On new detailed ionogram signatures of Equatorial Plasma Bubbles from non-equatorial station during low solar activity
A first - time direct comparison between climatology of spread F (SF) observed at Phu Thuy and DMSP, C/NOFS satellite measurements during years of low solar activity conditions 2007 - 2010, together with ionosonde observations under the same solar conditions 1953 - 1955 in Baguio, is made to show good relationship of SF at off-equator and equatorial plasma bubbles over the dip equator. The results showed peak of irregularity activities around June solstice, which again confirmed the breakthrough findings by satellites as one typical characteristics of ionospheric structures during low solar activity. We also found that we cannot use typical types of SF for equatorial stations as the ones observed at non-equatorial stations. Instead, we suggested a new method to classify SF types in the relation to ionospheric structures at the off-equator stations of interest. Consequently, we can explain, in the simplest cases, for the first time, complex range type SF observed at off-equatorial stations and name a new type as indicator of EPB occurrence.
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