Ionospheric Signatures of North Korean Nuclear Test on 12 February 2013

Previous studies on interactions between the atmospheric waves and ionospheric perturbations concluded that the acoustic-gravity waves triggered by solid earth events such as earthquakes, tsunamis and underground nuclear tests may be used in detecting the ionospheric perturbations. Ionospheric perturbations have been observed using sounding radars and GPS remote sensing techniques since 1970s. As primary examples, ionospheric disturbances associated with 2006 and 2009 North Korean underground nuclear tests were observed using GPS measurements.

In this work, we processed GNSS stations in South Korea and Japan and analyzed traveling ionospheric disturbances that were coincident with the 2013 North Korean underground test. North Korea conducted the third underground nuclear test at 2:57 UTC on February 12, 2013. The magnitude of earthquake generated by this event was registered to be an Mw 5.1 event. After analyzing GPS measurements from nearby stations, strong ionospheric perturbations were observed 15-30 minutes after the reported event, and the disturbances were shown to have primarily two different wave trains. The maximum VTEC perturbations turned out to be between 0.4 to 0.7 TECU. Five stations located in the northwest-to-southeast direction were also scrutinized for the propagation direction and amplitude variation related to ionospheric wave structures. The results clearly showed that the maximum amplitude of the waves may be higher as the stations are closer to the epicenter indicating that the waveforms may propagate away from the epicenter. In this research, we will analyze the characteristics of the detected ionospheric perturbations associated with the underground nuclear test. These findings are expected to verify our modeling results. We hope to get a better understanding of the influence of man-made hazards on the temporal and spatial variability of the global ionosphere.