Statistical Investigation of the Saturation Effect of Sunspot on the Ionospheric foF2

摘要

This study explores the relationship between the sunspot number (SSN) and the ionospheric foF2. It is of interest to locate the SSN value at which the foF2 values are saturated. A regression model is built based on the data of the strictly rise period of the 21st solar cycle recorded by eight ionosonde stations scattering roughly between 40 °N and 40 °S geomagnetic latitude. Results show that clear saturation features appear around the equatorial anomaly crest region.