著者

柳本 俊亮

出版者

公益社団法人 日本気象学会

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.10, no.7, pp.440-442, 1932

著者

山内 安太

出版者

公益社団法人 日本気象学会

雑誌

氣象集誌. 第1輯 (ISSN:00261165)

巻号頁・発行日

vol.34, no.6, pp.324-334, 1915

著者

周 徳 今 久 孫野 長治

出版者

公益社団法人 日本気象学会

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.51, no.1, pp.43-53, 1973

被引用文献数

10

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1970,71年の夏季,札幌において晴天積雲の移動速度をステレオ写真方式で観測した.また雲の周辺の気象条件として札幌管区気象台のレーウインゾンデの資料をつかって解析して次の結果を得た.<br>1.雲底が地上高700m以上の高い晴天積雲では,その移動方向は,その雲の高度(雲底)の風向とよく一致するが,700m以下では地形の影響が大きい.<br>2.晴天積雲の移動速度は一般に雲底高の風速よりおそいが,そのなかで次の傾向が認められた.低い雲ほど,また大きい雲ほどおそい傾向がある.また風の垂直シャー(上方が速い)が大きいほど雲速に比べておそくなる.<br>これらの傾向は,雲内で小さい運動量が下方から輸送されるということで理解される.

著者

木村 富士男

出版者

社団法人 日本気象学会

雑誌

Journal of the Meteorological Society of Japan. Ser. II (ISSN:00261165)

巻号頁・発行日

vol.64, no.6, pp.857-870, 1986

被引用文献数

4

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風の弱く良く晴れた夜に関東平野に低気圧性のうずがしばしば現われることはHarada (1981a) により報告されている。静力学平衡を仮定した Boussinesg 方程式から成る局地風モデルにより, このうずを再現し, Haradaにより指摘されている性質とよく一致することを示す。次に地形を単純化し, クレータのあるガウス型の山を仮定した数値実験により, うずの形成メカニズムを調べる。この結果,次のことが明らかとなった。(1)まず日中に山の上に発達する熱的低気圧に正のうず度が蓄積する。この熱的低気圧は後のうずの生成に重要な役割を持っている。(2)夜になると, 山の斜面に下降流が発達する。山の中央部は発散場になり, うず度は低下する。この結果, 山麓でうず度が最大となる。(3)もし, 山麓にクレータなどがあると, さらにうず度の集中がおこり, 1個の独立したうずが形成される。夜に,クレータなど小規模の地形によりうず度の集中がおこるメカニズムは完全には明確にできたとは言えないが,うず度方程式の各項を見積ると, クレータ状地形の周囲から吹き降す山風の収束によるうず度の増強が最も効いている。山麓付近での高うず度帯の力学不安定については, それだけではうず度の集中をおこさせることはできない。最後に, 北海道においてシミュレーションを実施し, 同様なうずが, 北海道周辺の海上に3個できることを示す。そのうちの一つ, 十勝沖にできるうずは, その陸上側の半分がアメダスによる観測データより, しばしば見い出せる。

著者

Murty L.Krishna

出版者

公益社団法人 日本気象学会

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.54, no.6, pp.370-381, 1976

被引用文献数

14

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AMTEX 75(1975年2月14日~28日)期間の熱&bull;収支解析を行った。解析は,全期間&bull;undisturbed period&bull;disturbed periodの3つの異ったケースについて行われた。<br>全期間の平均状態としては,80mb近傍に逆転層があり,かつその附近で下降流が極大値をとる。 apparent moisture sourceはこの高度附近で極大値を示すが, apparent heat sourceは極小値を示した。<br>disturbed period(AMTEX地域の北に低気圧があり,温い南風の状況)では,逆転層はない。750mb近傍に著しいapparent moisture sinkがあり,そこでは,上昇流の極大とapparent heat sourceの極大がみられる。<br>undisturbed periodは,冷い北風に特徴づけられ,全期間の平均状態に類似しており,逆転面下面附近(~800mb)にapparent moisture sourceがある。<br>海面からの熱エネルギーの補給量は,平均,870ly day-1であり,これはbulk aerodynamic法による推定値と一致している。補給量は寒気吹出時には,1200ly day-1におよぶが, disturbed periodでは140ly day-1にすぎない。

著者

安成 哲三 関 祐治

出版者

公益社団法人 日本気象学会

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.70, no.1, pp.177-189, 1992

被引用文献数

104

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ENSOの時間スケールの地球気候システムの年々変動に果たすアジアモンスーンの役割を、アジアの夏のモンスーン、熱帯太平洋の大気℃海洋結合系及び中緯度の偏西風レジームの間の統計的、力学的な関係を調べることにより、考察した。<br>アジアモンスーンは、熱帯太平洋域での大気・海洋結合系と密接にリンクしており、モンスーン/大気・海洋結合系(略して、MAOSと仮称)とも呼べる一つのシステムをなしていることが明らかとなっている(Yasunari,1990a)。このMAOSは、準2年周期の振動特性を持っており、ある偏差状態は、アジアの夏のモンスーン頃から始まり、約1年持続するという季節性を示す(Yasunari,1991)。<br>このMAOSの偏差状態は、亜熱帯高気圧の強弱やロスビー波の伝播という機構を通して、北太平洋の亜熱帯・中緯度の夏から秋にかけての大気循環に、大きな影響を与えていることがわかった。即ち、モンスーンの弱い(強い)年には、(逆)PNAパターンが卓越する。そして、引き続く冬の半球スケールの偏西風循環は、この秋の大気循環の偏差が初期条件となったような波数1または2のパターンが卓越する。即ち、PNAパターンにより、北米東岸あるいは極東のトラフが発達し、ユーラシア大陸上はより帯状流的な流れのパターンとなる。反対に、逆PNAパターンでは、北太平洋から北米域がより帯状流的となる一方、ユーラシア大陸上のトラフが発達しやすくなる。<br>ユーラシア大陸上のトラフの発達・未発達は、さらに、そこでの冬から春の積雪面積の偏差の形成という物理過程を通して、次の夏のアジアモンスーンの偏差に影響することが示された。即ち、MAOSと偏西風レジームが結合したこの気候システムでは、弱い(強い)夏のモンスーンの後の秋には、(逆)PNAパターンが持続し、続く冬にはユーラシア大陸上に少(多)雪をもたらす循環場が卓越することにより、次の夏のモンスーンは、強い(弱い)状態になるという、2年振動的傾向を持つことがしめされた。このように、MAOSと中・高緯度の偏西風レジームを含む気候システムの準2年振動的変動の機構は、アジアモンスーンを媒介とした、熱帯と中・高緯度のあいだの、季節を違えた相互作用によることが強く示唆される。<br>さらに、現実のより非定常的なシステムの振る舞いと、ENSOのように上記の準2年振動が増幅された状態の物理的な理解には、ENSOとは全く独立な振動系として指摘されている北大西洋振動(NAO)の、このシステムへのストカスティックな強制が非常に重要であることを示唆する観測的事実も提示された。

著者

和田 章義

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.99, no.6, pp.1453-1482, 2021 (Released:2021-12-16)

参考文献数

81

被引用文献数

5

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2018年、日本に上陸した台風チャーミーは進路転向後に急衰弱した後、数日間その強さを維持した。続いて台風コンレイはチャーミーによって冷やされた海域を急衰弱しつつ通過した。これら2つの台風が急衰弱した海域は、海洋中規模渦が豊富な海域である。これら2つの台風の強度変化における冷水渦の役割とその類似点及び相違点を理解するため、2km水平解像度非静力学大気モデルと大気波浪海洋結合により数値シミュレーションを実施した。また冷水渦の強度を観測により確証できないため、チャーミーの弱化に有意に寄与する規模を仮定した人工冷水渦を埋め込んだ海洋初期値及び日付の異なる海洋初期値を用いた感度実験を実施した。コンレイに対しては、日付の異なる海洋初期値の代わりに、9つの大気初期値に対するアンサンブルシミュレーションを実施した。2つのシミュレートされた台風の急衰弱における海洋場の役割は、どちらも台風通過時の海水温低下による海洋貯熱量の低下と関係していた。チャーミーとコンレイに対するシミュレーション結果のほとんどは、成熟期または衰退期の期間、過剰発達傾向を示した。チャーミーの過発達は不十分な海面水温低下により生じており、人工冷水渦は海水温低下の促進を助長した。一方でコンレイの過発達は台風進路シミュレーションの失敗に関連していた。コンレイの進路が適切にシミュレートされることにより、コンレイはより多くの時間、海水温低下域上を移動することとなり、鉛直シア上流側における地表面付近及びインフロー境界層、台風中心への内部コア域における水蒸気輸送の減少を通じて、弱化を強めることとなった。2つの台風に見られた共通点として、中心における下降流と関連する断熱加熱の減少が台風弱化と密接にかかわっていた。

著者

IKUTA Yasutaka FUJITA Tadashi OTA Yukinari HONDA Yuki

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

pp.2021-076, (Released:2021-09-14)

被引用文献数

7

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The regional data assimilation system at the Japan Meteorological Agency employs a variational data assimilation system on the basis of the non-hydrostatic model ASUCA (named ASUCA-Var). This paper reviews configurations and the current status of ASUCA-Var. To consider the consistency of analysis and prognostic variables, the control variables of ASUCA-Var include soil variables and basic atmospheric variables. The background-errors based on the control variables are calculated every three hours for land and sea grid points to better reflect the representative error covariance structure, taking into account daily variations and differences in structure on land and sea. Although the cost function is designed to be a perfect quadratic form, the basic field update method in the optimization process allows the nonlinearity of the observation operator and numerical weather prediction model to be incorporated into the solution of optimization problem in the incremental four-dimensional variational (4D-Var) method. The outer/inner models used in the incremental 4D-Var method are based on ASUCA, with suitable configurations according to each resolution and applied linearization. Observation operators are implemented for various kinds of observations used, with unified interfaces encapsulating external simulators. Variational quality control and variational bias correction are also introduced for advanced observation handling within the variational system. Parallelization is introduced to enhance computational efficiency, including adjoint calculations. To assess the impact of assimilated observations, degrees of freedom for signal are also available. In addition, as a system for operational use, ASUCA-Var is designed for sustainable development. The meso-scale analysis and local analysis workflows are presented as operational implementations of ASUCA-Var. ASUCA-Var improves forecasting in a wide range of validation indices. The major future improvements of ASUCA-Var include the introduction of the flow-dependent background-error and the extension of the control variable to hydrometeors, which are expected to enhance the prediction accuracy of the operational regional model.

著者

TAKAMURA Tamio KHATRI Pradeep

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

pp.2021-075, (Released:2021-09-06)

被引用文献数

1

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A rotating shadow-band spectro-radiometer system is a powerful tool for surveying light in the environment. It can provide the following spectral components of the solar irradiance without using any traditional solar tracking tool: direct normal irradiance (spDNI), diffuse horizontal irradiance (spDHI), and global horizontal irradiance (spGHI). Both irradiances, spDNI and spDHI, are derived from the combination of spGHI observations at different shadow-band positions. The shadow-band system induces basic errors caused by the imperfect corrections of the diffuse irradiance shadowed by band. To restrict the basic errors to within 2 %, the band slant-angle should be within 72 deg for a usual operating condition of the MS-700 spectro-radiometer manufactured by EKO Instruments Co., Ltd. with the MB-20 shadow-band system for MS-700. The errors in the spDNI and spDHI estimation are evaluated quantitatively by using realistic models that consider instrumental and atmospheric conditions. Estimates of spDNI can result in optical depth errors. The relative error in this estimation is described by using a correction coefficient Cfwd defined by the ratio of the true diffuse irradiance simulated by the shadowed irradiance to the approximate value observed. The value of Cfwd depends on the magnitude of the aerosol optical depth as well as the aerosol type. This error analysis should help to improve the accuracy of this system of measurements.

著者

YANG Wen-Ting FU Shen-Ming SUN Jian-Hua ZHENG Fei WEI Jie MA Zheng

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

pp.2021-074, (Released:2021-09-09)

被引用文献数

7

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At present, satellite-derived precipitation estimates have been widely used as a supplement for the real precipitation observation. Detailed evaluations of a satellite precipitation estimate are the prerequisite for using it effectively. Based on the daily precipitation observation from 91 rain gauges throughout Thailand during a 15-yr period, this study evaluated the performances of daily precipitation data of CMORPH and TRMM (3B42 version 7) in an interpolating-grid-points-into-stations manner. This filled in the deficiencies of the current evaluations of TRMM-3B42v7's performances over Thailand, made the first evaluation of CMORPH in this region, and showed the first report of relative performances of two datasets. For the entire Thailand, a total of 35 factors (including precipitation intensity, spatial distribution pattern, duration/interval) was used in the evaluation. It is found that only 12 of them (including annual and monthly variations of precipitation, conditional rain rate in rainy season, rainfall interval in entire year, non-precipitation days, etc.) were reproduced credibly (i.e., relative error was less than 20 %) by the two datasets. Both TRMM-3B42v7 and CMORPH displayed similarly poor performances in representing intensity and spatial distribution of extreme precipitation. Comparisons based on the 35 factors indicate that TRMM-3B42v7 displayed a better overall performance than CMORPH for the entire Thailand.  For each region of Thailand, CMORPH/TRMM-3B42v7 showed different performances in different regions (a total of 19 factors was used). The CMORPH/TRMM-3B42v7 data made credible estimates over all five regions of Thailand in terms of daily precipitation intensity and monthly variation of precipitation, whereas, in terms of precipitation day fraction, conditional rain rate during dry season, and interval/duration of rainfall events during the rainy season, it showed notable errors in all regions. Overall, TRMM-3B42v7 exhibited superior performances to CMORPH for the North, Northeast, East, and South of Thailand, whereas, CMORPH and TRMM-3B42v7 displayed similar performances for the Central Thailand.

著者

ARIAS Ivan CHANDRASEKAR V.

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

pp.2021-069, (Released:2021-08-12)

被引用文献数

3

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The cross-validation of radars in a network is important in making consistent retrievals across the domain and assuring the product quality. During the RELAMPAGO field campaign, two C-band radars, namely the Colorado State University C-band Hydrological Instrument for Volumetric Observations (CSU-CHIVO) and the C-band Scanning ARM Precipitation Radar (CSAPR-2), were deployed near the Sierras de Cordoba in Argentina, a region known for having some of the most intense severe weather in the world. In addition to these two radars, the operational radar of the Cordoba City, the Radar Meteorologico Argentino 1 (RMA-1), adds another instrument to the RELAMPAGO network. This study presents an intercomparison between the RELAMPAGO C-band radars using the GPM spaceborne radar as a common reference. A method to bring ground-based radars into better agreement is also proposed. Moreover, the attenuation correction for the C-band radar is studied in the context of intercomparing two radars. The attenuation coefficients are computed for the RELAMPAGO domain using the local disdrometers deployed during the campaign. After the attenuation correction, CSU-CHIVO, CSAPR-2, and RMA-1 compare well with GPM-DPR with a high correlation and bias less than 1 dB.

著者

Chao WANG Liguang WU Haikun ZHAO Qingyuan LIU Ji WANG

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.99, no.6, pp.1413-1422, 2021 (Released:2021-12-16)

参考文献数

46

被引用文献数

2

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Translation speed is an important factor determining locally accumulated disasters induced by tropical cyclones (TCs). We found that the basin wide TC translation speed over the western North Pacific (WNP) in the late season (October–December) experienced an abrupt decrease in the early 1980s. However, this slowdown cannot be explained by the previously proposed deceleration in large-scale steering. In this study, we demonstrated that this slowdown results from the decreased proportion of subtropical TC track frequency in the early 1980s. Because late-season large-scale steering flow in the subtropical WNP is much greater than that in the tropical WNP, TCs influencing the subtropical WNP generally hold greater translation speed than that of TCs staying in the tropical WNP. Thus, a decrease in the ratio of subtropical TC track frequency can lead to a notable decrease in the basin wide TC translation speed. The decreased ratio of subtropical TC track frequency results from the strengthened southwestward steering and the reduced ratio of TC genesis in the tropical eastern WNP, which is linked to a WNP anticyclonic circulation that appears to be driven by the Atlantic Multi-decadal Oscillation. The result introduces the crucial role of TC track shift in the basin wide TC translation speed and has important implications for understanding the effects of climate change on TC translation speed.

著者

清水 喜允 内田 亮

出版者

公益社団法人 日本気象学会

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.52, no.3, pp.289-299, 1974

被引用文献数

8

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日本海側の沿岸平野部の大雪と関連するうず状エコーの形成過程の研究が,適切な局地集中降雪の予報のために必要である.日本海で観測される雪のエコーパターンは,吹出し初期のランダムな対流セルの分布,最盛期の一般流に平行な縦整列線エコー,衰弱期の横整列線エコー,そして稀ででるがうず状エコーが特徴的である.<br>整列した線エコーパターンは多くは一般流に平行で,線エコー相互の間隔は平均30kmでエコー頂高度の約10倍であった.この結果は浅井(1968)の,バンド状雲列の間隔に関する理論的結論を支持する.<br>うず状エコーの観測される条件は,いわゆる里雪大雪の綜観場であるが(宮沢1967),著者は地上気圧場の日本列島に位置する曲率半径100km程度のシャープなリッジが存在し,風の鉛直シアーの場に著しい変化があることを指摘する.<br>二例の観測によって,うず状エコーは西から東にのびるバンドエコーに,北東から南西に走向する線エコーが斜交するとき,うえに述べた綜観場の中で形成されることがわかった.数個の高い対流セルが反時計廻りに回転し,リング状となり,うず状エコーの中心の眼になることが指摘される.

著者

和達 清夫 益田 クニモ

出版者

公益社団法人 日本気象学会

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.10, no.12, pp.670-675, 1932

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To see the general state of the seismic activity in the Kwant&ocirc;-district, where is noted by the frequent occurrence of earthquakes and especially by the Great Earthquake of Kwant&ocirc; (Sept. 1, 1923), North Idu (Nov. 26, 1930) and West Saitama (Sept. 21, 1931), the large earthquakes occurred in this district during the last 9 years are investigated about the position of their origins particularly taking account of the depth of focus.

著者

和達 清夫 鷺坂 清信 益田 クニモ

出版者

公益社団法人 日本気象学会

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.10, no.8, pp.460-474, 1932

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It has been generally known that earthquakes take place at any depth in the crust as far as about 500km. below the surface. For the investigation of near earthquakes, a standard table of travel time of seismic waves transmitted from the origin of variable depths is required to be made by the recent materials obtained in the seismometrical observation. For this purpose, the time-distance curve of the great earthquake occurred in North Idu district on Nov. 26, 1930 is adopted and the values of seismic wave velocity calculated by Mr. Honda are used in this paper. Thus, several tables of the travel time concerning the depth of focus and the epicentral distance are obtained. They are considered to be applicable for various branches of our practical seismology. Further, we have also calculated a table of the correction due to the depth of focus which must be applied on the travel time at a large epicentral distance in the case of distant earthquakes. As for further investigations of seismic wave propagation based upon the present tables, we shall write in the next report.

著者

和達 清夫

出版者

公益社団法人 日本気象学会

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.4, no.4, pp.86-91, 1926

著者

和達 清夫

出版者

公益社団法人 日本気象学会

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.3, no.8, pp.201-211, 1925

被引用文献数

1

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Some seismograms of the destructive earthquake occurred on May 23rd, 1925 in North Tazima district, show distinctly so-called the Mohorovi_??_i_??_ wave _??_. One of them is shown in Fig. (4) magnified from the seismograms of Wiechert's 200kg. seismograph installed at the Central Meteorological Observatory in Tokyo. (Epicenter distance about 450km.)<br>The author of the present paper has drawn the hodograph for the longitudinal wave P from the results of seismic observations of the meteorological stations in this country as well as the time difference between P and _??_ from seismograms of these stations in case when it revealed on it. Moreover the curve of _??_ is also drawn on the same diagram and is shown in Fig. (6).<br>Nextly, the author has assumed that, to interprete the time curve the discontinuity layer exists not so far from the surface in the earth crust. Following numerical values are obtained:-<br>Velocity of the longitudinal wave<br>above the discontinuity layer, <i>v</i>₁=5.56km. per see.<br>Ditto under the discontinuity layer, <i>v</i>₂=7.50km. per see.<br>Epicenter distance of stations where P<br>and _??_ waves arrive simultaneously &Delta;₀-120km.<br>Difference of T(P)-T(_??_), shown in Fig. (6) is 6.2 sec.<br>From these values, the depth of the discontinuity layer and that of the seismic foeus of this earthquake is determined. He has also compared the time of occurrence with those of the other two great earthquakes which have occurred on Jan. 15th, 1924 and Sept. 1st, 1923 respectively in Fig. (1); and ascertained that the geographical effect is not so great in these time-curves that the following conclusion may hold good in its main figure, even in any earthquake which occurred everywhere in this country.<br>Followings are main results obtained in this paper:-<br>(1) So called &ldquo;initial movement&rdquo; takes place with sudden change in its magnitude, and sometimes in direction, at the place about 100-200km. distant from the epicenter. Fig. (5).<br>(2) The epicenter distance above mentioned depends chiefly upon the depth of seismic focus, therefore the depth may be estimated by this means. <br>(3) I_??_itial movement must be very weak at the stations which lie within the epicenter distance, from 200km. to 1000km. approximately.<br>(4) For the determination of the direction of epicenter from that of the initial movement of longitudinal wave, it is better to use _??_ phase than P and this will be done with much accuracy and easiness. <br>(5) Depth of the discontinuity layer and that of the focus of Tazima-earthquakes are calculated and their values have been found to be about 42km. and 32km. respectively.<br>(6) S-phase of the transverse wave begin to appear gradually o_??_ seismogram and with increasing epicenter distance it becomes more distinct.<br>(7) Irregular form of isochronal curves may be considered as the effect of the discontinuity layer whose depth may not be definite in a part of the earth-crust of this part of the globe.<br>(8) Well known &ldquo;Omori's formula&rdquo; which expresses the relation between the duration of preliminary tremor and epicenter distance, may hold good with _??_ and _??_ phases for the region of small epicenter distance and with P and L phases at distant places.<br>The present paper is a preliminary report and the more complete studies will follow in a near future.

著者

和達 清夫

出版者

公益社団法人 日本気象学会

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.10, no.7, pp.397-401, 1932

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In this paper, is treated a simple geometrical method for locating the position of earthquake focus by the arrival times of initial phase observed in the seismograms of several stations near the epicenter. The propagating velocity of seismic waves is assumed to be constant everywhere in the crust, but some considerations are also made in the case that the velocity increases with the depth.

著者

和達 清夫

出版者

公益社団法人 日本気象学会

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.6, no.1, pp.1-43, 1928

被引用文献数

2

著者

和達 清夫

出版者

公益社団法人 日本気象学会

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.15, no.8, pp.295-316, 1937

被引用文献数

1

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In the present paper are treated the problems concerning the mechanism of earthquakes from the stand point of the seismological observation of earthquake waves. First of all the importance of generation of a fault is discussed for the occurrence of earthquakes. Then the fact so-called &ldquo;quadrant distribution of first motion&rdquo; which is observed in almost all cases of earthquakes of both shallow and deep origins can be considered as a naturally expected phenomenon if earthquakes occur first in the crust by breaking, in other words by fault, and the conservation of angular momentum be hold. Hitherto, oscillators are sometimes considered at the source of earthquakes to interpret the distribution of the first motion, such as &ldquo;center of compression or dilatation&rdquo; &ldquo;doublet with moment&rdquo; or &ldquo;a pair of doublet with (without) moment&rdquo; etc. Yet we have perhaps never heard of the simple explanation mentioned above that the distribution of the first motion can be interpreted by the motion caused by a doublet (with moment) and adding to it by that of the opposite sign caused by the reaction of the former.<br>Although the first motion of earthquakes can be considered to be caused by a pair of doublet oscillator, it is quite another phenomenon as to the crustal deformation observed in the epicentral region where sometimes a remarkable fault may be found in the case of large earthquakes. The latter phenomenon cannot be satisfactorily interpreted by the assumption that a pair of doublet nuclei of force act in the crust, but rather explained by the assumption that there exists only one doublet nuclei of force in the crust, each of them lies on each side of the fault surface in a certain depth.<br>A trial is made to obtain mathematically the crustal deformation at the surface occurred near the fault by a great earthquake. For the simplest case, the following assumptions are made. In a semi-infinite elastic body, surface. being <i>z</i>=0, the fault surface <i>y</i>=0 and <i>z</i> axis taken positive downwards, a nucleus of force exists at (0, -<i>b, b</i>.) and a force <i>X</i>₀ acts horizontally to <i>x</i>-direction, another nucleus at (0, -<i>b, b</i>), force acts there -<i>X</i>₀. As boundary conditions, stress must be vanish at <i>z</i>=0 and also at the fault surface <i>y</i>=0. The method used for this calculation is similar to that made by F. I. W. Whipple (M. N. of R. A. S. Geo. Sup. Vol. 3, No.6) and the approximate solutions obtained. The crustal deformation thus obtained resembles much to that actually observed.<br>In the last part, the problem of the wave propagation of shallow earthquakes is treated. Dr. H. Nakano treated theoretically this problem assuming oscillators in a general form at the origin. Dr. H. Honda proved that the actually observed result of seismic waves agrees just well with a special case of this theoretical result. Of couse this proof is good in general tendency but if we examine precisely the observed result, it may be found that the problem of propagation of seismic waves issued from a very shallow origin can not be treated under such a simple conditions as assumed by Dr. Nakano that the medium is uniform and perfect elastic and the origin lies just on the surface. He obtained that the amplitude of solid seismic waves decreases with epicentral distance as <i>A_P</i>&prop;&Delta;^-2, <i>A_T</i>&prop;^-1 in their principal directions respectively, and this theoretial result ascertained by Dr. Honda using many observational data. But in the practical case, the earth's crust is not homogeneous, the seismic-focus does not lie strictly on the surface and therefore the conditions of wave propagation must be somewhat different from this theoretical result.