Statistical characteristics of nighttime mid-latitude F-region field-aligned irregularities observed by Daejeon VHF coherent scattering radar in South Korea

Monday, 15 December 2014
Tae-yong Yang1,2, Young-Sil Kwak1,2, Hyosub Kil3, Youngsook Lee1, Woo Kyoung Lee1 and Young-deuk Park1, (1)KASI Korea Astronomy and Space Science Institute, Daejeon, South Korea, (2)University of Science and Technology, Daejeon, South Korea, (3)Johns Hopkins University, Baltimore, MD, United States
 We report statistical characteristics of mid-latitude nighttime F-region field-aligned irregularities (FAIs) based on more than three-year observations by Daejeon VHF coherent backscatter radar. This radar has built at Daejeon (36.18°N, 127.14°E, dip lat. 26.7°N) in 2009 with 40.8 MHz operating frequency for continuous monitoring of the behavior of electron density irregularities in the middle latitude. By using long-term observations from January 2010 to December 2013, we obtained the annual, diurnal and seasonal characteristics of a variety of a percentage occurrence, signal-to-noise ratio, and Doppler velocities from the nighttime F-region irregularities over Korea peninsular. From almost four-year observations, the F-region nighttime irregularities occurred most frequently during post-sunset period. These nighttime irregularities usually appeared with occupying different height levels according to local time. This height variation of F-region FAIs was correlated with hmf2 of ionosonde in Icheon, South Korea. The irregularities were least active near the winter solstice and most active near summer solstice. From the annual occurrence variations, F-region nighttime irregularities seem to have tendency with solar activity.