Note: This plot is updated every hour.

The parameter shown in this plot is the effective Q index derived from observations of the precipitating electrons which are the source of high-latitude aurora. The measurements are from an electron spectrometer on the USAF Defense Meteorological Satellite Program (DMSP) satellites (part of the SSJ/4 sensor package). An algorithm developed by the Battlespace Environment Division of the USAF Research Laboratory is used by the USAF Weather Agency Space Weather Operation Center (AFWA/XOGX, located at Offutt AFB, NE) to determine the equatorward boundary of auroral electron precipitation from which the effective Q index is derived.

The heavy line on this plot is an esimtate of Qe derived from the IAGA Kp quicklook values. The equation used to estimate Qe from Kp is [ Qe = 2.0*Kp - 0.35 ]. This is reported to be the equation used by AFWA/XOGX to calculate Qe from the Kp estimates they make from the SSJ4 boundary locations.

Note: This plot is updated every hour. All data made available by the USAF is plotted.

The parameter shown in this plot is a boundary index, often referred to as an "effective" Kp, derived from the DMSP SSJ/4 boundary analyses described above. This index is calculated using an algorithm derived from plots posted on the AFRL DMSP SSJ4 website, and is given by Kpe = 0.41*(69.0 - BndLat), where BndLat is the auroral boundary latitude at midnight as derived from the SSJ4 observations. The original source of this algorithm is unknown.

The heavy lines plotted on this figure are the IAGA Kp quicklook values.

NOTE: The SSJ4-derived boundary index is referred to in the literature, and by the USAF organizations that used the index operationally, as an effective Kp index, or Kpe. The index can be used as a surrogate for Kp in models that set the location of the auroral electron precipitation using the model of this boundary described in the cited paper. While the index can also be used as a Kp surrogate in other models that require a Kp input, great care should be taken in doing this.

The DMSP SSJ/4 analyses used in these plots were obtained from the US Air Force Weather Agency Space Weather Operation Center (AFWA/XOGX) at Offutt Air Force Base NE.