude ionosphere

The Space - Weighted Ionospheric Local Model, SWILM, is an alternative appr oach developed for the regional long-term mapping and modelling of the plas ma frequency of the F2 layer, foF2, and the M(3000)F2 propagation factor. T his model is based on the past monthly medians data from several vertical s ounding stations in the region of interest and on the R-12 index as indicat or of the solar activity. In order to allow users to switch to a planetary scale, a good merge with the global ITU-R (Radiocommunication Sector of the International Telecommunication Union) model is also provided by SWILM wit h acceptable gradients at the borders of the region. In this paper the basic formulation of the model will be given and the resu lts will be shown as obtained by comparing SWILM and ITU-R performances for mapping and modelling the foF2 and the M(3000)F2 over a geographic area ra nged between 35 degrees-70 degrees N and 10 degrees W-60 degrees E. (C) 200 0 Elsevier Science Ltd. All rights reserved.