Seeding Effect on the Spread F Generation in the South American Region

The seed perturbation is considered as an important factor in the generation of plasma irregularity during the period characterized by a weak ambient ionospheric condition. Thus, the seed perturbation induced by the upward propagating gravity wave (GW) activity could significantly influence the longitudinal distribution of the ESF occurrence across a region. The locally generated ESF events were manually obtained from ionogram data at the Jicamarca station (JIC: 75.760W,8.170S) and the Sao Luis station (SL: 44.20W,2.60S) during the equinoctial months of 2009 and 2010. This was compared with the frequency of GW activity at both longitudes, using the interpolated outgoing longwave radiation (OLR) map. The enhanced plasma irregularity during both equinoctial months at the Jicamarca station was attributed to the presence of the strong GW activity near the magnetic equator of this longitude.