Efectos de tormentas geomagnéticas sobre la ionosfera de las estaciones El Cerrillo (Toluca, México) y Boulder (Colorado, EUA)

in this work we studied three individual magnetic storm events, with data collected in the ionospheric stations of el cerrillo toluca (mexico) and boulder ( colorado), in which both positive and negative storm effects can be observed. a descriptive analysis of 35 intense magnetic storms (dst <-100 nt), reported for the period of january of 1972 to december of 1982 was also performed. the results show that in average, during a solar cycle, the storms seem not to affect the ionosphere on toluca, since the interval of criticalfrequency deviation, δfof2, is ~10 %. on the contrary, the ionosphere on boulder have a clear effect on the negative phase. if we have in mind the solar activity and the local time, an effect of positive phase on toluca and an effect of negative phase on boulder can be observed.