This work presents some results of three years of ionospheric cosmic noise absorption research. The principle of the cosmic-noise method used to measure the changes of ionospheric absorption is quite simple. The apparent intensity of cosmic radio emission is monitored continuously by a stable receiver. Since the galactic radio flux is constant over a long period of time, it can be presumed that any changes in the apparent intensity from one day to another day at the same sidereal time means variations of ionospheric absorption. This work is based on cosmic noise absorption (CNA) data acquired by 30 MHz traditional riometer connected to a five element antenna Yagi-Uda pointed to the zenith direction located at the Brazilian Antarctic Station (BAS- 62,56°S; 58,39°W) and Cachoeira Paulista (22.50°S; 45.00°W), obtained from January-1989 to December-1996. Solar transients events, Traveling Ionospheric Disturbances (TID), seasonal variation of CNA associated with the solar activity, Equatorial Anomaly evolution among others were detected through the analysis of these data. Also, it was developed an ionospheric numerical model which describe the local electron precipitation events from 65km to 120km of altitude by solving the continuity equations for 25 positive ions and 10 negative ions and involving 175 chemical reactions.