Large ionospheric TEC depletion induced by the 2016 North Korea rocket

A rocket called Kwangmyongsong-4 was launched from North Korea at 00:30 UT on February 7, 2016. We investigated ionospheric total electron content (TEC) depletions induced by the rocket using the Global Navigation Satellite System (GNSS) stations in South Korea. A sudden depletion in TEC variations appeared ∼6 min after the rocket launch. The drops in slant TEC exceeded 17 TEC unit (TECU) and those in vertical TEC were approximately 7 TECU. It is remarkable that the TEC drop by the 2016 Kwangmyongsong-4 rocket is larger (almost by three times) than that by the 2012 Unha-3 rocket. There are the differences of the background TEC values at the 2012 and the 2016 cases. These results suggest that the difference of the background electron density affects the magnitude of TEC depletion. The horizonal velocity of the rocket was 1.6 km/s, which was estimated from horizontal distances with an initial time of TEC disturbances. However, the 2012 Unha-3 rocket (∼2.5 km/s) moved faster horizontally than the 2016 Kwangmyongsong-4 rocket. Furthermore, when the rocket moved from high latitudes to low latitudes, TEC disturbances reduced gradually, and then, the depletion persisted for a longer time at the west side (the right side of southern direction).