5:15 PM - 6:30 PM
[PEM18-P12] Frequency and source height of MF/HF auroral radio emissions estimated from the results of EXOS-D/PWS sounder experiments
Keywords:auroral roar, Terrestrial Hectometric Radiation , AKEBONO satellite
In this study, we analyze data obtained from topside sounder experiments by PWS on board the AKEBONO satellite from March 19 to April 18, 2015. We analyze observed ionograms to obtain the height profiles of plasma density. Compared to empirical models such as the International Reference Ionosphere (IRI) model, the sounder experiments can provide more accurate plasma density profiles. The derived density profiles are converted to fUHR profiles in order to estimate the possible frequency and source height of THR. We focus on data obtained in the region of latitude 50-80°N and longitude 50°W-50°E, while the simultaneous ground-based observation has been carried out at Svalbard (latitude 78.15°N, longitude 16.04°E) and Iceland (latitude 64.67°N, longitude 21.03°W). We have obtained 50 density profiles in the selected area and estimated that the expected frequency and the source height of THR corresponding to 2fce are 440-1090km and 1.9-2.5MHz, respectively. We have also found that the matching condition fUHR=3fce was satisfied in 2 cases out of 50 analyzed profiles, which suggests the possibility of the generation of THR corresponding to 3fce. From that 2 cases, we have estimated that the expected frequency and the source height of THR corresponding to 3fce are 330-450km and 3.8-3.9MHz, respectively. In addition, we analyze radio emissions observed by PWS in the selected area during the analyzed period. We have identified 1 event which is considered to be THR corresponding to 2fce, and have found that the emission frequency is within the frequency range estimated by the present study.