Spread F, GPS phase fluctuations, and plasma bubbles near thecrest of equatorial ionization anomaly during solar maximum

摘要

This work is the first attempt to concurrently study the occurrence probabilities ofspread F, GPS phase fluctuations, and plasma bubbles near the crest of equatorialionization anomaly (EIA). The data were observed by an ionosonde, a GPS receiver, andROCSAT-1 during 2000, the solar maximum year. Results show that the occurrences ofthe range spread F (RSF) differ from those of the frequency spread F (FSF). For theseasonal variation, the RSF occurrence has the maximum values in March and September,while the FSF occurrence peaks at June. For the nighttime variation, RSF and FSF peak at2300 and 0300 LT, respectively. Regarding the GPS phase fluctuations, an index Fp isapplied to characterize the irregularity strength. The similarity between the 50 < Fp < 200and RSF occurrences demonstrates that the characteristics of F region irregularitiesforming 50 < Fp < 200 are mainly related to RSF. The occurrence of 200 < Fp is almostabsent. The rare event is also found in the observation of plasma bubbles by ROCSAT-1.Furthermore, the seasonal variations in GPS phase fluctuations at the EIA crest and the dipequator have similar trends. This indicates that the F region irregularities of RSF and 50