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Using magnetic observatory data to investigate the longitudinal and seasonal variability of the counter electrojet |
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Soares, G. B. (1), Yamazaki, Y. (2), Matzka, J. (2) and Pinheiro, K. (1) |
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(1) Geophysics Department, Observatório Nacional, 20921-400 Rio de Janeiro, Brazil. (2) GFZ German research Centre for Geosciences, 14473 Potsdam, Germany. |
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Data from magnetic observatories placed near the magnetic equator can be used to study the equatorial electrojet (EEJ) and its reversal, the so-called counter electrojet (CEJ). The EEJ is an ionospheric current that flows eastwards at E-region heights within a narrow band of about 4° from the magnetic equator. It causes an enhancement of the normal daily Sq variations in the geomagnetic horizontal component H. CEJ events result from the reversal of the normal EEJ. The westward current during CEJ events can last for a few hours and causes a depression in the H values. One method to isolate the EEJ/CEJ signal from other external and internal sources of the geomagnetic field is by taking the difference of H measured at an equatorial station and at a low-latitude station with a similar longitude, but outside the influence of the EEJ. In this work we aim to provide the seasonal variability of CEJ events by using geomagnetic data from the Peruvian sector (Huancayo observatory and Piura station), the Brazilian sector (Tatuoca and Kourou observatories), the African sector (Samogossoni station and Tamanrasset observatory), the Indian sector (Tirunelveli and Alibag observatories) and the Asian sector (Davao and Muntilupa stations). We investigate if the obtained CEJ rates are in agreement with the longitudinal variation of the ionospheric electric field, which is caused by atmospheric waves of tropospheric origin. A better understanding of the mechanisms that control the longitudinal difference of CEJ occurrences is important for further studies of the whole EEJ/CEJ system. |
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Applications |
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oral |
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