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Main Page   >   Geomagnetic Variations   >   Indices of geomagnetic activity   >    K and С indices 

K and С Indices of Geomagnetic Activity

K index is a quasi-logarithmic three-hour index characterizing the change in geomagnetic activity at a specific observatory in the three-hour time intervals, starting at 00 h of universal time (UT), and is expressed in balls. K index takes values from 0 (quiet magnetic field) to 9. The value of K = 9 corresponds to a very strong geomagnetic disturbance. Taking into account that the amplitude of the geomagnetic disturbance depends on the latitude of the place of observation, the value of K = 9 corresponds to a perturbation greater than 2500 γ in the auroral zone and greater than 300 γ at low latitudes (excluding the equator). For all other observatories located in the polar cap and mid-latitudes, a value of K = 9 corresponds to perturbations of less than 2500 γ, but greater than 300 γ.
Each observatory, publishing data on the K index, necessarily indicates a lower limit for K = 9.

С index - the simplest index of geomagnetic activity. It characterizes the geomagnetic field perturbation during the day and has a three-point scale (0, 1, 2). At each observatory, the magnetologist "by eye" estimates the perturbation of the geomagnetic field for a day. The quietest records of the geomagnetic field are estimated by zero, the most turbulent - the number 2. This characteristic is often subjective.

Catalog of the availability of data about the values of K and С indices

К index according to the data of 44 observatories of Russia and the CIS countries since 1957.
      Data Format.

К and С indices according to the data of 40 observatories of Russia and the CIS countries and stations "North Pole".
Tables converted from paper to electronic form - pdf format.
Data for С index for the period 1957-1971.
Data for К index since 1957.
Some of the tables contain geomagnetic storm data.
      The data file name includes the three-letter code of the observatory and the year.
      If there are data not for the whole year, after the year the months are indicated.
      If the tables contain data on geomagnetic storms, then the letter combination "st".

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