Sudden Stratospheric Warming Event Influence on the Equatorial Ionization Anomaly

The present study investigates the ionospherics effects and influences on the equatorial ionization anomaly (EIA) over the Brazilian region caused possibly by a sudden stratospheric warming (SSW) event that occurred in Northern Hemisphere during January – February 2009. We use digisondes installed in Fortaleza (3.8° S; 38° W) and Cachoeira Paulista (22.5° S; 45° W) and total electron content (TEC) from GPS receivers installed in São Luís (2.6° S; 44.2° W) and São José dos Campos (23.2° S; 45.8° W) to obtain the parameters ΔfoF2 (F2 layer critical frequency variation) and ΔVTEC (vertical TEC variation) respectively, which can be used to quantify the intensification or suppression of the EIA.