Format Documentation of kpyymm.wdc Files
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Availability
The most recent kpyymm.wdc (yymm stands for year and month, each expressed
with two digits) files are distributed per e-mail half-monthly by
Dr. J. Matzka, mailto:kp_index@gfz-potsdam.de
Both recent and past tables (since 1932) are supplied as an archive on the
FTP servers
Germany: ftp://ftp.gfz-potsdam.de/pub/home/obs/kp-ap/
Denmark: ftp://ftp.space.dtu.dk/WDC/indices/kp-ap/
Background information on geomagnetic indices and the classification of days
can be found on the webpage (and links from there):
http://www.gfz-potsdam.de/en/section/earths-magnetic-field/services/kp-index/explanation/
Preliminaries
We use the standard format as published by the National Geophysical Data Center (NGDC) in Boulder, Colorado.
Caution:
* the columns for the solar radio flux (columns 66-71) are not reported from
2007 onwards
* the list of most quiet and most disturbed days is not contained in this
format; if you need those, please refer to the other tables
(kpyymm.tab)
* we do not guarantee the correctness of the international sunspot number
R; these values are published separately (Brussels, Belgium)
* note that the sunspot number calculation has been changed by WDC-SILSO,
Royal Observatory of Belgium, on July 2015, affecting sunspot numbers from
January 2015.
* sunspot numbers are not reported from 2015 onwards
The following scientific and format documentation is adapted from
ftp://ftp.ngdc.noaa.gov/STP/GEOMAGNETIC_DATA/INDICES/KP_AP/kp_ap.fmt
Selected Geomagnetic and Solar Activity Indices
Worldwide Indices
The subscript p means planetary and designates a global magnetic activity
index. The following 13 observatories now contribute to the planetary
indices: Lerwick (UK), Eskdalemuir (UK), Hartland (UK), Ottawa (Canada),
Fredericksburg (USA), Meanook (Canada), Sitka (USA), Eyrewell (New Zealand),
Canberra (Australia), Lovo (Sweden), Brorfelde (Denmark), Wingst and Niemegk
(Germany).
Three-hour-range Index Kp
Ks indices isolate solar particle effects on the earth's magnetic field;
over a 3-hour period, they classify into disturbance levels the range of
variation of the more unsettled horizontal field component. Each activity
level relates almost logarithmically to its corresponding disturbance
amplitude. Three-hour indices discriminate conservatively between true
magnetic field perturbations and the quiet-day variations produced by
ionospheric currents.
Ks indices range in 28 steps from 0 (quiet) to 9 (greatly disturbed) with
fractional parts expressed in thirds of a unit. A Ks-value equal to 27, for
example, means 2 and 2/3 or 3-; a Ks-value equal to 30 means 3 and 0/3 or 3
exactly; and a Ks-value equal to 33 means 3 and 1/3 or 3+. The arithmetic
mean of the Ks values scaled at the 13 observatories listed above gives Kp.
Equivalent Amplitude ap
The ap-index ranges from 0 to 400 and represents a Kp-value converted to a
linear scale in nT (nanoTesla) - a scale that measures equivalent
disturbance amplitude of a station at which K=9 has a lower limit of 400 nT.
Format Description
Column Format Description
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1- 2 i2 yy, last two digits of year
3- 4 i2 mm, month (1-12)
5- 6 i2 dd, day of month (1-31)
7-10 i4 Bartels solar rotation number - a sequence of 27-day
intervals counted continuously from February 8, 1832
11-12 i2 Number of day within the Bartels 27-day cycle
13-28 8i2 3-hourly Kp indices (0-3, 3-6, 6-9, 9-12, 12-15,
15-18, 18-21, 21-24 UT)
29-31 i3 Daily Kp sum, expressed to the nearest third of a unit
(supplied only for tradition, use Ap scientific purposes!)
32-55 8i3 3-hourly ap indices (0-3, 3-6, 6-9, 9-12, 12-15,
15-18, 18-21, 21-24 UT)
56-58 i3 Ap equivalent daily amplitude - the arithmetic mean
of the day's eight ap values
59-61 f3.1 Cp or Planetary Daily Character Figure - a qualitative estimate
of overall level of magnetic activity for the day determined
from the sum of the eight ap amplitudes. Cp ranges, in steps
of one-tenth, from 0 (quiet) to 2.5 (highly disturbed)
62-62 i1 C9 - a conversion of the 0 to 2.5 range of the Cp index to one
digit between 0 and 9
63-65 i3 International Sunspot Number. Records contain
* Zurich number through December 31, 1980
* International Brussels number thereafter
NOT ANY MORE REPORTED FROM 2015 ONWARDS
66-70 f5.1 Ottawa 10.7 cm Solar Radio Flux adjusted to 1 AU - measured
at 1700 UT daily and expressed in units of 10^-22 W/m^2/Hz.
Observations began on February 14, 1947. From that date
through December 31, 1973, the fluxes given here do not
reflect the revisions Ottawa made in 1966.
NOT ANY MORE REPORTED FROM 2007 ONWARDS
71-71 i1 Flux Qualifier
0: indicates flux required no adjustment;
1: indicates flux required adjustment for burst
in progress at time of measurement;
2: indicates a flux approximated by either
interpolation or extrapolation;
3: indicates no observation.
NOT ANY MORE REPORTED FROM 2007 ONWARDS
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For questions concerning specific data or the contents of this page, please
contact:
Dr. J. Matzka, mailto:kp_index@gfz-potsdam.de
Last modified: October 8, 2015