Magnetometer Data

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By downloading data from SuperMAG you agree to follow the Rules of the Road

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.

[green]Selected Station [red]Available Station (Data Present) [grey]Available Station (No Data Present)

Station Information

SuperMAG magnetometer data is provided at the station level by the SuperMAG collaborators and station coverage of the data set varies with time (see Figure 1).

Figure 1. Station Coverage in the SuperMAG Data Set as of August 2017

Station name, geographic location and IAGA code can be downloaded as an ASCII file. The file includes a description of variables and other information.

When using this file please acknowledge the SuperMAG collaboration by including the reference below.

Some of the three letter codes are not official IAGA codes but are designated by SuperMAG.

Bxx indicate BAS operated stations
Txx indicate THEMIS project stations
Mxx indicate McMac operated stations
Cxx indicate CARISMA operated stations
Exx indicate ENIGMA operated stations
Pxx indicate EMMA operated stations
Sxx indicate SAMNET operated stations
Axx indicate AMBER operated stations
Gxx indicate MAGDAS operated stations

References:

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

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

Stations

Coordinate System

Global studies require all data to be rotated into a common known coordinate system. Data provided to SuperMAG from the collaborators are typically in either:

  • Geographic coordinates (north (X), east (Y), vertical down (Z))
  • Geographic coordinates (horizontal intensity (H), declination (D) and vertical down (Z))
  • Geomagnetic coordinates> (magnetic north (H), magnetic east (D) and vertical down (Z))
with or without baselines subtracted. During intitial setup the sensor axes are oriented in either the geographic or local magnetic coordinate system. The Earth main field, however, is constantly changing so the geomagnetic coordinate system is time dependent. The various uncertainties in mind SuperMAG decided to make no assumptions as to the initial setup of the magnetometer other than the Z-axis being vertical. Using the two horizontal components SuperMAG determines a slowly varying time dependent declination angle and subsequently rotates the horizontal components into a local magnetic coordinate system for which the magnetic east component (E) is minimized and the magnetic north component (N) is maximized. Note that geomagnetic coordinates are routinely labeled HDZ although the units of the D-component can be nT or an angle. Likewise, the D-component is often found to have a significant offset. As a consequence SuperMAG decided to denote the components:

B=(BN,BE,BZ)

where
  • N-direction is local magnetic north
  • E-direction is local magnetic east
  • Z-direction is vertically down

By definition the typical value (offset) of the E-component is zero. This reference system is independent of the actual orientation of the two horizontal magnetometer axes and the data can be rotated to any desired coordinate system using the appropriate IGRF model.

Baseline Determination

SuperMAG provides four options for the user:

  1. Subtract the daily variations and yearly trend (using Gjerloev, 2012)
  2. Subtract only the yearly trend (using Gjerloev, 2012)
  3. Do not subtract any baseline
  4. Subtract the start value from thee remaining of the interval.

SuperMAG thus provides 3 different solutions. The user should use the appropriate dataset for the study. As an example a study of the Sq current or the equatorial electrojet should not subtract the daily variations since this will remove part of this signal.

The purpose of determining the baseline is to perform a separation of sources. The measured field on the surface of the Earth is due to a list of sources:

Bmeasured = Bmain + BSq + BFAC + BRC + BEJ + BMP + ...

where the right side terms indicate the contribution due to: The Earth main field; the Sq current system; the field-aligned currents; the ring current; the auroral electrojets; and the magnetopause currents.

The focus of SuperMAG is ionosphere-magnetosphere research so perturbations produced by currents flowing in and between the ionosphere and the magnetosphere should be maintained while all other sources to the measured field should be removed. According to Ampere’s law it is impossible to determine a single unique current solution from the measured field. It is, however, possible to make a separation of sources if reasonable assumptions are made. For example, that the Earth main field is slowly varying compared to all other sources.

The question as to how the baseline should be determined is still under debate as evident from the stream of new papers being published (e.g. Mayaud, 1980; Menvielle et al., 1995; Takahashi et al., 2001; Janzhura and Troshichev, 2008). The fundamental problem is that there is no objective way to evaluate the quality of each technique. In validating any result or technique it is required that a set of ground-truth observations exists. Agreeing with another set of results does not provide an argument of validity, as both could be erroneous. This is particularly true for baseline determination as just about any data provider and as many scientists have developed their own technique.

As mentioned above the purpose of the baseline determination is fundamentally to perform a separation of sources. As there is no objective way to separate the sources neither is there a way to perform an objective evaluation. We therefore conclude that the user of the data must keep in mind the assumptions used in the baseline determination and draw conclusions accordingly.

The above discussion (see Gjerloev, 2012 for an extensive discussion) is why SuperMAG provides four options for the user.

Reference

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

Janzhura, A. S. and O. A. Troshichev, Determination of the running daily geomagnetic variation, J.Atmos.Solar-Terr.Phys. 70, 962-972, doi:10.1016/j.jastp.2007.11.004, 2008.

Mayaud, P. N., Derivation, meaning and use of geomagnetic indices, Geophys.Monographs,Ser., 22, 154, AGU, Washington D.C., 1980.

Menvielle, M., N. Papitashvili, L. Hakkinen, and C. Suckdorff, Computer production of K indices: Review and comparison of methods, Geophys.J.Int., 123, 866-886, doi:10.1111/j.1365-246X.1995.tb06895.x 1995.

Takahashi, K., B. toth, and J. V. Olson (2001), An automated procedure for near-real-time Kp estimates, J. Geophys. Res., 106, 21,017-21,032, doi:10.1029/2000JA000218.

Magnetometer Line Plots

Plot and download time series data from magnetometer stations.

To plot and download the data use you must:

  1. Select the time range of interest
  2. Select the stations of interest:
    This can be done three ways:
    • Use the various Lat/Lon options below
    • Select individual stations using the station checklist
    • Use the select options on the map
  3. Select various plotting options:
    The following plot options are available:
    • U/L envelope (upper/lower envelope of N-component for selected stations
    • Subtract start (subtract the value at the start of the time interval for each component)
    • Do Not Remove Daily Baseline (remove yearly trend but includes daily variations)
    • Do Not Remove Any Baseline (validated and rotated data without any baseline removal)
    • IMF GSM and IMF GSE - Propagated IMF in GSM/GSE coordinates
  4. To download the data and/or plots you must login.

Information about SuperMAG data