著者

Ryuho Kataoka Stephen D. Winn Emile Touber

出版者

公益社団法人 日本気象学会

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.18, pp.116-121, 2022 (Released:2022-06-11)

参考文献数

8

被引用文献数

3

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Large-amplitude meteotsunamis were observed in many areas in Japan, following the arrival of barometric Lamb waves emitted by an underwater volcanic eruption of Hunga Tonga-Hunga Ha‘apai in January 2022. We modeled the power spectra of the tidal level data obtained from 12 tide stations of the Geospatial Information Authority of Japan, based on a method of transfer function which converts the barometric pressure pulse spectra into the meteotsunami spectra. The obtained transfer functions are similar at 12 stations. The pressure pulse spectra are obtained from the ensemble average of ∼1500 Soratena weather sensors of Weathernews Inc. distributed over Japan. The observed meteotsunami spectra can be characterized by the enhanced seiche eigenmodes at each station excited by the mesoscale pressure pulse within the amplitude error of 50%, which contributes for accumulating the necessary knowledge to understand the potential dangers in various different areas over Japan.

著者

片岡 龍峰 山本 和明 藤原 康徳 塩見 こずえ 國分 亙彦 Ryuho KATAOKA Kazuaki YAMAMOTO Yasunori FUJIWARA Kozue SHIOMI Nobuo KOKUBUN

出版者

総合研究大学院大学文化科学研究科 / 葉山町(神奈川県)

雑誌

総研大文化科学研究 = Sokendai review of cultural and social studies (ISSN:1883096X)

巻号頁・発行日

no.16, pp.17-29, 2020-03

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日本最古の天文現象の記録は、『日本書紀』巻二十二、推古二十八年十二月一日(西暦六二〇年十二月三十日)の條に記される「十二月庚寅朔、天有赤気。長一丈餘。形似雉尾」という一節である。「赤気」は、彗星の類と理解され、日本古典文学や歴史学などの研究では悪い兆候を示すもの、といった理解がなされてきた。その一方、地球物理学においては、オーロラと理解され、オーロラの最も早い事例としてこの『日本書紀』が位置づけられてきた経緯がある。今回の考察では、「赤気」だけではなく、文中の「雉尾」という言葉にも着目し、『日本書紀』諸本での記述を踏まえたうえで、扇形をした赤いオーロラが日本などの中緯度で観察されやすく、真夜中より前に見られ、かつ雉の尾に似た形状をし、「長一丈」に該当する角距離十度相当で見えるという最も構造が際立った形態であるということを、雉の生態など、鳥類学の研究も踏まえて明らかにした。文献学的な考察に加え、雉の生態や尾羽の特徴を理解する鳥類学、彗星に関する古天文学の知識も合わせて新たな考察を加えたことによって、『日本書紀』の編纂に当たった人々の記述に対する責任感や知性、私たち日本人のルーツとなった倭の人々の観察眼や感性を伺い知るうえで一定の視点を与えることに寄与しうるものである。The oldest record of an astronomical phenomenon in Japan was recorded in the Nihon-shoki as follows: "On December 30 in 620, a red sign appeared in heaven. The length was more than 1 jo (10 degrees). The shape was similar to a pheasant tail (Suiko-Tennou, 28)". The appearance of a red sign has been recognized as an expression of a bad omen in literature, while it has been interpreted as the northern lights in geophysics. First we examine the description of the pheasant tail in detail. We then introduce the latest scientific findings that the northern lights show a fan-shaped appearance with a red background when appearing over Japan. After showing that the fan-shape is similar to a pheasant tail, also pointing out the low possibility of comets, we conclude that the oldest record of the red sign is consistent with the appearance of the northern lights over Japan. We hope that this examination contributes to increasing awareness of the sensitivity of Japanese people 1400-years-ago who compared a beautiful behavior of birds with a magnificent and rare natural phenomenon.

著者

Ryuho Kataoka Stephen D. Winn Emile Touber

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.2022-019, (Released:2022-04-26)

被引用文献数

3

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Large-amplitude meteotsunamis were observed in many areas in Japan, following the arrival of barometric Lamb waves emitted by an underwater volcanic eruption of Hunga Tonga-Hunga Ha‘apai in January 2022. We modeled the power spectra of the tidal level data obtained from 12 tide stations of the Geospatial Information Authority of Japan, based on a method of transfer function which converts the barometric pressure pulse spectra into the meteotsunami spectra. The obtained transfer functions are similar at 12 stations. The pressure pulse spectra are obtained from the ensemble average of ∼1500 Soratena weather sensors of Weathernews Inc. distributed over Japan. The observed meteotsunami spectra can be characterized by the enhanced seiche eigenmodes at each station excited by the mesoscale pressure pulse within the amplitude error of 50%, which contributes for accumulating the necessary knowledge to understand the potential dangers in various different areas over Japan.