著者

岡田 博有 鈴木 茂之

出版者

岡山大学理学部地球科学教室

雑誌

Okayama University Earth Science Report (ISSN:13407414)

巻号頁・発行日

vol.16, no.1, pp.1-7, 2009-12-25

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The first Japanese word "chishitsu-gaku" for the "geology" was proposed by Genpo Mitsukuri, a scientific contributor in the Tokugawa regime in the 19th century, who was born in 1799 in Tsuyama in Western Honshu, Japan and had worked for scientific activities of the Tokugawa government from 1839 to 1863. His major works for the first making of the "chishitsu-gaku" for the "geology" have been presented in this paper, also showing his contribution to Japanese sciences.

著者

狩野 正裕 山川 純次

出版者

岡山大学理学部地球科学教室

雑誌

Okayama University Earth Science Report (ISSN:13407414)

巻号頁・発行日

vol.19, no.1, pp.13-17, 2012-12-26

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Sibirskite (CaHBO ) and parasibirskite ₃ are in the relation of polymorphism, these are regarded as the alterationproducts of takedaite (Ca₃B₂O₆), occurs at Fuka mine, Okayama Prefecture. The synthesis of parasibirskite wasreported by the Schäfer (1968a, b) etc. and the synthesis of sibirskite was reported by the Sun et al. (2011).To determine the formation condition of sibirskite and parasibirskite in the natural, they were synthesized fromthe natural takedaite (Ca₃B₂O₆). As a result, both of sibirskite and parasibirskite were formed by the durationtime of 7 days with 1000 kg/cm2 and 300 oC, on the other hand, only sibirskite was formed by the duration time of14 days with the same condition.In addition, the mixtures of sibirskite and parasibirskite were examined under the various temperatures andpressures of hydrothermal conditions. As a result, the upper limit of the stable temperature and pressureconditions of sibirskite was estimated between 350 oC and 400 oC at 1500 kg/cm2, and between 400 oC and 450 oCat 500 kg/cm2 . In the higher temperature than the condition, sibirskite were changed into shimazakiite (Ca₂B₂O₅).

著者

合田 泰弘 加藤 内藏進 塚本 修

出版者

岡山大学理学部地球科学教室

雑誌

Okayama University Earth Science Report (ISSN:13407414)

巻号頁・発行日

vol.19, no.1, pp.39-50, 2012-12-26

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A case study on persistent appearance of the ensemble of precipitation bands in the warm sector of the Baiu front inKyushu District, the western part of Japan around 19 June 2001 was performed based on the operational observationaldata. Around 00UTC (09JST) 19 June when the Baiu front on the surface weather map was still located about a few100kms to the north of Kyushu, the number and the total area of the meso-β or γ-scale line-shaped precipitationbands increased around Kyushu rapidly. These precipitation bands had been sustained there and gradually gatheredeach other to change into the Baiu frontal precipitation zone extending from the northern Kyushu to Seto-Naikai (SetoInland Sea) around 09UTC (18JST) 19 June (the intense rainfall zone was still located in the warm sector of the Baiufront).Until ~09UTC (18JST) 19 June, the moist air flow with the latently unstable stratification had been sustainedaround Kyushu corresponding to the low-level southerly wind toward the surface Baiu front to the north of Kyushu.This large-scale situation would contribute greatly to the maintenance of the ensemble of the line-shaped precipitationbands in the warm sector of the Baiu front.

著者

松本 健吾 加藤 内藏進 大谷 和男

出版者

岡山大学理学部地球科学教室

雑誌

Okayama University Earth Science Report (ISSN:13407414)

巻号頁・発行日

vol.20, no.1, pp.25-34, 2013-12-27

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Rainfall characteristics and large-scale atmospheric fields on the "heavy rainfall days" (with more than 50mm/day) in the mature stage of the Baiu season (16 June ~ 15 July) at Tokyo in the eastern part of the JapanIslands were examined, based on the daily and the hourly precipitation data from 1971 to 2010.Appearance frequency of the "heavy rainfall days" at Tokyo attained only about 1/3 of that at Nagasaki inthe western Japan. Furthermore, it is noted that about half of the "heavy rainfall days" at Tokyo were relatedto the typhoon. In detail, about half of the typhoon cases were associated with the direct approach of atyphoon (referred to as Pattern A, hereafter), the other half corresponded to the situation when the Baiu frontalso stagnated around Kanto District with a typhoon to the southwest of Kanto (Pattern B).Although the contribution of the intense rainfall with more than 10 mm/h to the total precipitation waslarge in Pattern A, that with less than 10 mm/h was dominant in Patterns B and C (Pattern C: meso-α-scalecyclone on the Baiu front approaching to the Kanto District). It is noted that about half of the "heavy rainfalldays" corresponded to these pattern. In other words, unlike the localized torrential rain in western Japan, the"heavy rainfall days" due to the duration of "not-so-intense-rain" appeared rather frequently in the easternpart of Japan even in the Baiu season.In both Patterns B and C, relatively strong low-level southerly wind associated with the disturbance (atyphoon or a meso-α-scale cyclone) invades into the baroclinic zone in the basic field sustained as thesowthwestern edge of the cool Okhotsk air mass. It is interesting that the "heavy rainfall days" there due tothe contribution of the persistent "not-so-intense-rain" occur just in such situation.