The Geomagnetic Indices Bulletin is a one page sheet containing the magnetic indices Kp, Ap, Cp, An, As, Am and the provisional aa indices. The bulletin is published monthly.

Report on the status of world wide geomagnetic observatories

Geomagnetic 10 second data provides high temporal resolution of geomagnetic variations

1 minute and hourly values reported as definitive from Intermagnet observatories.

Bibliography of Historical Geomagnetic Main Field Surveys as reference source

The Deep Space Climate ObserVatoRy (DSCOVR) satellite is a NOAA operated asset at the first Lagrange (L1) point. The primary space weather instrument is the PlasMag suite. PlasMag includes a fluxgate magnetometer (MAG) that measures the local magnetic field, and a Faraday Cup (FC) that measures the solar wind bulk properties (wind speed, density and temperature). The PlasMag solar wind data are essential inputs for the forecasts and nowcasts provided to SWPC customers. The PlasMag data are also available to scientists for sensor cal/val and for research purposes. DSCOVR was launched on Feb. 11, 2015, so all data present in the Archive from earlier dates are data used for ground testing, and do not represent the space environment. DSCOVR became operational on July 27, 2016. End Of Life (EOL) is anticipated to be December 2019. NCEI plans to receive data until EOL, and will continue to archive the data in accordance with Data Center policies.

Several regions are represented in this unique collection of earth surface measurements of magnetic field parameters and their related anomalies. The DNAG Magnetics "Super grid" of Magnetic Anomaly Map of North America was created from the four "Original" DNAG Magnetic data sets distributed by The Committee for the Magnetic Anomaly Map of North America, 1987. This development of a super grid involved an extensive task of matching original quadrant information and eliminating overlap. The resulting grid, with x and y step intervals of 2.0 kilometers yields a grid with dimensions (4451 x 4273) containing 19,019,123 values. This process can be thought of as "stitching the grids." The data in this grid are in a Spherical Transverse Mercator projection, the kilometer coordinates of which can be recovered from the indices of a grid point. The Ministry of Geology of the USSR published a mosaic series of 18 maps in 1974, at a scale of 1:2,500,000 showing the residual magnetic intensity over the land mass of the USSR. Much of the source material originated from data collected between 1949-1962, during which time the entire territory of the USSR was surveyed using aerial magnetic survey techniques. These surveys wereadjusted based on many methods including secular variation linked to magnetic observatories. Anomalies were computed with reference to a normal field map for 1964-65 constructed from equally accurate total field measurements along control network strips. Digitization was accomplished in 1982 by the U.S. Naval Oceanographic Office. The "BRIGGS cubic spline" method was used to compute grid values. A one-minute grid was created by properly matching the boundaries of the digitized sub-sections. The units of the original map aremilli-Oersteds and the units of the resulting digital grid are milli-Oersted/100. Corrections to the digital contour file were made by Conoco Inc.in 1993. New Grid files at 2.5 Km and 5.0 Km spacing were created and re-archived by NGDC. These data are available on CD-ROM. World Data Center-A (WDC-A) for Solid Earth Geophysics presently holds Grid data from many U.S. and other regions. These data were contributed by: USGS, MINN G.S. and other Worldwide organizations. Grid intervals vary but are as fine as 213.36m for the NGS Super Grid of the state of Minnesota. Other grids were recreated indigital form from previously published maps and charts. The bulk of these grid data files were contributed to NGDC after 1985. A detailed list of the specific regions is available upon request.

Storm Sudden Commencements (ssc) 1868 to present: STORM1 and STORM2 Lists: (Some text here is taken from the International Association of Geomagnetism and Aeronomy (IAGA) Bulletin 39) 1868-1967 data (STORM1.SSC) are from IAGA Bulletin 33. These data are based on 3 observatories. Only one of them was at low latitude; the other two, with an invariant magnetic latitude of 50 degrees, were strongly sensitive to the auroral effect. 1968-1975 data (STORM2.SSC) are from IAGA Bulletin 39. These data are much more reliable. The monthly reports from all observatories guarantee that very few events are omitted. With the examination of five low-latitude records, the changes of rhythm could be evaluated much better, and events were kept of rejected on a more rational basis. However, it is probable that, for statistical use, both lists will be relatively homogeneous. Indeed, Alibag was the low-latitude observatory of the 100-year list and belongs, in the 1968-1975 list, to the group form which the amplitudes are close to the average of five observatories. 1976-1982 data are from IAGA Bulletin 32 series. These data are reduced in the same manner as the 1968-1975 data. 1983-present data are from the monthly ISGI Bulletins (DeBilt, Netherlands - 1983-1987 data; Institut de Physique du Globe, Paris, France - 1988-present data.

The NOAA National Centers for Environmental Information (formerly 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 NOAA National Centers for Environmental Information (formerly 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.

This file is comprised of absolute mean hourly values of the geomagnetic components D, H and Z or X, Y and Z. These values, on magnetic tape, are available from approximately 220 of the 400 worldwide observatories which have ever operated. Most of the values were hand-scaled from the analog recordings (magnetograms) and were added to the file via punched cards. From some observations, for more recent years, there are means of values recorded directly on magnetic tape from digital magnetometers at various sample rates, for example, each minute. The accuracy of these data varies but is generally good, particularly for the more recent years. Approximately 60 observation-years of these data are added to the files each year.