occurrence of eej irregularities under disturbed - DGE

OCCURRENCE OF EEJ IRREGULARITIES UNDER DISTURBED
MAGNETIC ACTIVITY VS QUIET CONDITIONS
Lais Maria Guizelli - INPE ([email protected])
Clezio Marcos De Nardin - INPE
Pedro Daniel Carvalho Santos de Almeida - INPE
Henrique Carlotto Aveiro - Universidade de Cornell - NY - EUA
Laysa Cristina Araújo Resende - INPE
E-mail for contact: [email protected]
Abstract
The ionosphere is a region ionized of the Earth’s atmosphere situated between 60 and 2000 km
of height and is classified in layers (namely, D-, E- and F-region). In this study, the focus is the
Equatorial Electrojet (EEJ), an intense electric current that flows at the E-region heights
centered on the magnetic equator. This phenomenon may generate two types of plasma
irregularities: Type 1 (modified two-stream instability) and Type 2 (gradient-drift instability).
The spectrum related with Type 1 irregularities shows a thin spectral width, with its center of
distribution located close to the ion-acoustic speed (~ 360 m/s). Type 2 spectra has larger
spectral width than the previous type and smaller Doppler velocities than the ion-acoustic
speed. We show a statistical occurrence of EEJ irregularities in function of height and time
under disturbed magnetic activity and quiet conditions based on data taken from the westward
oblique beam of the 50 MHz coherent backscatter radar installed in São Luís – MA, Brazil (2°31´
S, 44°16´ W).