Equatorial sporadic E-layer abnormal density enhancement during the recovery phase of the December 2006 magnetic storm: A case study

Abstract

Sporadic layers appear in the equatorial region (E ^sub sq^) between 90 and 130 km mainly due to irregularities in the electrojet equatorial (EEJ) current. In the present work, we have analyzed the behavior of the frequency parameters associated with these sporadic layers, covering the days before, during, and subsequent to, the intense magnetic storm that occurred on December 14, 2006. The parameters used in our analyses are the top frequency (f ^sub t^ E ^sub s^) and blanketing frequency (f ^sub b^ E ^sub s^) of the E ^sub s^ layer as measured over São Luís, Brazil (2.33°S, 44.2°W, dip: -4.5°) by digital ionosonde. A tentative association between these parameters and X-ray data measured by sensors on board the GOES satellite was carried out. Also, we investigated the effects on the dynamics of the equatorial electrojet using magnetometer data related to the presence of these E ^sub s^ layers. Our analyses show that there are notable changes in the f ^sub b^ E ^sub s^, which are characterized by the occurrence of peaks that exceed the ambient background values.