Data Access
Kp, Sum_Kp, (3-hour) ap, and (Daily) Ap geomagnetic indices.
Kp and ap are 3-hour planetary indices and Sum_Kp and Ap are daily summed and averaged (respectively) indices created from Kp. These indices were created at the Geophysical Institute of Gottingen University through 1996, and at GeoForschungsZentrum (GFZ, Potsdam) subsequently.
GFZ, url given below, is the primary distribution site.
The web site of WDC for Geomagnetism at Kyoto U., url given below, offers plots and numeric downloads for Kp and related indices.
The data are currently (as of 12/07/2011) "final" from January, 1957, through December, 2008, and are "real time" thereafter, through the current day.
Alternative sources of many of the Kp and related indices include the hourly OMNI data set at NASA/GSFC/SPDF.
Worldwide Indices
The subscript p means planetary and designates a global magnetic activity index. The following 13 observatories, which lie between 46 and 63 degrees north and south geomagnetic latitude, 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
Kp index derives from Ks indices that 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.
Version:2.4.0
Kp, Sum_Kp, (3-hour) ap, and (Daily) Ap geomagnetic indices.
Kp and ap are 3-hour planetary indices and Sum_Kp and Ap are daily summed and averaged (respectively) indices created from Kp. These indices were created at the Geophysical Institute of Gottingen University through 1996, and at GeoForschungsZentrum (GFZ, Potsdam) subsequently.
GFZ, url given below, is the primary distribution site.
The web site of WDC for Geomagnetism at Kyoto U., url given below, offers plots and numeric downloads for Kp and related indices.
The data are currently (as of 12/07/2011) "final" from January, 1957, through December, 2008, and are "real time" thereafter, through the current day.
Alternative sources of many of the Kp and related indices include the hourly OMNI data set at NASA/GSFC/SPDF.
Worldwide Indices
The subscript p means planetary and designates a global magnetic activity index. The following 13 observatories, which lie between 46 and 63 degrees north and south geomagnetic latitude, 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
Kp index derives from Ks indices that 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.
| Role | Person | StartDate | StopDate | Note | |
|---|---|---|---|---|---|
| 1. | GeneralContact | spase://SMWG/Person/Hans.Joachim.Linthe |
GFZ's pages about Geomagnetic Indices and data links.
Web site descriing the IAGA-endorsed Kp, ap, Ap, Cp and C9 indices and the International Quiet and Disturbed Days. This site can be reached via DOI: the DOI ‘https://doi.org/10.5880/Kp.0001.
Description of the WDC file format for selected Kp-related indices
FTP download path of Kp and related indices at GFZ-Potsdam, including index documentation and history files.
HTTP download path of Kp and ap indices at GFZ-Potsdam.
Multi-option (html forms) access to Kp and related indices at Kyoto.
Last two digits of the year
Month (1-12)
Day (1-31)
Bartels solar rotation number - a sequence of 27-day intervals counted continuously from February 8, 1832
Number of day within the Bartels 27-day cycle.
Kp (planetary) 3-hour index for 0-3 UT
Kp (planetary) 3-hour index for 3-6 UT
Kp (planetary) 3-hour index for 6-9 UT
Kp (planetary) 3-hour index for 9-12 UT
Kp (planetary) 3-hour index for 12-15 UT
Kp (planetary) 3-hour index for 15-18 UT
Kp (planetary) 3-hour index for 18-21 UT
Kp (planetary) 3-hour index for 21-24 UT
Daily Kp sum of the eight Kp indices for the day expressed to the nearest third of a unit
Ap (planetary) 3-hour equivalent amplitude for 0-3 UT
Ap (planetary) 3-hour equivalent amplitude for 3-6 UT
Ap (planetary) 3-hour equivalent amplitude for 6-9 UT
Ap (planetary) 3-hour equivalent amplitude for 9-12 UT
Ap (planetary) 3-hour equivalent amplitude for 12-15 UT
Ap (planetary) 3-hour equivalent amplitude for 15-18 UT
Ap (planetary) 3-hour equivalent amplitude for 18-21 UT
Ap (planetary) 3-hour equivalent amplitude for 21-24 UT
Ap (planetary) equivalent daily amplitude - the arithmentic mean of the day's eight Ap values.
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).
C9 - a conversion of the 0-to-2.5 range of the Cp index to one digit between 0 and 9.
International Sunspot Number.
Records contain
Ottawa 10.7 cm Solar Radio Flux adjusted to 1 AU - measured at 1700 UT daily. 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.
Flux qualifier