| 著者名 | Authors | 所属機関名 | 所属機関名(欧文) | |
| 1 | #杉野/正彦 | Sugino/Masahiko | 名古屋大学太陽地球環境研究所 | Solar-Terrestrial Environment Laboratory |
| 4 | 野澤/悟徳 | Nozawa/Satonori | 名古屋大学太陽地球環境研究所 | Solar-Terrestrial Environment Laboratory |
| 5 | 藤井/良一 | Fujii/Ryoichi | 名古屋大学太陽地球環境研究所 | Solar-Terrestrial Environment Laboratory |
| 6 | 國分/征 | Kokubun/Susumu | 名古屋大学太陽地球環境研究所 | Solar-Terrestrial Environment Laboratory |
講演予稿:
極域において観測される移動性電離層擾乱は、大気重力波により引き起こされる
と考えられている。しかし、近年、それ以外のメカニズムによっても引き起こさ
れることが、モデルまたは観測から証明されるようになった。
北欧のスヴァールバル島に新しく建設された非干渉散乱レーダーにより、またこ
れまでに観測された様相とは違った移動性電離層擾乱が観測された。それは、大
気重力波によってダイレクトに引き起こされるのではなく、磁気圏からの周期性
のある粒子の降り込みに強く関係をもつと思われる。また、その粒子の降り込み
は、惑星空間磁場変動にも依存することが、衛星による観測から示唆された。
abstract:
Traveling ionospheric disturbances (TIDs) appear as wave-like
fluctuations in ionospheric parameters, namely electron density,
electron temperature, ion temperature and ion velocity. They
have been interpreted as the ionospheric signatures of
atmospheric gravity waves (AGWs).
Recently, Kirchengast [1997] presented simulations of TIDs which
are caused by AGWs as well as by other processes. For example,
particle precipitation can also cause wave-like signatures in
the ionosphere, if it occurs in a periodic manner. Rinnert
[1996] reported that the controlling source of such
precipitation variations is in the magnetosphere.
In July 1997, the first Japanese special campaign using EISCAT's
new incoherent scatter radar on Svalbard, ESR (geographic
coordinates, 78'09N, 16.03E), was conducted. During this
periods, wave-like signatures of magnetic field aligned ion
velocity, quasi-periodic enhancements of electron density and
ion temperature were observed over several hours in the daytime.
The dominant periods are about 20 minutes. Except the ion
velocity, other parameters seem to have no significant phase
change with altitude as one would expect it for a process
controlled by AGWs. A clue for the cause of the observed TIDs
comes from data of the GEOTAIL satellite. The IMF Bz was
changing over about the same typical periods as the ionospheric
parameters. The characteristics of our observations are
different from events which have been detected with the EISCAT
UHF radar near Tromso. They seem not to be caused by an AGW
mechanism.
References
Kirchengast,G., JGR, 102, 4597, 1997
Rinnert,K., Ann.Geophys., 14, 707, 1996
Acknowledgement.
We are indebted to the Director and staff of EISCAT for
operating the facility and supplying the data.
EISCAT is an international Association supported
by Finland(SA), France(CNRS), the Federal Republic of
Germany(MPG), Japan(NIPR), Norway(NFR), Sweden(NFR) and
the United Kingdom(PPARC).
キーワード:
移動性電離層擾乱、大気重力波、非干渉散乱レーダー
Keywords:
TIDs,AGWs,EISCAT,precipitation