KP and AP values are taken from GFZ German Research Centre for Geosciences. The data can be obtained directly through GFZ: http://www.gfz-potsdam.de/en/kp-index The National Geophysical Data Center provides the observations here with no re- strictions on their use. Please contact us at the address below with your com- ments and questions about the form and the content of this information product or about the measurements themselves. NATIONAL GEOPHYSICAL DATA CENTER 325 Broadway Mail Code E/GC2 Boulder, Colorado 80303-3328 USA Telephone: (303) 497-6135 Telex: 592811 NOAA MASC BDR FAX: (303) 497-6513 ------------------------------------------------------------------------------- SELECTED GEOMAGNETIC AND SOLAR ACTIVITY INDICES ------------------------------------------------------------------------------- WORLDWIDE INDICES-------------------------------------------------------------- The subscript "p" means planetary and designates a global magnetic activity in- dex. The following 13 observatories, which lie between 46 and 63 degrees north and south geomagnetic latitude, now contribute to the planetary indices: Ler- wick (UK), Eskdalemuir (UK), Hartland (UK), Ottawa (Canada), Fredericksburg (USA), Meannook (Canada), Sitka (USA), Eyrewell (New Zealand), Canberra (Aus- tralia), Lovo (Sweden), Brorfelde (Denmark), Wingst (Germany), and Niemegk (Germany). THREE-HOUR-RANGE INDEX K------------------------------------------------------- K 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 al- most 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. K indices range in 28 steps from 0 (quiet) to 9 (greatly disturbed) with frac- tional parts expressed in thirds of a unit. A K-value equal to 27, for exam- ple, means 2 and 2/3 or 3-; a K-value equal to 30 means 3 and 0/3 or 3 exactly; and a K-value equal to 33 means 3 and 1/3 or 3+. The arithmetic mean of the K values scaled at the 13 observatories listed above gives Kp. EQUIVALENT AMPLITUDE----------------------------------------------------------- The a-index ranges from 0 to 400 and represents a K-value converted to a linear scale in gammas (nanoTeslas)--a scale that measures equivalent disturbance am- plitude of a station at which K=9 has a lower limit of 400 gammas. FORMAT FOR RECORDS OF SELECTED GEOMAGNETIC AND SOLAR ACTIVITY INDICES ------------------------------------------------------------------------------- COLUMNS FMT DESCRIPTION ------------------------------------------------------------------------------- 1- 2 I2 YEAR 3- 4 I2 MONTH 5- 6 I2 DAY 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. 13-14 I2 Kp or PLANETARY 3-HOUR RANGE INDEX for 0000 - 0300 UT. 15-16 I2 Kp or PLANETARY 3-HOUR RANGE INDEX for 0300 - 0600 UT. 17-18 I2 Kp or PLANETARY 3-HOUR RANGE INDEX for 0600 - 0900 UT. 19-20 I2 Kp or PLANETARY 3-HOUR RANGE INDEX for 0900 - 1200 UT. 21-22 I2 Kp or PLANETARY 3-HOUR RANGE INDEX for 1200 - 1500 UT. 23-24 I2 Kp or PLANETARY 3-HOUR RANGE INDEX for 1500 - 1800 UT. 25-26 I2 Kp or PLANETARY 3-HOUR RANGE INDEX for 1800 - 2100 UT. 27-28 I2 Kp or PLANETARY 3-HOUR RANGE INDEX for 2100 - 2400 UT. 29-31 I3 SUM of the eight Kp indices for the day expressed to the near- est third of a unit. 32-34 I3 ap or PLANETARY EQUIVALENT AMPLITUDE for 0000 - 0300 UT. 35-37 I3 ap or PLANETARY EQUIVALENT AMPLITUDE for 0300 - 0600 UT. 38-40 I3 ap or PLANETARY EQUIVALENT AMPLITUDE for 0600 - 0900 UT. 41-43 I3 ap or PLANETARY EQUIVALENT AMPLITUDE for 0900 - 1200 UT. 44-46 I3 ap or PLANETARY EQUIVALENT AMPLITUDE for 1200 - 1500 UT. 47-49 I3 ap or PLANETARY EQUIVALENT AMPLITUDE for 1500 - 1800 UT. 50-52 I3 ap or PLANETARY EQUIVALENT AMPLITUDE for 1800 - 2100 UT. 53-55 I3 ap or PLANETARY EQUIVALENT AMPLITUDE for 2100 - 2400 UT. 56-58 I3 Ap or PLANETARY 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 the Zurich num- ber through December 31, 1980, and the International Brus- sels number thereafter. 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 to the -22 Watts/ meter sq/hertz. Observations began on February 14, 1947. From that date through December 31, 1973, the fluxes given here don't reflect the revisions Ottawa made in 1966. NOTE: If a solar radio burst is in progress during the observation the pre-noon or afternoon value is used (as indicated by a flux qualifier value of 1 in column 71. 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; and "3" indicates no observation. -------------------------------------------------------------------------------