| 著者名 | Authors | 所属機関名 | 所属機関名(欧文) | |
| 1 | #亀井/豊永 | Kamei/Toyohisa | 京都大学理学研究科地磁気世界資料解析センター | WDC-C2 for Geomag., Graduate School of Science, Kyoto University |
| 2 | 荒木/徹 | Araki/Tohru | 京都大学理学研究科地球惑星科学専攻 | Department of Geophysics, Graduate School of Science, Kyoto University |
| 3 | 杉浦/正久 | Sugiura/Masahisa | 東海大総合科学技術研究所 | Research Institute of Science and Technology, Tokai University |
講演予稿:
IAGAの公式地磁気指数であるAE指数は10-13ケ所のオーロラ帯の
地磁気観測所から導出される、年により観測所の組み合わせは
変動しているが、1978に我々が導出を受け持ってから12ケ所の
観測所を標準にしている。観測所の均一分布を考えると殆ど取
り替え、追加が出来ない。近年ロシアの経済情勢の悪化でその
1つケープウエレンが閉鎖された。この取り替えを検討している
が難しい。この影響とその他の観測所について各々の特性を
述べる。また、同時に何個所もの観測所が欠測することの
影響についても述べる。
abstract:
IAGA starndard AE index (Auroral Electrojet index, including
AU, AL and AL indices) has been derived from 10-13 stations
depending on the availability of data and with due regards
the uniformity of the station distribution along the auroral
zone. The combination of stations used for the derivation of
the AE index has varied from time to time mainly because of
the availability of data. Since 1966, when the WDC-A for STP
took this heavy work of the derivation of AE index with 2.5
minute time resolution, the set of (11) stations was nearly
fixed. These were, Abisko (sometimes backed by Sodankyla),
Dikson, Cape Chelyuskin, Tixie, Cape Wellen, Barrow,
College, Fort Churchill, Great Whale River, and Narsarsuaq.
In 1975, the time resolution was changed to one minute, and
Yellowknife was added to the AE stations. Derivation with
one minute time resolution made the task too heavy. And
the derivation of the 1976 and 1977 AE index still remains
undone. We have been deriving the AE index since 1978; it
has been impossible to make any replacement or addition to
the stations execpt in the European area, but any
replacement or addition of station would just distort the
uniform station distribution. We use the same stations as
NOAA did, we call these 12 stations the standard AE
stations.
These 12 stations were selected to have an uniform coverage
in geomagnetic longitude or local time, and also to have an
even distribution in latitude. In the eastern Siberia, we
had no high latitude station because of the Arctic Sea, we
use low latitude station at Cape Wellen. Barrow and Cape
Wellen are an example of a combination of high latitude
and low latitude stations near the same magnetic local
time, this combination tends to change the disadvantage of
the low latitude of Cape Wellen to an advantage.
However, we now have difficult operations of the stations
in Russia for economical reasons. Cape Wellen is too far
away from the main part of Russia; after the power supply
to the station failed in 1996, the station stopped its
operation and there is no possibility to reopen the
station.
The loss of Cape Wellen is not fatal to the current AE
derivation as its latitude is low and the chance of
contribution of Cape Wellen to the AE index is not so
great as other stations. However, we have a long
uncovered longitudinal gap between Tixie and Barrow.
Therefore we are trying to set up a replacement station
in a high latutude location (candidate is Pyebek)
between Tixie and Cape Wellen, though it will take years.
In the previous stuies we showed how the QL AE(8) index is
affected by missing coverage of 4 stations. This study
shows the characteristics of each standard AE station,
and we discuss effects of combination of simaltaneously
missed data, as well as those caused by the loss of Cape
Wellen.
キーワード:
地上観測, 地磁気, 指数, AE指数, オーロラ, 電流
Keywords:
ground observation, geomagnetism, index, ae index, aurora, electrojet