E-region irregularity observed by the Tanegashima Frequency Agile Radar during SEEK-2 campaign

Abstract

The present paper reports the nighttime field-aligned plasma irregularity (FAI) at 6.1 m in E-region during SEEK-2 (Sporadic E Experiment over Kyushu) campaign during July-August 2002 using Tanegashima (30.75ºN, 131.03ºE, geomagnetic 20.97ºN, dip 43.2ºN) Frequency Agile Radar (FAR) operated at 24.515 MHz. According to the characteristics of radar echo, the echoes are classified into four types: negative quasi-periodic (NQP) echo; positive quasi-periodic (PQP) echo; continuous echo; and undefined echo. A study shows that FAI appear generally at 80-110 km altitudes during 1800-0400 hrs LT, and FAI occur most frequently at 2200 hrs LT. Further, among the four different echo types, the occurrence probability of NQP is greater than other types.