TI - Time variation of the vertical magnetic cutoff rigidities over the South Atlantic Magnetic Anomaly PY - 2009 AU - Frigo, Everton AU - Pacca, Igor Ivory Gil AU - Hartmann, Gelvam T2 - International Congress of the Brazilian Geophysical Society PP - Rio de Janeiro PB - Sociedade Brasileira de GeofĂ­sica ER -