When this NWRA web site was initiated in 1997, the only real-time values available for the widely-used Kp index of global geomagnetic activity were estimates based on limited sets of magnetometer data or estimates derived from observations of the equatorward edge of the auroral oval precipitation from DMSP SSJ4 and TIROS SEM sensors. These were referred to as either preliminary or effective (the SSJ4 and TIROS estimate) Kp values.

Currently, this site uses IAGA "quicklook" estimates of Kp from the GeoForchungsZentrum Helmholtz Centre Potsdam. References for these data are given below.

References and Citations:

Matzka, J., Stolle, C., Yamazaki, Y., Bronkalla, O. and Morschhauser, A., 2021. The geomagnetic Kp index and derived indices of geomagnetic activity. Space Weather, https://doi.org/10.1029/2020SW002641.

Matzka, J., Bronkalla, O., Tornow, K., Elger, K. and Stolle, C., 2021. Geomagnetic Kp index. V. 1.0. https://doi.org/10.5880/Kp.0001.