The climatology of ionospheric plasma bubbles and irregularities over Brazil

In this paper, we examine ionospheric plasma depletions (or bubbles) and irregularities observed by photometers and a ground-based receiver of the global positioning system (GPS) both located in Brazil, South America. A simultaneous observation reveals that when the ionospheric plasma becomes depleted, the GPS total electron content decreases and the associated phase fluctuations grow. Statistical results show that the plasma bubbles and the significant GPS phase fluctuations generally occur during October-March. The solar activity variation is not obvious in either observation except during the equinoctial months. The GPS phase fluctuations suggest that the most pronounced ionospheric irregularities appear between 20:00 and 01:00 LT, which generally agree with previous ionospheric bubble observations.

Relation of Magnetic Fields with Solar Activity Indexes in a Descending Phase of Solar Cycle

We examine the solar activity indexes (relative intensity of sunspots and faculae) of an active region #83137 during 1983 June 21–26. The results are compared with daily variation of magnetic fields of the region to find a characteristic of solar activity variation in the descending phase of solar cycle.