Geomagnetic Storm Sudden Commencements Data (All ftp)

Geomagnetic Storm Sudden Commencements (SSCs) and Solar Flare Effects (sfe) measurements are provided by Observatorio del Ebro, Roquetas, Spain. The SSC and sfe are from magnetograms of the worldwide network of magnetic observatories. The stations, together with their abbreviations, are given in the series IAGA Bulletin No. 32 which contains the yearly compilations of these data. The International Service of Geomagnetic Indices (ISGI) maintains an up-to-date website. The old definition, that an ssc is a sudden commencement of a magnetic storm, is now changed into sudden commencements followed by a magnetic storm or by an increase in activity lasting at least one hour.

The Earth's geomagnetic field is impacted by solar activity. The Sun is in constant turmoil, with bubbling gases in strong magnetic fields. The solar wind pushes on the Earth's magnetic field, compressing the field lines on the sunward side of the Earth. The constant churning on the Sun occasionally leads to huge explosions of solar flares and coronal mass ejections (CME) in the vicinity of large active regions. When the Earth is in the path of these CME explosions, sudden increases are observed on ground-based magnetogram records when the collision occurs. A worldwide network of stations report these occurrences monthly. Father P. Mayaud compiled an extensive listing of these events, published in the IAGA Bulletin No.33 issue -- A Hundred Year Series of Geomagnetic Data 1868-1967, derived from the ground-based magnetograms. NGDC converted these published data to digital form as part of a data rescue effort. Additional year's data are added as they become available.

• Description of the data (text) -- Data are from IAGA Bulletin No. 33 A Hundred Year Series of Geomagnetic Data 1868-1967 by P.N. Mayaud.
  • Data format (text)
  • 1868-1967 data (ASCII) -- includes the date of SSC, amplitudes of the H and D components for the North (N), South (S), and combined (total -- T), amplitudes projected in the X and Y directions of the geographic coordinate system, amplitudes projected in the Xprime and Yprime directions of the dipole system, and the amplitude computed from the observed H amplitude and corresponding to the amplitude on the dipole meridian by supposing that, at such latitude, the SSC is a pure magnetospheric effect. Other quality indices are also included.
    
    

• Description of the data (text) -- Data are from IAGA 32 Bulletin series and from ISGI. Revised data for 1968-1975 were taken from IAGA Bulletin No. 39, SUPPLEMENTARY GEOMAGNETIC DATA 1957-1975, by P.N. Mayaud and A. Romana, IUGG Publications Office, 1977. o SSC amplitudes and duration data were added to 1976-1989 data. These data were also updated using the IAGA Bulletins No. 32 series which contain the final IAGA data. In some cases, SSCs in the earlier list disappeared (see explanation for change in the definition in text below). o Data after 1989 are still preliminary.
  • Data format (text)
  • 1968-present data (ASCII) -- includes the date of SSC, the number of stations reporting the event (A=very remarkable event; B=fair, ordinary, but unmistakable; C=very poor, doubtful), the number of stations reporting a sudden impulse (si) event which could not be classified as SSC), the average duration in minutes and the average amplitude in nanoteslas.
  • Number of SSCs by year and month 1953-present
  • Number of SSCs by year 1868-present
    
  • PDF versions of the monthly SSC tables that appear in the monthly report Solar-Geophysical Data (SGD) are available from the year 2000 to the present.
    

• Description of the data (text)
  • Daily storms observed in annual files
  • Format of the data reports -- freeform format
  • List of stations
    • 1966 1967 1968 1969
    • 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979
    • 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989
    • 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999
    • 2000 2001 2002 2003 2004 2005 2006 2007 2008
      
    • PDF versions of the monthly Principal Magnetic Storm tables that appear in the monthly report Solar-Geophysical Data (SGD) are available from the year 2000 to the present.
      
  • Station reports values in one x-y plot file
    • X-Y Plot File 1966-present

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