Indices

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Geomagnetic indices and solar wind parameters

A historical database, containing a number of geomagnetic indices, solar wind parameters and some derived parameters has been compiled for the period 1950 -- present. The next table describes the available parameters and their sources:

**Geomagnetic indices and solar wind parameters**
Index	Resolution [Hours]	Units	Comments
A_p: Planetary 3-hour equivalent amplitude	3	2 nT	01-01-1949--last month: downloaded from NOAA ftp site
Planetary daily equivalent amplitude	24	2 nT	01-01-1949--last month: downloaded from NOAA ftp site
A_p15	24	2 nT	01-01-1949--last month: Calculated from daily averages: arithmetic mean
K_p: Planetary 3-hour range index	3	-	01-01-1949--last month: downloaded from NOAA ftp site
Daily sum of the eight K_p indices	24	-	01-01-1949--last month: downloaded from NOAA ftp site
Linear filter on the daily sum K_p values	24	-	01-01-1949--last month: Calculated [Baker et al. (1990)¹]
Geomagnetic aa index: antipodal activity	3	nT	01-01-1949--31-12-1996: Definitive downloaded from NOAA ftp site 01-01-1997--31-12-2002: Provisional downloaded from World Data Centre for Solar-Terrestrial Physics, Chilton
Daily averaged aa index	24	nT	01-01-1949--31-12-1996: Definitive downloaded from NOAA ftp site 01-01-1997--31-12-2002: Provisional calculated from hourly values
Geomagnetic am index	3	nT	01-01-1959--31-12-1993: Definitive downloaded from ISGI Web server 01-01-1994--31-12-2002: Provisional downloaded from ISGI Web server
Daily averaged am index	24	nT	01-01-1959--31-12-2002: calculated from three-hourly values
F_10.7: Ottawa 10.7 cm solar radio flux adjusted to 1 AU	24	10^-22 J s^-1 m^-2 Hz^-1	01-01-1949--last month: downloaded from NOAA ftp site
Three monthly averaged F_10.7 flux	24	10^-22 J s^-1 m^-2 Hz^-1	01-01-1949--last month: Calculated from daily values
D_st: Disturbance storm time index	1	nT	01-Jan-1957--31-Dec-1998: Definitive downloaded from NOAA ftp site 01-Jan-1999--31-Dec-2008: Definitive downloaded from World Data Center for Geomagnetism, Kyoto 01-Jan-2009--31-Dec-2011: Provisional downloaded from World Data Center for Geomagnetism, Kyoto 01-Jan-2012--last month: Quick Look downloaded from World Data Center for Geomagnetism, Kyoto
Daily averaged D_st index	24	nT	01-Jan-1957--31-Dec-1998: Definitive downloaded from NOAA ftp site 01-Jan-1999--31-Dec-2002: Definitive calculated from hourly values 01-Jan-2003--30-Jun-2004: Provisional calculated from hourly values 01-Jul-2004--last month: Quick look calculated from hourly values
AE: Auroral Electrojet	1	nT	01-Jul-1957--31-Dec-1975: Definitive downloaded from NOAA ftp site 01-Jan-1978--30-Jun-1988: Definitive downloaded from NOAA ftp site 01-Mar-1989--31-Mar-1989: Provisional downloaded from World Data Centre for Solar-Terrestrial Physics, Chilton 01-Jan-1990--31-Dec-1991: Provisional downloaded from World Data Centre for Solar-Terrestrial Physics, Chilton 01-Jan-1992--31-Jun-2012: Provisional downloaded from World Data Center for Geomagnetism, Kyoto 01-Jan-1993--31-Dec-1994: Provisional downloaded from World Data Centre for Solar-Terrestrial Physics, Chilton 01-Jan-1997--31-Dec-2000: Quick look downloaded from World Data Centre for Solar-Terrestrial Physics, Chilton
Daily averaged auroral electrojet index	24	nT	01-Jul-1957--31-Dec-1975: Definitive downloaded from NOAA ftp site 01-Jan-1978--30-Jun-1988: Definitive downloaded from NOAA ftp site 01-Mar-1989--31-Mar-1989: Provisional calculated from hourly values 01-Jan-1990--31-Dec-1994: Provisional calculated from hourly values 01-Jan-1997--31-Dec-2000: Quick look calculated from hourly values
Linear filter on AE values	24	nT	Calculated from daily averages [Baker et al. (1990)¹]
AL: Amplitude lower	1	nT	01-Jan-1966--31-Dec-1975: Definitive downloaded from NOAA ftp site 01-Jan-1978--30-Jun-1988: Definitive downloaded from NOAA ftp site 01-Mar-1989--31-Mar-1989: Provisional downloaded from World Data Centre for Solar-Terrestrial Physics, Chilton 01-Jan-1990--31-Dec-1991: Provisional downloaded from World Data Centre for Solar-Terrestrial Physics, Chilton 01-Jan-1992--31-Jun-2012: Provisional downloaded from World Data Center for Geomagnetism, Kyoto 01-Jan-1993--31-Dec-1994: Provisional downloaded from World Data Centre for Solar-Terrestrial Physics, Chilton 01-Jan-1997--31-Dec-2000: Quick look downloaded from World Data Centre for Solar-Terrestrial Physics, Chilton
Daily averaged AL index	24	nT	01-Jan-1966--31-Dec-1975: Definitive downloaded from NOAA ftp site 01-Jan-1978--30-Jun-1988: Definitive downloaded from NOAA ftp site 01-Mar-1989--31-Mar-1989: Provisional calculated from hourly values 01-Jan-1990--31-Dec-1994: Provisional calculated from hourly values 01-Jan-1997--31-Dec-2000: Quick look calculated from hourly values
AU: Amplitude upper	1	nT	01-Jan-1966--31-Dec-1975: Definitive downloaded from NOAA ftp site 01-Jan-1978--30-Jun-1988: Definitive downloaded from NOAA ftp site 01-Mar-1989--31-Mar-1989: Provisional downloaded from World Data Centre for Solar-Terrestrial Physics, Chilton 01-Jan-1990--31-Dec-1991: Provisional downloaded from World Data Centre for Solar-Terrestrial Physics, Chilton 01-Jan-1992--31-Jun-2012: Provisional downloaded from World Data Center for Geomagnetism, Kyoto 01-Jan-1993--31-Dec-1994: Provisional downloaded from World Data Centre for Solar-Terrestrial Physics, Chilton 01-Jan-1997--31-Dec-2000: Quick look downloaded from World Data Centre for Solar-Terrestrial Physics, Chilton
Daily averaged AU index	24	nT	01-Jan-1966--31-Dec-1975: Definitive downloaded from NOAA ftp site 01-Jan-1978--30-Jun-1988: Definitive downloaded from NOAA ftp site 01-Mar-1989--31-Mar-1989: Provisional calculated from hourly values 01-Jan-1990--31-Dec-1994: Provisional calculated from hourly values 01-Jan-1997--31-Dec-2000: Quick look calculated from hourly values
AO: mean of AL and AU	1	nT	01-Jan-1966--31-Dec-1975: Definitive downloaded from NOAA ftp site 01-Jan-1978--30-Jun-1988: Definitive downloaded from NOAA ftp site 01-Mar-1989--31-Mar-1989: Provisional downloaded from World Data Centre for Solar-Terrestrial Physics, Chilton 01-Jan-1990--31-Dec-1991: Provisional downloaded from World Data Centre for Solar-Terrestrial Physics, Chilton 01-Jan-1992--31-Jun-2012: Provisional downloaded from World Data Center for Geomagnetism, Kyoto 01-Jan-1993--31-Dec-1994: Provisional downloaded from World Data Centre for Solar-Terrestrial Physics, Chilton 01-Jan-1997--31-Dec-2000: Quick look downloaded from World Data Centre for Solar-Terrestrial Physics, Chilton
Daily averaged AO index	24	nT	01-Jan-1966--31-Dec-1975: Definitive downloaded from NOAA ftp site 01-Jan-1978--30-Jun-1988: Definitive downloaded from NOAA ftp site 01-Mar-1989--31-Mar-1989: Provisional calculated from hourly values 01-Jan-1990--31-Dec-1994: Provisional calculated from hourly values 01-Jan-1997--31-Dec-2000: Quick look calculated from hourly values
15 minute averaged Polar Cap index (Thule)	0.25	-	01-Jan-1975--31-Dec-1998: Definitive downloaded from NOAA ftp site 01-Jan-1999--31-Dec-2002: Preliminary downloaded from NOAA ftp site
R_z: International Sunspot number	24	-	01-01-1949--last month: downloaded from NOAA ftp site
Solar wind ion density	1	cm^-3	02-Nov-1963--31-12-2002: Omniweb data downloaded from OmniWeb 15-Nov-1994--31-12-2002: WIND data downloaded from MIT² 23-Jan-1998--31-12-2002: ACE data downloaded from ACE Science Center³
Solar wind bulk speed	1	km s^-1	02-Nov-1963--31-12-2002: Omniweb data downloaded from OmniWeb 15-Nov-1994--31-12-2002: WIND data downloaded from MIT² 23-Jan-1998--31-12-2002: ACE data downloaded from ACE Science Center³
Daily averaged solar wind bulk speed	24	km s^-1	Calculated arithmetic mean of hourly values
Linear filter on solar wind bulk speed values	24	km s^-1	Calculated from daily averages [Baker et al. (1990)¹]
Plasma temperature	1	K	02-Nov-1963--31-12-2002: Omniweb data downloaded from OmniWeb 15-Nov-1994--31-12-2002: WIND data downloaded from MIT² 23-Jan-1998--31-12-2002: ACE data downloaded from ACE Science Center³
Plasma pressure	1	nPa	Calculated from solar wind velocity and density
Interplanetary magnetic field, x-component⁴	1	nT	02-Nov-1963--31-12-2002: Omniweb data downloaded from OmniWeb 23-Jan-1998--31-12-2002: ACE data downloaded from ACE Science Center³
Interplanetary magnetic field, y-component⁴	1	nT	02-Nov-1963--31-12-2002: Omniweb data downloaded from OmniWeb 23-Jan-1998--31-12-2002: ACE data downloaded from ACE Science Center³
Interplanetary magnetic field, z-component⁴	1	nT	02-Nov-1963--31-12-2002: Omniweb data downloaded from OmniWeb 23-Jan-1998--31-12-2002: ACE data downloaded from ACE Science Center³
Daily averaged z-component of IMF	24	nT	Calculated arithmetic mean of hourly values
Daily averaged negative z-component of IMF	24	nT	Calculated sum of hourly negative values/24
Epsilon	1	10¹⁸ erg s^-1	Calculated [Kan et al. (1980)]
Daily averaged epsilon	24	10¹⁸ erg s^-1	Calculated arithmetic mean of hourly values
Stand-off distance of the magnetopause	1	R_E	Calculated from balance of solar wind pressure and Earth magnetic field pressure
Daily averaged stand-off distance of the magnetopause	24	R_E	Calculated arithmetic mean of hourly values

Remarks:

The weights for the calculations of the linear filtered values were taken from Baker et al. (1990). Only the first 18 values were used, and the parameters were renormalized.
WIND data that is not included in the Omniweb set has been time shifted and renormalized as described in the document "On adding WIND/SWE Plasma Data To OMNI". The plasma temperature from the WIND data was calculated from the most probable thermal speed. For time stamps where both OMNI and WIND data are available, the WIND data has been used.
ACE data has been time shifted and renormalized in the same way as the WIND data. A new renormalization was performed for each year. Additionally, a renormalization was also applied to the solar wind speed and the magnetic field components. For time stamps where both ACE and OMNI or WIND data are available, the ACE data has been used.
The interplanetary magnetic field components are in the GSM coordinate system.

References:

Baker, D. N., R. L. McPherron, T. E. Cayton, and R. W. Klebesadel, Linear Prediction Filter Analysis of Relativistic Electron Properties at 6.6 R_E, JGR, 95, No. A9,, pp. 15133-15140, 1990.

Kan, J. R., L. C. Lee, and S.-I. Akasofu, The energy coupling function and the power generated by the solar wind-magnetosphere dynamo, Planet. Space Sci. Vol. 28, pp. 823-825, 1980.

King, J. H., and N. E. Papitashvili, "On adding WIND/SWE Plasma Data To OMNI", NSSDC, September 1999.

Last update: Mon, 12 Mar 2018