@article{364c4996c0ba46ca97416d346cf4ce00,

title = "Nighttime Magnetic Perturbation Events Observed in Arctic Canada: 1. Survey and Statistical Analysis",

abstract = "The rapid changes of magnetic fields associated with large, isolated magnetic perturbations with amplitudes |ΔB| of hundreds of nanotesla and 5- to 10-min periods can induce bursts of geomagnetically induced currents that can harm technological systems. This paper presents statistical summaries of the characteristics of nightside magnetic perturbation events observed in Eastern Arctic Canada from 2014 through 2017 using data from stations that are part of four magnetometer arrays: MACCS, AUTUMNX, CANMOS, and CARISMA, covering a range of magnetic latitudes from 68 to 78°. Most but not all of the magnetic perturbation events were associated with substorms: roughly two thirds occurred between 5 and 30 min after onset. The association of intense nighttime magnetic perturbation events with magnetic storms was significantly reduced at latitudes above 73°, presumably above the nominal auroral oval. A superposed epoch study of 21 strong events at Cape Dorset showed that the largest |dB/dt| values appeared within an ~275-km radius that was associated with a region of shear between upward and downward field-aligned currents. The statistical distributions of impulse amplitudes of both |ΔB| and |dB/dt| fit well the log-normal distribution at all stations. The |ΔB| distributions are similar over the magnetic latitude range studied, but the kurtosis and skewness of the |dB/dt| distributions show a slight increase with latitude. Knowledge of the statistical characteristics of these events has enabled us to estimate the occurrence probability of extreme impulsive disturbances using the approximation of a log-normal distribution.",

keywords = "geomagnetically induced currents, magnetic impulse events, magnetic storms, substorms",

author = "Engebretson, {M. J.} and Pilipenko, {V. A.} and Ahmed, {L. Y.} and Posch, {J. L.} and Steinmetz, {E. S.} and Moldwin, {M. B.} and Connors, {M. G.} and Weygand, {J. M.} and Mann, {I. R.} and Boteler, {D. H.} and Russell, {C. T.} and Vorobev, {A. V.}",

note = "Funding Information: We thank S. Ohtani for helpful comments. This work was supported by NSF grant AGS-1651263 to Augsburg University (M. J. E., V. A. P., L. Y. A., J. L. P., and E. S. S.), NSF grant AGS-1654044 to the University of Michigan (M. B. M.), NASA grants 80NSSC18K0570 and 80NSSC18K1220 and NASA contract NAS5-02099 to UCLA (J. M. W.), and grant 16-17-00121 from the Russian Science Foundation (A. V. V.). I. R. M. was supported by the Natural Sciences and Engineering Research Council of Canada. We thank D. K. Milling and the rest of the CARISMA team for data. CARISMA is operated by the University of Alberta, funded by the Canadian Space Agency. MACCS magnetometer data are available at http://space.augsburg.edu/maccs/requestdatafile.jsp; AUTUMNX data are available at http://autumn.athabascau.ca/autumnxquery2.php?year=2015&mon=01&day=01; CANMOS data, provided by the Geological Survey of Canada, are available at http://geomag.nrcan.gc.ca/data-donnee/sd-en.php; and CARISMA data are available at http://www.carisma.ca/carisma-data-repository. The SME index is available from SuperMAG (http://supermag.jhuapl.edu/indices/; PI J. Gjerloev), derived from magnetometer data from Intermagnet; USGS, J. J. Love; CARISMA, PI I. Mann; CANMOS, Geomagnetism Unit of the Geological Survey of Canada; The S-RAMP Database, PI K. Yumoto and K. Shiokawa; The SPIDR database; AARI, PI O. Troshichev; The MACCS program, PI M. Engebretson; GIMA; MEASURE, UCLA IGPP and Florida Institute of Technology; 210 Chain, PI K. Yumoto; SAMNET, PI F. Honary; the institutes who maintain the IMAGE magnetometer array, PI E. Tanskanen; PENGUIN; AUTUMN, PI M. Connors; DTU Space, PI R. Behlke; South Pole and McMurdo Magnetometer, PI's L. J. Lanzerotti and A. T. Weatherwax; ICESTAR; RAPIDMAG; PENGUIn; British Antarctic Survey; McMAC, PI P. Chi; BGS, PI S. Macmillan; Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN); GFZ, PI Juergen Matzka; MFGI, PI B. Heilig; IGFPAS, PI J. Reda; University of L'Aquila, PI M. Vellante. Publisher Copyright: {\textcopyright}2019. American Geophysical Union. All Rights Reserved.",

year = "2019",

month = sep,

day = "1",

doi = "10.1029/2019JA026794",

language = "English",

volume = "124",

pages = "7442--7458",

number = "9",

}