Detection of Daytime Ionospheric Irregularities at Low Latitudes With a Multistatic HF Radar

We report a new observation of daytime ionospheric irregularities on December 27, 2009, at low latitudes in China using multistatic HF radar. The transmitter, with a horizontal polarization log-periodic antenna pointing westward, is located at Wanning (18.97 degrees N, 110.50 degrees E, dip angle 19 degrees). Three separate receivers are in Sanya (18.20 degrees N, 109.49 degrees E), Qiongzhong (19.04 degrees N, 109.77 degrees E), and Tunchang (19.42 degrees N, 110.13 degrees E). Doppler spectra, frequency power spectra, and wavenumber power spectra from the three receivers were calculated. The main features of these observations are: 1) the irregularities observed at 12:10 (LT) had typical lengths on the scale of tens of meters and the altitude was in the range of 105-175 km, which is located in the E region and bottom of the F region; 2) the power distributions from the three receivers are consistent with the irregularities being field aligned; and 3) features consistent with a cascade of irregular spatial scales were observed. We suggest that the observed irregularity could be due to the intermediate layer modulated by electrodynamic instability.