- 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.
- 著者
- Ishii Masao Kosugi Naohiro Sasano Daisuke Saito Shu Midorikawa Takashi Inoue Hisayuki Y.
- 出版者
- American Geophysical Union
- 雑誌
- Journal of Geophysical Research, Oceans (ISSN:01480227)
- 巻号頁・発行日
- vol.116, pp.C06022, 2011-06-28
- 被引用文献数
- 58
Ocean acidification resulting from increases in present and future atmospheric CO2 levels could seriously affect diverse coastal and oceanic ecosystems. In this work, we determine that a significant trend in ocean acidification is superposed on the large seasonal and interannual variabilities of acidity in surface waters off the south coast of Honshu, Japan, based on our repeated observations of partial pressure of CO2 (pCO2), total inorganic carbon (TCO2), and pH. Multiple regression analysis of TCO2 as a function of temperature, salinity, and timing of observations shows that TCO2 increased at a rate of + 1.23 ± 0.40 μmol kg^[-1] yr^[-1] for the period 1994-2008, while no long-term change has been determined for total alkalinity calculated from TCO2 and pCO2 in seawater. These results indicate that pH and the aragonite saturation state (Ωarag) are decreasing at a rate of -0.020 ± 0.007 decade^[-1] and -0.12 ± 0.05 decade^[-1], respectively. If future atmospheric CO2 levels keep increasing as predicted by the Intergovernmental Panel on Climate Change emission scenario A1FI, which postulates intensive fossil fuel use associated with very rapid economic growth, a further reduction of -0.8 to -1.0 in Ωarag is likely in the next 50 years. Such a rapid reduction of Ωarag could have negative impacts on a variety of calcareous organisms.