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

Abstract. This study is the first attempt to examine the quiet-condition variations in scale height (Hm) near the F2-layer peak in the equatorial ionosphere. The data periods of Hm derived from the Jicamarca ionograms are January-December 1996 and April 1999–March 2000. The results show that the greatest and smallest 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 during solar minimum. The post-sunset peaks in the equinoctial and summer months are more obvious during solar maximum. The Hm difference between solar minimum and maximum are significant from afternoon to midnight. On the other hand, the Hm values during 07:00–10:00 LT for solar minimum are close to those for solar maximum. Furthermore, the correlation of Hm with the critical frequency (foF2) of F2-layer is generally low. In contrast, the correlation between Hm and the peak height (hmF2) of F2-layer is high. For Hm and the thickness parameter (B0) of F2-layer, the correlation between these two parameters is almost perfect.