Kamiyama  Hiroshi

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Kamiyama, Hiroshi

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Variation of the Effectiveness of the SolarFlare according to its Location.著者 Kamiyama  Hiroshi雑誌名 Science reports of the Tohoku University. Ser.5, Geophysics巻 4号 1ページ 1-4発行年 1952-06URL http://hdl.handle.net/10097/44475         Variation of the Effectiveness of the Solar Flare                    According to its Location                         By Hiroshi KAMIYAMA                        Geophysical  Institute,  FacultyofScience,  TOholcu  University                                (Received April 19, 1952) § Introduction occurred in the wireless circuits from San     Sudden radio fade-out is considered toFransisco, Manila, and the domestic regions. be caused by the severe absorption i the DTherefore,  15 per cent of the whole number region or in the lower egion of the E-layer, of the eruptions were followed by sudden dueing to the abnormal ionization which isfade-outs. As to the important kind of erup- produced by the ultra-violet radiation with tions, 14 cases were accompanied by fade-outs, which the bright solar eruption is  accompanied. and the proportion then was 41 per cent, that It is expected, however, that the effectivenesswas of  considerably frequent occurrence. of the solar eruption upon the ionosphere Dividing the solar disk into nine equi-varies according to its location on the solar sectorial regions, the number of eruptions and disk. The longitudinal effect of the eruption fade-outs, and the occurrence tendencies, foris desired to be analysed on the stand-point each of them are shown in Table 1. Fig.1 of the forecasting for the traffic conditions illustrates the variation of the effectiveness of of the wireless  circuits. eruptions upon the traffic conditions, and the     A statistical method is adopted for this ordinates xpress the percentages againstthe investigation using the data which have been maximum value. When the fade-out corres-prepared by Ionosphere Research Committee ponds to two or more ruptions, it is difficult in Science Council of Japan. This Committee to distinguish t e effective one from them; made the nineteen co-operative observations values including those apprehensive cases are during last four years.  In this period, 640 shown by circles and the broken-line, while eruptions were observed and 34 eruptions were those of the favourable cases are by dots distinguished from them as the important and the full-line in Fig. 1. The maximum kind by Tokyo Astronomical  Observatory. value of the occurrence tendency is 10.4  %in                                        the central sector (10°E-10°W) concerning with§ Sudden Radio  Fade-out                                        onlytheprecise cases: and including whole     In good hours when the solar observa- cases, that is 23.7  % in the region 11°E-30°E. tions were carried on under the favourable The number of the eruptions ofthe important condition ofthe weather, 95 sudden fade-outs kind is too small to draw the curve.  2 H. KAMIYAMA         'At00% --I too %           ll                                                          1       Ail  mil   BO.      ll  A  •so     i• •                                                             . 60      )iA,IIklE06°           11. ,.. 40   t40    :  •  1 .    -   • 20 20  W  30  73 50 30  r0  c  .3 3) 50  70  90  E W 90 70  50 30 10  c  10 30 50 70  90  E          Fig. 1 Variation of the Effectiveness of the Fig. 2 Variation of the Effectiveness of the                  Eruption deduced from the Sudden Eruption deduced from the Abnormal        Fade-out. Absorption.  Table-1 The Effectiveness of Eruptions upon the Traffic Conditions of the  Wireless Circuits.             West East            Longitude                            90-71 70-51 50-31 30-11 10-10 11-30 31-50 51-70 71-90     No. of Eruptions  . 37 54 92 63 77 76 80 105 56        No. of the sure    Fade-outs 1 1 3 5 8 7 4 4 1        No. of the whole     Fade-outs 3 6 13 11 14 18 13 10 7         Occurrence      Tendency  (9) (sure) 2.7 1.9 3.3 7.9 10.4 9.2 5.0 3.8 1.8  -,•.• (whole) 8.1 11.1 14.1 17.5 18.2 23.7 16.3 9.5 32.5        Percentage to the    Maximum (sure) 26 18 32 76 100 88 48 37 17        (whole) 34 47 60 74 77 100 69 40 53                      Table-2 Occurrence Tendencies of the Abnormal Absorption.             West East           Longitude                            90-71 70-51 50-31 30-11 10-10  11130 31-50 51-70 71-90     No. of Eruptions 21 24 47 26 28 31 38 44 28         No. of Abnormal     Absorptions 4 6 18 10 14 16 13 12 9         Occurrence      Tendency (%) 19 25 38 38 50 52 34 27 32         Percentage to the     Maximum 37 48 73 73 96 100 65 52 62                 THE  EFFECTIVENESS OF THE SOLAR FLARE 3   §  Abnormal Absorptionwithin one per cent when the zenith distance  x is inferior to  75°. Assuming the particle       At many occasions accompanying with the density of the sun's atmosphere to be   eruptions, the echo of the ionospheric sounding                                                         n  is abnormally absorbed dueing to the similar                                         the total number of particles in the column in   mechanism to that of the sudden fade-out.                                          any direction x is as follows;   For each  equi-sector, the occurrence tendencies   of these phenomena are examined using the N noe°4 dx   data which were obtained during recent two                                                        dh  years. The numbers of the eruptions and of  =  nbe-tm  COS  x  these abnormal  absorptions are shown in   Table 2 and the variation of the effectiveness no 1                                                              0 cosx  of the eruption is  illustrated in Fig. 2 according   to the  longitude.where  0 is a constant, h is the height above                                             the sun's surface, and  no is n when  h = 0.  §  Discussion and Conclusion The initial intensity  Jo of the radiation is then        According to these results, it is concluded reduced to  Ix in the direction of x.   that the effectiveness of the solar flares upon  1;:  Ioe"  ,   the ionosphere, and consequently upon the tra-  ffic conditions of the wireless circuits, is most where  k is the absorption-coefficient. Then,   remarkable in the central region  (30°E-10°W), no 1 \                                                                     --6 cos x•   and is reduced by half beyond both 50° meri-                                               Ix = To exp  (— k   dians. It may be also noted that there seems Hence, we have   some asymmetries of the effectiveness with       .1"   regard to the  central meridian . The conclu-expk211—o                                        rxz=00 (  cos  x  —  1)P   sion is also confirmed by examining the data   of fminE. where  Ix-0 is  I, when x = 0. The broken line        Forecasting for the traffic conditions of in  Fig.  3 shows the numerical results of  /x/h.-o,   the wireless, one must be careful for the active taking for  knojO to be 2.5. The full-line is   regions within 30° meridians on the solar disk. drawn by plotting the squares of the avera-      Since the magnitude of these phenomena geing percentages in Table 1 and Table2.   is considered to be proportional to the square-  root of the intensity of the radiation from the   sun, the statistical results mean that the ultra- •                                                                                                                                              o'   violet radiation accompanying the solarflare   modifies its intensity according to the direction   before arriving at the earth's atmosphere.            ),\                                                     This is perhaps mostly due to the absorption-)4N\\r   suffered in the sun's atmosphere, and to some _  r/   extent due to the  directional character of the    radiation.  -  Su,  -       For  the  simplicity  of  the  computations,  Fig.  3  Variation  of  the  Intensity of the Radiation    we may regard the sun's surface as a plane. accompanying the Eruption according to   The error dueing to this simplification is the Direction.  4 H. KAMIYAMA           The variation of the effectiveness of the 3, 4, 5) in  Czechoslovakia.        solar flare is partly explained by the In conclusion, I wish to express my        absorption in the sun's atmosphere, but the sincere thanks to the members of Ionosphere       extent of this depends largely on the value of Research Committee in Japan for their        kno/O. Since the observed results show the arrangements of many data. It is also noted       asymmetry, it is probably a  Iact that there is with thanks that the research was helpedby       the directional character of the radiation from the Scientific Research Expenditure of the       the solar flare. The results may also refer to Department of Education.       the studies by J. KLECZEK and F. LINK 2,                                                      References         (1) F.  LINK & J.  KLEczEK Bull.  Central Astr. (4) F. LINK  : Bull.  Central  Asti. lust.  Czechoslovakia  Inst. Czechoslovakia 1,  p.69 (1950)  2, p. 140  (1951)        (2) J. KLECZEK  : ibid. p. 151  (5) J.  KLECZEK : ibid.p.180         (3) F. LINK  &  J.  KI:ECZEK  : Z. f.  Astroph.  29,  p. 304  (1951)  •

Variation of the Effectiveness of the Solar Flare according to its Location.

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Variation of the Effectiveness of the Solar Flare according to its Location.

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