Kato  Yoshio

Takei  Shigeo

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Kato, Yoshio

Takei, Shigeo

Tohoku University Repository (TOUR) / 東北大学機関リポジトリ

Geomagnetic Disturbance accompanying the HighAltitude Nuclear Deto-nation at JohnstonIsland on July 9th.1962著者 Kato  Yoshio, Takei  Shigeo雑誌名 Science reports of the Tohoku University. Ser.5, Geophysics巻 15号 1ページ 7-32発行年 1963-05URL http://hdl.handle.net/10097/44645 Geomagnetic Disturbance  accompanying the High  Altitude  Nuclear      Detonation at Johnston Island on  July 9th, 1962     By Geophysical YOSHIO KATO and  SHIGEO TAKEIInstitute, Faculty of Science,  TOhoku University    (Received March 20, 1963) Abstract           In this paper the authors treat the propagation of the isotropic mode of the      hydromagnetic waves in the magnetosphere and calculated the travel-time curve of      that wave emitted from various sources and compared it with the time of commencement      of the geomagnetic disturbance accompanying the high altitude nuclear detonation      at Johnston Island on July 9th, 1962. Since the observed delay time was too short,      the mechanism of magnetic transient variations produced by this high altitude      nuclear detonation is not simple. 1 Introduction    A high altitude nuclear detonation was exploded in the vicinity of Johnston Island,  16.7N'-169.4°W, at  09h00''.09s U.T. on  July 9th, 1962. Detonation height was reported to be about 400 km. Its effects on the earth's magnetic field were recorded at all magnetic observatories in the world.    In this paper we treated the propagation of the isotropic mode of the hydromagnetic waves in the magnetosphere assuming its various sources, and calculated the travel-time curves theoretically and compared them with the time of commencement of the geomagnetic disturbance because its first movement had been supposed as a hydro-magnetic impulse. But the observed delay time was too short, therefore it appears that no simple explanation of the magnetic distrubance can be expected. 2 ALFVEN wave velocity in the magnetosphere    The first impulse observed on the magnetogram is expected as the fast elementary  hydromagnetic impulse, radiated from the source area.  Therefore we can adopt the ray path theory only to discuss the distribution  of the time of commencement of the magnetic impulse observed on the  magnetogram. In this case we treated the propaga-tion of the isotropic mode of the hydromagnetic wave.    To find the distribution of ALFVEN velocity we constructed the model atmosphere above F2 region under the following assumptions;    1) The atmosphere has a spherically layered structure.    2) The isothermal diffusive equilibrium state.    3) The velocity distributions of ions and electrons are isotropic.    4)  H+,  He+,  0+ and electrons are considered as composition.    5) Electrical nutrality.8 Y. KATO and S.  TAKE1    Under these assumptions we calculated the distribution of number densities of the ions above the reference level of 500 km. (Fig. 1) The initial values at this level are shown in Table I.    Below the reference level to 210 km, reference was made to the model adopted by H. Kamiyama which consisted of  0'  ,  02+ and nutral atoms and molecules.                 Table  I.  Number densities of the ions at the referencelevel                                                   (after BATES & PATTERSON)             H+  He± Temperature  Number/cm3  1.8  x102  4  x  103  1  4  x  10311250°K  km  104-   8  :  \ H  +  6                 5 --             4 -         3         2  AtaHe:  I  • 0+  .1  8  cs  6  4  3  2I  0102 2 E _..  c  0  :e cr I 3  4  5  6 Fig. 1  1 x104  8   6 -  5   4 -   3 -   2 --    3 lx10 8  =    6-   5 -  4 - 3=    2-     2 8  103 2 3  4  5  6  8  104  Number/cm3  . Distribution of ions in2the 3  4  5  6  8  105 2 lower exosphere3  4  56 8106Fig. 2.Ixico  I  i I I I  FIIII  r  .1  1    1x107 2 3  4  5  6  81)(109 2 3  4 5  6 81x109  Allven Velocity VA cm/sec Distribution of  Alfven Wave Velocity in the lower exosphere     GEOMAGNETIC DISTURBANCE ACCOMPANYING NUCLEAR DETONATION 9    Fig. 2 shows the calculated value of  Alfven wave velocity in the lower exosphere of the above stated composition after assuming that the magnetic field is the dipole magnetic field.    As the figure shows the maximum velocity, about 2500 km/sec, is held at the height of 3300 km and a low velocity layer is above the F2 peak. 3 The ray path and travel-time    The ray path which is supposed to represent the initial disturbance should  be determined from the condition that the travel time T along the ray path is minimum.    Thus the travel-time T [r], must be at the minimum in the propagation. (Fig. 3) ‘00.1! 9,7  secho 90° so. 3/o.        $.,  Eno..-ose  s  17.9* .1.;° 3.;     9.6\ ,to.413:s3Z. \ \ source the earthspread angle ofregion sourceFig. 3. Schematic showing of ray path geometrywhere     T (9))] f ds               J  VA VA is the velocity of ALFVEN 14,1-1/72+  r'2  do  h,  V  (r) wave and is r,dr   d(l) =j  F  (r  •  r')  d (1)  00  1/B021  47r0  , and(1)whilewhere  [F],  6T =rF (r, r') is the first variation of T, and101,1[F],   0   + [Fr  Zri#1  -10c o (2)10 Y. KATO and S. TAKEI  oF  Fr'  —    The first term of equation (2) must vanish for the permitted paths. Therefore we can yield EULER'S equation.                     =  oF d   (  OF0           )                                 d(ay'    This equation is easily integrated when  aFilap=o  , that is;  F  —  r'  Fr'  =  C (3) C is an integral constant and determines the behavior of the ray path. From equation (3)                       dr  ri/r2  — C2V2 (r)   +  (4)                 diri)CV(r)    Double sign in the equation (4) indicate that two symmetric paths for the source are permitted for the same value of C.    We take conveniently the plus sign for the expression of ray paths. Thus,  CV  (r)  dr                =,(00) Vr2 — C2 V2 r (5)                 fr(h) r dr     T =(6)                              ,(00) V (r)-vir2C2 V2    It is mathematically clear that the actual paths are restricted within the region satisfying the condition  r2  c2  v2  (r)  >  0 (7) and the total reflection occurs if the equal sign is held, since such a point is the branch point of the ray paths.    To determine the parameter C, the boundary conditions at source area and the observation point is considered as follows.  8r  = 0 at  4) =  chi (observation point) fixed condition  8r * 0 at  =  rho (source area) free condition             for  ro  <  r<  Yo, where  ro and  To are the upper and lower bounds                          of the source    From the second term of the equation (2) we have          r'r       Fr'  =C—  0 atcbo (8)           rrC2d4,    This implies that the fast path must start with the rectangular emergent angle. Connecting the equation (4) and (8), C is determined as follows;GEOMAGNETIC DISTURBANCE ACCOMPANYING NUCLEAR DETONATION 11 C=r  ('0) v(r(1,0)) (9)But in the case of point source, C is not determined. In this case a path starting from the boundary of the source i.e.  r(60)="fc, or  ro, C is not restricted and is chosen freely. But since  (/) and T depends on C uniquely, the travel-time curve is determined uniquely for the given point  (r-----ri,  (/)=-(/),).    To calculate numerically, we adopted the following equation, equivalent to the equation (5), as it is known as SNELL'S law in the polar coordinate.  r  sin  i  -  =  C (10)  V where i is the incident angle, at first the paramenter C is determined by the equation (9) and the mesh of the integration was chosen as  1/500 earth radius.4 Numerical results*    Fig. 4 shows the calculated travel-time cruve. In show the case of point source and full and dotted lines 1 t.)  a)  in I- SeC5 4 3 2 0 9  $ 7 6 5 4 3 2 0 0 u  0 ///'  /,'  ./11 ,f fthe showfigure the the case ofchain lines the sources                c‘s                .g.'C.                        to.'  „ '  7. .°                V ''V  ''7 ,               'V '  V'.7 '7        7''7V .........,1'    ''Z ' ' .........".,..." „...' ZrZX.........., ,.... ......                                     ...... ...... . ,....              ... .... , ,.. A p • ,' , ,' 3  h, ,,, ..,, ....„.                                          4 ,   point source  spread  anglei0°  20°  ho= 20 Km 2ho= 300 Km 3 ho = 400 Km 4ha= 500 KmFig. 30°  60° 90'  120°  150°  4,0 4. Calculated travel-time curve:    the solid lines correspond to the source angle  20°    the  dotted•lines correspond to the  source  "angle  10°    the chain corresponds to the case of point source 180°  * These calculations were carried out by means of the electronic computer  SENAC-1, of Com-puting Center,  TOboku University.12 Y. KATO and S. TAKEIwhose spread angle of the source is 20° and  10° respectively, and nearly parallel curves in each case correspond to the assumed heights of the exospheric base which is taken to be 210 km, 300 km, 400 km and 500 km respectively and we assumed that the energy of the hydromagnetic wave is propagated electromagnetically below these heights.    As the figure shows, the difference between the case of point source and others is large. This depends on the boundary condition in each cases.    The effect of the difference in spread angles of the source appears in shifting the curve horizontally along with the coordinate of time T. While the effect of the difference in assumed base of the exosphere appears in shifting the curve nearly vertically along with the coordinate of distance.5 Observed data and discussions    The initial movement on the normal run magnetogram due to the detonation is sufficiently  large and observed at almost all the magnetic stations over the world but unfortunately it appears likely in the hour mark gap.    Furthermore because of the low chart speeds it was difficult to detect the accurate time of commencement.    But the specially provided magnetometer at the Victoria Magnetic Observatory recorded the commencement of the movement. B. CANER and K. WHITHAM reported and discussed the detonation effect on the geomagnetic field and concluded that the hydromagnetic wave propagated much faster than expected from the mean theoretical velocities and they suggested that it may not be reasonable to describe the propagated distrubance in terms of simple  hydromagnetic waves.    Besides the Victoria data the La-Cour type magnetogram in the United States Zone and induction magnetogram in Japan or France and other countries are available to determine the commencement time of the movement although the accuracy of the timing is not so high.    SELZER reported the observational results of the detonation effect on the magnetic field and concluded that the microstructure of the perturbation looked about the same at the stations in France and he reported that the signal reached the whole world in less than a second and concluded that at least the front part of the signal may have a electromagnetic nature.    While Fig. 5 shows our calculated travel-time curve in case that the spread angle of source is 20°, and the base of the magnetosphere is 500 km or 400 km, compar-ing with the observed commencement time of distrubance at various stations in the world.    As the figure shows, the observed delay time is much shorter than the calculated value in the distant stations. Therefore it is suggested that the propagated disturbance is not explained in terms of simple hydromagnetic waves and it may be considered that the disturbance propagated electromagnetically in its most part of the path in or below the ionosphere. But the accuracy of the timing of the records is not sufficient to give a definite conclusion.GEOMAGNETIC DISTURBANCE ACCOMPANYING NUCLEARList of StationsDETONATION  13Ho Sh Gu Si V Co  Cl  P  B Tu A  F  Ot Cf TaStation Distance  Travel TimeHonolulu Shimosato Guam Sitka Victoria College China Lake Point Barrow Brisbane Tucson  Adelie Fredericksburg Ottawa Wingst Chambon  la  Forret Tamanrasset11° 430  45°  48°  50° 51°  55°  56°  57°  58° 86°  91° 93° 137° 142° 169° (sec)I -5 4 3 2 0 9  8 7 6 5 4 3 2  0 A 4 - 0.1   2.9    2.5   2.4   2.2  Li   1.5±1.5   4.6   1.0±1   2.9   3.0±1.5   2.3±2   3 ±2   0.8±2- 0 .2±0.2  <  4 IN 1  ToFig. 5. 0°  30°  60° Observed data with calculated angle of source is 20°,  h0, the and 400  km (upper)  90°  120°  150* theoretical curve in the case base of the magnetosphere, is 180° that the 500 kmspread (lower)Acknowledgement    We would like to express our hearty thanks to the directors of the magnetic observatories in the world who kindly sent us useful copies of the magnetograms.    Thanks due to Dr. B. CANER of the Victoria Magnetic Observatory, and Prof. E. SELZER and Prof. W.E.  McNicoL of the University of Qeensland for their interesting discussions.    The authors express their sincere thanks to Captain ROBERT A. EARLE of the U. S. Depertment of Commerce, Coast and Geodetic Survey for the valuable copies of rapid-run magnetogram in the United States.14 V. KATO and S. TAKEIReferencesB. CANER and K.  WHITHAM  : A Geomagnetic Observation of a High-altitude Nuclear Detonation.        private communication but will be published in Canadian Journal of Physics.J. ROQUET, R.  SCHLICH and E. SELZER: Reception quasi-simultance en France, a Kerguelen et en        Terre  Adelie de la perturbation du champ  magnetique terrestre  engendree par       l'explosion nucleaire spatiale du 9 Juillet 1962.  Academie des Sciences,  Seance du        13 Aout  1962. R.W.E.  McNicor., and J.S.  MAINSTONE  : Geomagnetic Effects of Johnston Island High Altitude        Thermo-Nuclear Explosion of 9th, July, 1962 (private communication).  B.  J. FRASER: Geomagnetic Micropulsations from the High-Altitude Nuclear Explosion above        Johnston Island. Journal of Geophysical Research, Vol. 67, 4926, 1962 R.C. BAKER and W.M. STROME: Magnetic Distrubance from a High-Altitude Nuclear Explosion.        Journal of  Geophysical Research, Vol. 67, 4927, 1962. R.R. UNTERBERGER and P. EDWARD  BYERLY  : Magnetic Effects of a High-Altitude Nuclear        Explosion. Journal of Geophysical Research, Vol. 67, 4929, 1962.  EDWARD V. ASHBURN, JAMES P. LEE, and RAY N.  FRANCIS  : Observations of the Changes in        the Earth's Magnetic Field Induced by the High-Altitude Nuclear Explosion of       July 9, 1962. Journal of Geophysical Research, Vol. 67, 4933, 1962.GEOMAGNETIC DISTURBANCE ACCOMPANYING NUCLEAR DETONATION 15 HONOLULU,    HAWAIIJULY22 196281H I- I I165th M.T.  I1 22 D JULY 8 1962HONOLULU,      HAWAII  165th  M.T. •,I I HONOLULU,     HAWAII22165th M.T.JULY 8 1962   • 120Y16GUAM 150th  E.M.T. 1  1Y. KATO 1and S. TAKEI 191 I I H 20/61111==11^....1^11^110JULY 9 1962 GUAM150th  E.  M.  T.19  T  1 D  JULY 9 1962 IGUAM  150th  E.M.T.19-  '----i'i Z  1  20  1 1 JYLY 9 1962 GEOMAGNETIC DISTURBANCE ACCOMPANYING NUCLEAR DETONATION 17TUCSON, ARIZONAJULY 8,9 1962  2 isotet M.T. N-7-TUCSON, ARIZONA   150th M.T.JULY 8,9 19622      . , • ..•TUCSON,  ARIZONA 150th M.T.              •  zJULY 8,9 1962I 1 20118 Y. KATO and S. TAKEIJULY 8,   1962 9  24 1 SITKA  ,  ALASKA135th  M.  T:HI24JULY 8,9   1962 i SITKA,ALASKA  135th M.T. D IJULY 8,9 1962 4 SITKA,  ALASKA  135th.M.T.  z 1  20YGEOMAGNETIC DISTURBANCE ACCOMPANYING  1 COLLEGE,NUCLEAR ALASKA  1DETONATION150th  M.T.19JULY 8,9   1962 23JULY 231 1962  8'9  J  I COLLD3E, ALASKA 150th1:001>000023JULY  P  ,  9      1962 OLLEGI') ALASKA 150th  420 Y.JULY 231 8,9 1962KATO and S.  BARROWTAKEI  I 150th  W.  M.  T. FT BARROW 150th  W.M.T.I 23JULY 8,9     1962 DBARROW 1 23150th  N.M.T.JULY 8,9 1962 z 12011  1  1GEOMAGNETIC DISTURBANCE ACCOMPANYING 4NUCLEAR DETONATION  FREDERICKSBURG  ,      VA.21JULY 9 196275th M.T. HI IJULY 9 1962'A FREDERICKSBURG,     VA.75th  M.T. DJULY  9  19624 FREDERICKSBURG,         VA.    75th M.T. Z20Y6 z /0C e96I  6  XInP  VIdV t z F96I 6  ST.P SaTraqmy//I  P4. ••••^•• mmlb• 6 OS, 7961 6  4Inr  VIdV  a  a     ift't  ?961 6  JInr iatJactay /  0  G 296T 6  Atnt  VIdV MINIM= H ?c.,6T 6  WInr" 441.1aR117yGEOMAGNETIC DISTURBANCE ACCOMPANYING NUCLEAR DETONATION 23                  Induction  Magnetograa                             at  Sirnosato (  corractos)  h)lij    dD/dt9  dH/dt --------.  T  dVdt  -------.  f•^•^==.16 ^.    11 Le •        se3 INDUCTION  MAiNE  TO  GRAM  at  Onlawa. 430MMINENImis•mul  I.  -  •  ire D1  if  up        71/0110 (ff),,  I .  27/84.  (V im 111BRISBANE July 9 1962  Tracks I,  II and III  representing  pulsation in the    frequency range 0.01, to  0.1 c/s in E-W vertical    and N-S  components.  Tracks IV  records  pulsations in  N-S component in    the frequency range  0.1r-1 - 2 c/sGEOMAGNETIC DISTURBANCE ACCOMPANYING NUCLEAR DETONATION 25                , TAMAN  RA  ES  ET my 9 3962  V. VVI /INN \Neilltw\ifil\V\e‘i \r\#  41  NA .  v  •11%."...  ON X  WINGST  "  -                         ,Tuly9  3962.           4`.• • . ". 4 ' . ^-^ \   •,%',"-ndN''""21\o% V\."-•"•rs f•i\-***N1 , TAMANRAES  ET July 9  196,, I  I11"             ' le              It            It 11 WINGST                July 9 1962                        4 ,                              'Jo .61   -~2        rq TAMANRASSET July 9 1962  I  z  9  41'             ‘1"Nr  4`I                                             - -.1\00•001 Peare  ir\./%14Nnr\Sr VV. ft."     4'^ '"""\e, e"`" •••••04,40, i WINGST        •!  July  9 rmt1962        •^••••^•^^••^•Ab...../....   .^•••^^•^•^••••••• . -                                                     _ _ a.m....ammle.l^^••^•• 1^1111•1 ^IM^ 4}   ^•••=.1A.1111.1,...  ^IMmMI .11110w-I. C.C) NGEOMAGNETIC DISTURBANCE ACCOMPANYING NUCLEAR DETONATION 27H  Z D MENAMBErSU  43.3-siN  fix'  121E ONA&AWA  31.201  /4/•21rE A'AKIOKA  34'  bo'N  pleil,  E [coY501 [cot incr.  I Ina: or, [caiCOI [s° fso1dawn [5-' 50 5-[~~ I' Iskst  f! HIRAI  SO  3C'  21'W  1.0.3rE 5//405ATO  33'3eN  lieSCEASO  32.53'N  al'  orE KANOYA  3f•  23'N  130.  n'Eboe' [10/ -or incr incr. 7  8  (  U.77)9  10 11[IV (so[501 i aim dam dorm I7 8 9 10  11  (U.T) [ls'[5' [51*st 11111 1 Wes  f 7  8  9  (U.T)/0 11 DDo  H Ho t  zo Obis matoriuY. 19,6 GMT •  •KATO and S. TAKEI  'DinaJul II  lib  IS  III9 MLALearWINGST  Ef(ekt 1 POO  p••• OP ..OP II.  .      GEOMAGNETIC DISTURBANCE ..%11•^1/1\40.."411%^•=.04SIA".%.                                                   •  •   H M  EAN  OOK                      July 9 1962ACCOMPANYING NUCLEAR DETONATION 29  Port   Moresby .  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Geomagnetic Disturbance accompanying the High Altitude Nuclear Deto-nation at Johnston Island on July 9th.1962

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Geomagnetic Disturbance accompanying the High Altitude Nuclear Deto-nation at Johnston Island on July 9th.1962

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