K Indices of Magnetic Activity Relative to an assumed Quiet-day for each 3-Hour PeriodBack to Collection NOAA/NESDIS/NGDC/STP/Indices
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K Indices of Magnetic Activity Relative to an assumed Quiet-day for each 3-Hour Period
The National Geophysical Data Center receives the K indices on a current basis from approximately 85 observatories. The K index is a quasi-logarithmic local index of the 3-hourly range in magnetic activity relative to an assumed quiet-day curve for the recording site. First introduced by J. Bartels in 1938, it consists of a single digit 0 through 9 for each 3-hourly interval. The K indices are received on a monthly basis from the various observatories and are available from 1938 to present. The National Geophysical Data Center also receives KP indices from the Institute for Geophysik in Gottingen, Germany on a monthly basis. The KP index is a planetary index based on the K index from 12 or 13 selected stations and has been derived routinely from 1932.

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K Indices
FTP site of K Indices for download
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Justin Mabie
DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce
303 497-6135
8:00 - 5:00 Mountain
No cost for download

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While every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA cannot assume liability for any damages caused by any errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.

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