著者

OZEKI M.

雑誌

Journal of Geophysical Research (ISSN:01480227)

巻号頁・発行日

vol.115, no.9, 2010

被引用文献数

2 61

---

A dense array of Global Positioning System (GPS) receivers is a useful tool to study ionospheric disturbances. Here we report observations by a Japanese GPS array of ionospheric holes, i.e. localized electron depletion. They were made by neutral molecules in exhaust plumes (e.g. water) of ballistic missiles from North Korea, Taepodong-1 and -2, launched on August 31, 1998, and April 5, 2009, respectively. Negative anomaly of electron density emerged ~6 minutes after the launches in the middle of the Japan Sea, and extended eastward along the missile tracks. By comparing the numerical simulation of electron depletion and the observed change in ionospheric total electron content, we suggest that the exhaust plumes from the Taepodong-2 second stage effused up to ~1.5 x 1026 water molecules per second. The ionospheric hole signature was used to constrain the Taepodong-2 trajectory together with other information, e.g. coordinates of the launch pad, time and coordinates of the first stage splashdown, and height and time of the second stage passage over Japan. The Taepodong-2 is considered to have reached the ionospheric F region in ~6 minutes, flown above northeastern Japan ~7 minutes after the launch, and crashed to the Pacific Ocean without attaining the first astronautical velocity. Ionospheric hole in the 1998 Taepodong-1 launch was much less in size, but it is difficult to compare directly the thrusts of the two missiles due to uncertainty of the Taepodong-1 trajectory.