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

---

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

---

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.

著者

和達 清夫 川瀬 二郎

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.14, no.8, pp.381-404, 1936

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This paper is composed of two parts. The first part deals with the general theory of long-period seismographs having a device of the mechanical registration and the properties of horizontal pendulum of Z&ouml;llner's befilar type. As to be convenient for designing these instruments we investigated about the style of the suspended bodies as well as the tension of the fibre in the equilibruim state. The results thus obtained are graphically represented in Fig. 3, 4 and 5.<br>In the second part is described an electrical methol which makes to record mechanically the motion of long-period pendulum with a sufficient magnification and without any frictional resistance. For this purpose we adopted a system of series, i.e. horizontal pendulum (seismograph)&rarr;coil (generator)&rarr;amplifier&rarr;recording galvanometer. The seismograph is similarly constructed in size and figure as Galitzin's one. The horizontal pendulum, having a mass of 10kg hanged with piano wires of 0.7mm in diameter, bears a coil (20, 000&Omega;) and alminium plate. Both lie in the magnetic field and serve as the generator and damper respectively. In this seismograph it is not so difficult to get a period more than 40 sec. the pendulum continues to freely oscillate for a long while without any considerable decrease in amplitude if the effect of the damper be properly taken away.<br>The recording galvanometer was specially designed for this purpose. It is of a moving coil type and bears a recording pen with a straw (strengthened by bakelite suffusion) style in order to get registration on a smoked paper (See photopraphs of Fig. 16). The resistance of this galvanometer is 5, 600&Omega;, the proper period of it 0.4 sec., the damping ratio <i>v</i>=4 in the case of open circuit. It causes a deflection of about 1cm. on the paper for a current of 0.1mA when the arm length is 16cm.<br>The current generated in the coil by earthquakes is in Galitzin's method lead to a long-period sensitive galvanometer and observed photographically, but here we magnified it by a voltage and current amplifier to get a current large enough to act the mechanically recording galvanometer of short-period mentioned above. The wiring of the amplifier is shown in Fig. 6. This amplifier consists of three stages of push-pull type directly coupled. Vacuum tubes B 228 and A 409 are used. The formers of earlier two stages are operated by 2 and 200 Volt storage battery and the latters of the last stage by rectified current obtained from 100 Volt A. C. line. We can obtain a sufficient stableness of this amplifier for the continuous routine observation and its adjustment and treatment are not so difficult. If the condensers used in this amplifier be omitted or changed properly for others of different capacity, we can get to some extent a desirable condition of amplification for the current generated by earthquakes according as its period varies. In a word, the magnification curve for stationary oscillations obtained by the present arrangement is very alike to that of Galitzin's instruments. But there are some inevitable defects because the recorded seismogram is magnified in very complex manner except when the earthquake motion takes place in regular oscillations, and even in this case a remarkable phase lag is observed for rapid oscillations.<br>In brief, our intension is to get the mechanically registered seismogram applied to the Galitzin's seismograph, because the photographic recording has various inconveniences for a routine work. Some examples of seismograms obtained by the present method are shown in Fig. 16. Of course there may be many things to be improved in our apparatus, it seems, however, to suggest that the registcring method of this kind may be useful for the routine observation of distant earthquakes by long-period seismographs, and also applicable to observations of other geophysical phenomena, such as terrestrial magnetism, earth current, wind, temperature and pressure of the air etc.

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.12, no.9, pp.496-497, 1934

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.11, no.11, pp.505-512, 1933

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This earthquake was precisely investigated by Mr. Isikawa in the last year. (this journal Vol. 10, No.4.) This report is a supplementary one to it, especially on the point of the focal depth and reflected waves, taking advantage of the travel time table calculated by the author and others.

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.9, pp.540-551, 1932

被引用文献数

1

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The velocity ratio of P and S waves is obtained by many authors to be nearly constant everywhere in the earth's crust. In the present investigatio_??_, is treated this problem by a method of <i>t_p-T_p-s</i> diagram which gives the relation between the arrival time of P and duration of (P-S). Examining in many cases of large earthquakes of both shallow and deep origins occurred in our country, the relation is obtained to be approximately linear as is expected, especially in the cases of deep-seated earthquakes. From these investigations, the velocity ratio of P and S waves is obtained as about 1.73 in the upper part, it may be probably the so-called Mohorovicic layer, but its value seems to differ in different localities; while, in the deeper part nearly a constant value of 1.79 is obtained. Thus, using the result we are able to obtain the depth of seismic focus by a simple method, especially in case of deep-seated earthquakes.

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.11, no.9, pp.389-394, 1933

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This report is presented for the purpose of showing the general activity of recent large earthquakes (1919-1928, Sep.) in the world. The materials were all taken from I. S. S. issued from the University Observatory, Oxford.

著者

大沢 綱一郎

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.36, no.6, pp.227-238, 1958

被引用文献数

3

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東支那海殊に九州西方海上で寒候季に起る突風は,温暖で静かな海面を急に襲うもので従来小さい漁船の脅威のまとであった.昭和30年の始めに多数の船舶の協力をえて協同観測を実施した結果,アメリカ合衆国でしばしば観測されるタツマキを伴う不安定線と同一と見られるものが東支那海にも存在し,雷雨を伴う発達した不安定線に.強烈な突風が伴うものであごるとがわかった.<br>また,暖候季殊に梅雨末期によく局地性豪雨があり,これも雷雨を伴うことが多いが,その場合雷雨細胞が一線上に並ぶ場合が多いものである.この雷雨細胞が一線上に並んだものの東縁を結んだものが不安定線である場合が多い.不連続線は寒暖両気塊の境界であるが,不安定線はそれとは別の場所で同一気塊内の対流現象の起る線であり,不連続線とは性質を異にする.<br>過去における長崎県のタツマキの数種も不安定線に伴うものであることがわかった.<br>不安定線通過に際しては,気象要素の急激な変化を伴うもので気圧の急上昇,気温の急降下,湿度の上昇,風速の急増(突風),風向の急変,雷雨現象(タツマキ)などが認められ,亦線の背後に雷雨高気圧とよばれる寒冷域が表現せられるのが普通であるが,之等を三つの実例,(1)昭和30年1月30日の突風(2)昭和31年8月27日のタツマキと雷雨,(3)昭32年7,月25日の豪雨と洪水によって示した.<br>昭和30年1月30日の冬の突風の例では,電光・雷鳴・ヒヨウ・アラレなど雷雨現象がもっとも発達した玄海灘で突風がもっとも強烈であったことから見ても冬の突風は雷雨現象と関連していることがわかる.この例では寒冷前線の前方約160キロメートルの処に寒冷前線にほぼ平行に不安定線が表現せられた.昭和31年8月27日の雷雨の場合には,佐世保で1時間の雨量102ミリという強烈のものでタツマキを伴ったものであるが,之等は不安定線に伴ったもので,その背後約70キロメートルの処に表現せられる寒冷前線上には著しい雲は認められないことが,運転を開始したばかりの背振山のレーダー写真に依って確認された.昭和32年7月25日の諫早方面の豪雨と洪水の場合には1時間100ミリ以上という強い雨が3時間以上も続いたものであるが,これは気象状態に地形の影響が加わって,はじめ対馬暖流にそうて走っていた不安定線がしだいに東西方向に傾いてついに停滞前線(梅雨前線)と一緒になり長い間動かなかったことに依るものである.<br>これら三例とも,いずれも雷雨高気圧が不連続線と不安定線の間または不安定線の背後に表現されている.対馬暖流上では平常は気温は周囲よりも高温であるのが普通であるが,対馬暖流上で雷雨高気圧が発達する場合には気温は周囲よりもかえって低く表現せられる.雷雨高気圧の寒冷部分は上層からの吹きおろし(Downdraft)によって生ずるものであり,上層の強風がDowndraftにより吹きおろされたものが突風であると推定される.不安定線は,対馬暖流以西の海上で発生しはじめ,対馬暖流上にきてもっとも発達することが多いのは暖い海面の影響に依る所が大きいのであろう.冬の突風の場合には,対馬暖流上で発達した不安定線はその勢力をしばらく維持して九州西沿岸を襲うが内陸に入ると地面摩擦のため,また冷却のために衰弱する.一方,夏の雷雨の場合には,九州の内陸に入り益々発達する傾向があるのは,夏の内陸の加熱作用と地形の影響による所が大きいためであろう.殊に第三の例では,Downdraftによる寒気が地形の影響を受けて不安定線を発達停滞させ諫早大水害のような惨事のもととななったことは特筆に値する.

著者

河角 廣

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.5, no.11, pp.232-240, 1927

著者

S. Manabe

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.34, no.6, pp.308-320, 1956-12-25 (Released:2007-10-19)

参考文献数

15

被引用文献数

17 20

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whether does the heat released by condensation actualy affect the large scale pattern or not? In order to answer this question, we examined the conservation of the potential vorticity and potential temperature in rainly regions for 12 hr period. At the same time, computing the 3-dimensional distribution of 12 hourly condensation by using the continuity relation of water vapour, we estimated the expected amount of the individual change of potential vorticity, and compared it with the observed one. As an example, a case of medium intensity of rainfall was taken, and it was found that the change of potential vorticity in the condensation region was small and hardly detectable. However, for the second case, when the extremely intense and large scale precipitation occurred, considerably large change of potential vorticity which has the same sense with the expected one is observed. Finally, the quantitative discussions about these two cases are performed.