Magnetic Indices

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Rules of the Road

SuperMAG is made possible by the generous contribution by a long list of collaborators. To ensure their continued operation the user must follow the below rules-of-the-road. Data, plots or derived data products are provided under the limitations of "fair use" and cannot be redistributed. Contact the individual instrument PI and the SuperMAG PI for requests that are in conflict with these restrictions.

The user is requested to acknowledge individual collaborators and SuperMAG when original data, derived data, movies, or data products are used in publications and/or presentations.

In all cases:

  1. Include acknowledgement as listed on the SuperMAG website.
  2. Include references to a technical papers for stations used.
  3. Include SuperMAG reference: Gjerloev, J. W. (2012), The SuperMAG data processing technique, J. Geophys. Res., 117, A09213, doi:10.1029/2012JA017683.

In cases that a few stations play a key role and their data are central to the scientific conclusion of the paper:

  1. Offer of co-authorship to the PI (or PIs) of those stations.

Acknowledgment:

For the ground magnetometer data we gratefully acknowledge: Intermagnet; USGS, Jeffrey J. Love; CARISMA, PI Ian Mann; CANMOS; The S-RAMP Database, PI K. Yumoto and Dr. K. Shiokawa; The SPIDR database; AARI, PI Oleg Troshichev; The MACCS program, PI M. Engebretson, Geomagnetism Unit of the Geological Survey of Canada; GIMA; MEASURE, UCLA IGPP and Florida Institute of Technology; SAMBA, PI Eftyhia Zesta; 210 Chain, PI K. Yumoto; SAMNET, PI Farideh Honary; The institutes who maintain the IMAGE magnetometer array, PI Eija Tanskanen; PENGUIN; AUTUMN, PI Martin Connors; DTU Space, PI Dr. Rico Behlke; South Pole and McMurdo Magnetometer, PI's Louis J. Lanzarotti and Alan T. Weatherwax; ICESTAR; RAPIDMAG; PENGUIn; British Artarctic Survey; McMac, PI Dr. Peter Chi; BGS, PI Dr. Susan Macmillan; Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN); GFZ, PI Dr. Juergen Matzka; MFGI, PI B. Heilig; IGFPAS, PI J. Reda; University of L’Aquila, PI M. Vellante; BCMT, V. Lesur and A. Chambodut; Data obtained in cooperation with Geoscience Australia, PI Marina Costelloe; SuperMAG, PI Jesper W. Gjerloev.

References (alphabetically):

EMMA:
Lichtenberger J., M. Clilverd, B. Heilig, M. Vellante, J. Manninen, C. Rodger, A. Collier, A. Jørgensen, J. Reda, R. Holzworth, and R. Friedel (2013), The plasmasphere during a space weather event: first results from the PLASMON project, J. Space Weather Space Clim., 3, A23 (www.swsc-journal.org/articles/swsc/pdf/2013/01/swsc120062.pdf).

IMAGE Chain:
Tanskanen, E.I. (2009), A comprehensive high-throughput analysis of substorms observed by IMAGE magnetometer network: Years 1993-2003 examined, 114, A05204, doi:10.1029/2008JA013682.

MACCS:
Engebretson, M. J., W. J. Hughes, J. L. Alford, E. Zesta, L. J. Cahill, Jr., R. L. Arnoldy, and G. D. Reeves (1995), Magnetometer array for cusp and cleft studies observations of the spatial extent of broadband ULF magnetic pulsations at cusp/cleft latitudes , J. Geophys. Res., 100, 19371-19386, doi:10.1029/95JA00768.

McMAC Chain:
Chi, P. J., M. J. Engebretson, M. B. Moldwin, C. T. Russell, I. R. Mann, M. R. Hairston, M. Reno, J. Goldstein, L. I. Winkler, J. L. Cruz-Abeyro, D.-H. Lee, K.Yumoto, R. Dalrymple, B. Chen, and J. P. Gibson (2013), Sounding of the plasmasphere by Mid-continent MAgnetoseismic Chain magnetometers, J. Geophys. Res. Space Physics, 118, doi:10.1002/jgra.50274.

MAGDAS / 210 Chain:
Yumoto, K,. and the CPMN Group (2001), Characteristics of Pi 2 magnetic pulsations observed at the CPMN stations: A review of the STEP results, Earth Planets Space, 53, 981-992.

SuperMAG:
Gjerloev, J. W. (2012), The SuperMAG data processing technique, J. Geophys. Res., 117 , A09213, doi:10.1029/2012JA017683.

Magnetic Indices

Magnetic indices are derived from the magnetometer data provided by the SuperMAG collaborators. These indices are not official indices and are not authorized by IAGA. The official indices can be found at World Data Center for Geomagnetism, Kyoto

If you use the indices in publications and/or presentations please clearly indicate that these are SuperMAG derived indices.

Caveats

  1. Despite comprehensive and time consuming data correction and validation SuperMAG does not guarantee the quality of the data from the individual station and thus does not guarantee the quality of the indices either. The user is encouraged to validate the data before using them in publications.
  2. Indices are revised as new stations are added to the data holdings.
  3. Finally, the indices are based on the SuperMAG version of the data and thus have undergone error correction, temporal resampling, rotation, and the baseline has been subtracted. The data used are thus not equivalent to the original data that can be obtained from the collaborators.

Method of derivation: SMU and SML indices (based on AU and AL indices)

  1. Based on all available ground magnetometer stations at geomagnetic latitudes between +40º and +80º degrees;
  2. From all available stations we use the N component with the baseline removed;
  3. SMU is defined as the maximum value at each moment of the N component;
  4. SML is defined as the minimum value at each moment of the N component.
  5. SME = SMU - SML

Typically, these indices are derived from approximately 110 stations. For full description see Newell and Gjerloev [2011a,b].

The sunlit and darkness indices are derived in the same way. The difference is that the darkness indices (SMUD and SMLD) are derived from stations located under the dark ionosphere. Likewise, the sunlit indices (SMUS and SMLS) are derived from stations located under the sunlit ionosphere. The terminator is defined at an altitude of 200 km for solar zenith angles of 104°. In agreement with the above definition (5) we finally get:

  1. SMES = SMUS - SMLS
    SMED = SMUD - SMLD

For full description see Gjerloev et al. [2009].

Method of derivation: SMR indices (SMR based on SYMH)

  1. Based on all available ground magnetometer stations at geomagnetic latitudes (mlat) between -50 and +50 degrees;
  2. From all available stations we use the N component with the baseline removed;
  3. The magnetic latitude is used for a correction: Ncorr=N/cos(mlat);
  4. Four equally sized local time sectors are defined with centers at 00, 06, 12, 18 MLT;
  5. SMR-00 is defined as the average at each moment of Ncorr for all available stations within the local time sector (21 MLT to 03 MLT). Likewise for the other sectors;
  6. SMR is defined as: SMR = (SMR-00 + SMR-06 + SMR-12 + SMR-18)/4

Typically, the SMR is derived from approximately 100 stations. For full description see Newell and Gjerloev [2012].

References

Davis, T. N., and M. Sugiura (1966), Auroral electrojet activity index AE and its universal time variations, J.Geophys.Res., 71, 785, doi:10.1029/JZ071i003p00785.

Gjerloev, J. W. (2009), A Global Ground-Based Magnetometer Initiative, EOS, 90, 230-231, doi:10.1029/2009EO270002.

Gjerloev, J. W., R. A. Hoffman, S. Ohtani, J. Weygand, and R. Barnes, Response of the Auroral Electrojet Indices to Abrupt Southward IMF Turnings (2010), Annales Geophysicae, 28, 1167-1182. (www.ann-geophys.net/28/1167/2010/angeo-28-1167-2010.pdf)

Gjerloev, J. W. (2012), The SuperMAG data processing technique, J. Geophys. Res., 117, doi:10.1029/2012JA017683.

Newell, P. T., and J. W. Gjerloev (2011), Evaluation of SuperMAG auroral electrojet indices as indicators of substorms and auroral power, J. Geophys. Res., 116, A12211, doi:10.1029/2011JA016779.

Newell, P. T., and J. W. Gjerloev (2011), Substorm and magnetosphere characteristic scales inferred from the SuperMAG auroral electrojet indices, J. Geophys. Res., 116, A12232, doi:10.1029/2011JA016936.

Newell, P. T. and J. W. Gjerloev (2012), SuperMAG-Based Partial Ring Current Indices, J. Geophys. Res., 117, doi:10.1029/2012JA017586.

Sugiura, M. (1964), Hourly values of equatorial Dst for the IGY, Ann. Int. Geophys., 35, 9, Pergamon Press, Oxford.

Magnetic indices are derived from the magnetometer data provided by the SuperMAG collaborators. These indices are not official indices and are not authorized by IAGA. The official indices can be found at World Data Center for Geomagnetism, Kyoto.

If you use the indices in publications and/or presentations please clearly indicate that these are SuperMAG derived indices and are not the official indices.

Available indices

SMU
Maximum eastward auroral electrojets strength.
Upper envelope of N-component for stations between 40° and 80° magnetic north.
SML
Maximum westward auroral electrojets strength.
Lower envelope of N-component for stations between 40° and 80° magnetic north.
SME
SMU-SML
SMR
Symmetric ring current index.
SMR-LT
Partial ring current indices, SMR-00, SMR-06, SMR-12, SMR-18.
Ring current indices partitioned by MLT (Magnetic local time).

Magnetic longitude and latitude of the stations are given in AACGM coordinates.

Full description

Solar Wind Data

Solar Wind data has been propagated to the front of the magnetosphere (courtesy Dr. James Weygand) using the pseudo-minimum variance technique of Dan Weimer et al. [2003; 2004].

Full description