A set of regional maps of peak electron density in the northern polar cap was deduced from aeronomical computations for southward IMF executed at Utah State University (USU) /1/. Each of the 12 maps holds for invariant latitudes greater than 50° N, covering 24h both in magnetic local time and in UT. The maps for two parameters are analyzed in terms of Empirical Orthogonal Functions (EOF). The dependence on other parameters is described by continuous functions. In the northern polar cap, these maps might be used as a partially substituting supplement of the world wide maps recommended by the CCIR/2/.