Quiet-condition variations in the scale height at F2-layer peak at Jicamarca during solar minimum and maximum

摘要

This study is the first attempt to examine the quiet-condition variations inscale height (Hm) near the F2-layer peak in the equatorial ionosphere. Thedata periods of Hm derived from the Jicamarca ionograms are January-December1996 and April 1999–March 2000. The results show that the greatest andsmallest Hm values are generally at 11:00–12:00 LT and 04:00–05:00 LT,respectively. Additionally, the sunrise peak occurs at 06:00 LT only duringsolar minimum. The post-sunset peaks in the equinoctial and summer monthsare more obvious during solar maximum. The Hm difference between solarminimum and maximum are significant from afternoon to midnight. On the otherhand, the Hm values during 07:00–10:00 LT for solar minimum are close to thosefor solar maximum. Furthermore, the correlation of Hm with the criticalfrequency (foF2) of F2-layer is generally low. In contrast, the correlationbetween Hm and the peak height (hmF2) of F2-layer is high. For Hm and thethickness parameter (B0) of F2-layer, the correlation between these twoparameters is almost perfect.