The proposed result contains several studies aimed to characterize the variations of ionospheric density and its variability under conditions of magnetic tranquility and different levels of the solar cycle’s activity. It is divided in the main following paragraphs:

1) Procurement of an empiric model of Ionosphere's electronic concentration over Cuba. This model made possible characterizing the daily, seasonal and recurrent variations of this profile. It constitutes a substantive contribution to study the Ionosphere, and among other aspects, it contributes mitigating the affectations that ionospheric absorption causes on transmissions for telecommunication or surveillance. It is also incorporated here the User's Manual and diskette with GUISHA files (Guide User Interface to Spherical Harmonic Analysis), which is an interactive application with the user to analyze and estimate the space behavior of F2 layer's critical frequencies of the Ionosphere on certain regions of the planet.

2) Regional two-dimensional representation of Ionosphere's maximum electronic concentration. It is the first model for this variable in the Region of the Gulf of Mexico and the Caribbean Sea, practically lacking of ionospheric seasons. This method extended to other regions of the planet with very good results.

3) Variability of the electronic concentration of Equatorial and low-latitude Ionospheres. This last paragraph, developed by request of the IRI Task Forced Activity'03, contributed to the improvement of the new versions of IRI (International Reference Ionosphere).

The results previously described, validated in prestigious publications and presented in high-level events in this specialty, answer both scientific interests and practical requirements. It includes references from national and international institutions.