Efeitos de Explosões Solares na Baixa Ionosfera na Região da Anomalia Geomagnética do Atlântico Sul

Abstract

Two different techniques were used to analyze comparatively the behaviour of the D-Region when solar flares occur. The first one uses an oblique LF/VLF lonossonde at 35 kHz and 45 kHz, located in the South Atlantic Geomagnetic Anomaly (SAGA) region, close to its central point. The second one uses long distance VLF propagation phase measurements at 16 kHz, crossing only part of the SAGA. Several parameters were analyzed, such as ionospheric reflection height, ionospheric ionization and recovery time, duration and the recombination coefficient for each event.

Solar flare ionization times appear to be larger for ionosonde data, compared to long distance propagation data. Recovery times and total durations are shorter for ionosonde data. Similar values of recombination coefficient are found for both techniques. However, the dependence of the recombination coefficient on the flare X-ray intensity is different for the two techniques