巻号一覧
36 巻 (1990)
- 4 号 p. 219-
- 3 号 p. 143-
- 2 号 p. 73-
- 1 号 p. 1-
36 巻, 4 号
選択された号の論文の6件中1～6を表示しています
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木股 文昭, 臼井 和平, 中村 勝, 宮島 力雄, 奥田 隆, 角野 由夫, 藤井 巌, 村田 一郎, 加藤 照之, 矢吹 哲一朗, 金沢 ...1990 年 36 巻 4 号 p. 219-230
発行日: 1990/12/25
公開日: 2010/09/07
ジャーナル フリーWe repeated GPS measurements on two twelve observation points in the southern region of Chubu and Kanto district in March 1989 and January 1990 to detect the detailed mode of relative motion between the Philippine Sea and the Eurasian plates. The baseline lengths in this GPS network range from 40 km to 1150 km. In the 1989 campaign the satellite constellation over Japan was very poor and four satellites were visible for only several tens of minutes. The satellite visibility has been greatly improved in the campaign of 1990. The short term repeatability of baseline length is generally less than 0.2 ppm in the 1990 campaign, on the other hand it amounts to 2 ppm in the 1989 campaign because of poor satellite configuration. The strain change derived from GPS baseline measurements, except the lines extending from Hachijyo show the contraction of 0.5 ppm in NWN-SES and the extension of 1.5 ppm in ENE-WSW in the period from March 1989 to January 1990. Although the directions of contraction and extension agree with the result obtained from conventional geodetic survey repeated with 100-year interval, the strain rate does not agree. If we discuss GPS measurement with an accuracy of 0.1 ppm, many error sources have to be taken into consideration. Among them, errors in satellite broadcast ephemerides and satellite configuration are dominant sources. We processed the data by utilizing the broadcast orbits elements. The baseline determinations processed by using broadcast orbits which were obtained in different observation sessions in a day shows systematic differences ranging from 0.1 to 0.5 ppm.抄録全体を表示PDF形式でダウンロード (3941K) -
山本 淳, 富沢 一郎, 芳野 赳夫, 今江 理人, 国森 裕生, 三木 千紘, 今村 國康, 川合 栄治, 高橋 冨士信1990 年 36 巻 4 号 p. 231-241
発行日: 1990/12/25
公開日: 2010/09/07
ジャーナル フリーGPSを利用した時刻比較の精度改善のため,時刻比較データそのものを利用して,受信局の位置を推定するソフトウェアを開発し,実際に得られたデータを使用して位置決定を行ってきた.1989年6月に得られた,通信総合研究所,電気通信大学菅平宇宙電波観測所,国立天文台水沢,計量研究所,韓国標準研究所のGPS時刻比較データを使用して,VLBI基準点と結合された通信総合研究所を基準として,各局の位置推定を行い,これらの結果を利用してこの位置推定法の誤差評価を行った.実際的な位置決定精度として,位置決定結果の再現性を考えた場合,この位置決定法の精度として.2～3mが得られた.また,位置決定の精度を,閉合差によって評価した結果,局間距離が1000km程度までではち2～3mの誤差内で位置決定ができることが求められた.さらに,VLBIによる位置決定結果との比較(局間距離約100km)では,推定位置がVLBI基準点とGPS受信アンテナ位置の結合精度程度(約1m)で一致した.GPS時刻比較で,10ナノ秒よりよい時刻比較精度を実現するための,位置決定の許容誤差は,2～3m以下であり,このような簡単な方法で,かつ時刻比較データそのものを利用して,この精度を実現できることが確認された.抄録全体を表示PDF形式でダウンロード (1077K) -
関口 直甫1990 年 36 巻 4 号 p. 243-252
発行日: 1990/12/25
公開日: 2010/09/07
ジャーナル フリーAssuming various types of the excitation functions of the polar wobble, simulated polar orbits are calculated for the respective excitation functions. About these polar orbits, the rotational periods and the mean square radii for respective examples are compared with the values calculated basing on the theory developed in the author's previous paper (SEKIGUCHI, 1990). The results are likely to support the validity of the present theory. In the case of harmonic oscillator, a parallel reasoning is also possible, and the similar simulations are performed.抄録全体を表示PDF形式でダウンロード (981K) -
藤本 博巳, 古田 俊夫, 河内 晋平, 小野 裕一郎, 網敷 俊志, 伊関 伸一, 中久喜 伴益, 高知尾 順治, 秋元 孝敏, 大場 孝 ...1990 年 36 巻 4 号 p. 253-266
発行日: 1990/12/25
公開日: 2010/09/07
ジャーナル フリーGravity measurements were carried out over the Yatsugatake volcanic chain as a part of multi-disciplinary research of the volcanic chain, which lies near the junction of the Median Tectonic Line and the Itoigawa-Shizuoka Tectonic Line, central Japan. Maps of Bouguer anomalies were compiled from the observed gravity data together with other available data. Except for the gravity anomalies corresponding to the Akaishi Mountain, local gravity anomalies around the Yatsugatake volcanic chain are explained by shallow density structures estimated from geological maps. The Yatsugatake volcanic chain is estimated to be on the western border of the basement high of the Kanto Mountain. A negative gravity anomaly is observed over the western flank of the volcanic chain and close to the Itoigawa-Shizuoka tectonic line. The negative gravity anomaly is explained by a low density layer caused by depression in the basement under the western flank of the volcanic chain. Locally positive gravity anomalies found over the oldest rock in the central part of the volcanic chain indicate a small scale high-density structure.抄録全体を表示PDF形式でダウンロード (2999K) -
小野寺 栄喜1990 年 36 巻 4 号 p. 267-276
発行日: 1990/12/25
公開日: 2010/09/07
ジャーナル フリーThe Antarctic Circumpolar Current (ACC) is the only tonal ocean flow around the axis of Earth's rotation. It can directly exchange the angular momentum with Earth's rotational motion. The Trans-Polar Index (TPI), variations of the pressure at the sea surface and the air temperature in the Antarctic show correlations with variations of the length of day (lod). Excitations of the Earth's rotational speed are estimated by using variations of the tonal current of the ACC, which are derived from geostrophic balance approximation of the pressure difference at the surface along the meridian. The pressure difference along the meridian is obtained by two methods; one is from the TPI and another is derived from atmospheric temperature at the surface in the Antarctic and the surface pressure at Ushuaia, in front of the Drake Passage. From the estimated excitation of the Earth's rotational speed, the ACC has proved to contribute to the exchange of the angular momentum with the solid part of the Earth. The ACC has also proved to be coupled with the increasing and/or decreasing of the El Nino.抄録全体を表示PDF形式でダウンロード (903K) -
中根 勝見1990 年 36 巻 4 号 p. 277-278
発行日: 1990/12/25
公開日: 2011/03/01
ジャーナル フリーIn geodetic network, coordinates (unknown values) are nonestimable, while observation values are estimable. Observation values are, however, not estimable under the condition that more than two stations are held fixed in the network.抄録全体を表示PDF形式でダウンロード (151K)
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