Dst INDICES -------------------------------------------------------------------
Dst (Disturbance Storm Time) equivalent equatorial magnetic disturbance indices
are derived from hourly scalings of low-latitude horizontal magnetic variation.
They show the effect of the globally symmetrical westward flowing high altitude
equatorial ring current, which causes the "main phase" depression worldwide in
the H-component field during large magnetic storms.  This diskette contains the
hourly indices for the period 1 Jan 1957 through 30 Sep 1992, as derived by M.
Sugiura and T. Kamei, WDC-C2 for Geomagnetism, Faculty of Science, Kyoto Uni-
versity, Kyoto 606, Japan.

Hourly H-component magnetic variations are analyzed to remove annual secular
change trends from records of a worldwide array of low-latitude observatories.
A cosine factor of the site latitude transforms residual variations to their
equatorial equivalents and harmonic analysis isolates the term used as the
Dst index.  Sugiura described Dst derivation in ANNALS OF THE IGY.

               Dst INDICES RECORD FORMAT 1 Jan 1957 - 30 Sep 1992
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 Column  Fmt  Description
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  1-  3   I3  Index Name or Station Code
  4-  5   I2  Year (last 2 digits)
  6-  7   I2  Month
  8       A1  Geomagnetic Field Component H,D,Z,X,Y, or *=index, p=preliminary
  9- 10   I2  Day
 11- 16   I6  Reserved Area (all spaces)
 17- 20   I4  Tabular or Base Value (100 nT units for H,Z,X,Y and degrees for D)
 21- 24   I4  Value for  1st hour of day
   .
   .          H,Z,X,Y in units of 1 nT; D in units of 0.1 min
   .
113-116   I4  Value for 24th hour of day
117-120   I4  Daily Mean Value
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To obtain absolute hourly value add base value to entry.