ALBERT

Description: [1]  We analyze data recorded from October 2010 to September 2011, during the ascending phase of the 24 th solar cycle, from an AIS-INGV (Advanced Ionospheric Sounder - Istituto Nazionale di Geofisica e Vulcanologia) ionosonde and a GISTM (GPS Ionospheric Scintillation and TEC Monitor) scintillation receiver, co-located at low-latitude in the Southern American longitudinal sector (Tucumán, 26.9°S, 294.6°E, mag. Lat. 15.5°S, Argentina). The site offers the opportunity to perform spread-F and GPS scintillation statistics of occurrence under the southern crest of the equatorial ionospheric anomaly. Spread-F signatures, classified into four types (strong range spread-F (SSF), range spread-F (RSF), frequency spread-F (FSF) and mixed spread-F (MSF)), the phase and amplitude scintillation index ( σ Φ and S 4 , respectively), the total electron content ( TEC ) and the rate of TEC ( ROT ) parameter, marker of the TEC gradients, that can cause scintillations, are considered. The seasonal behavior results as follows: the occurrence of all four types of spread-F is higher in summer and lower in winter, while the occurrence of scintillations peaks at equinoxes in the post-sunset sector and shows a minimum in winter. The correspondence between SSF and scintillations seems to be systematic, and a possible correlation between S 4 and FSF peaks is envisaged at the terminator. The investigation focused also on two particular periods, from 12 to 16 March 2011, and from 23 to 29 September 2011, both characterized by the simultaneous presence of SSF signatures and scintillation phenomena allowing to discuss the role of Travelling Ionospheric Disturbances as a strong candidate causing ionospheric irregularities.