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AE, AU, AL, AО Indices of Geomagnetic Activity
AE, AU, AL, AО indices of geomagnetic activity characterize the magnetic disturbance in the auroral zone
due to the increase in currents in the ionosphere along the boundary of the auroral oval (the eastern and western currents
of the polar electrojet).
The method of calculating the AU, AL, AE, AO indices is based on determining the magnitude of the deviation
of the horizontal H component of the geomagnetic field from a quiet level - the average monthly value H
calculated according to five international quiet days. To calculate AU, AL, AE, AO indices, the geomagnetic data
of 12 observatories located at auroral or subauroral latitudes and uniformly distributed over the longitude are used:
Abisko, Dixon Island, Cape Chelyuskin, Tixie Bay, Pebek, Barrow, College, Yellowknife, Fort Churchill, Sanikiluaq, Narssarssuaq, and Leirvogur.
AU index (auroral upper) corresponds to the maximum positive deviation of H component of the magnetic
field from the average quiet level for all observatories of the auroral zone.
AL index (auroral low) corresponds to the maximum negative deviation of H component of the magnetic
field from the average quiet level for all observatories of the auroral zone.
AЕ index was proposed by Davis and Sugiura [1966]. It is defined as the sum of the absolute values of the
AU and AL indices, i.e. the total
magnitude of the magnetic fluctuations in the H component of the geomagnetic field. The index AЕ characterizes
magnetic perturbation in the zone as a whole, irrespective of the place of appearance of the perturbation.
The value (AU+AL)/2 was defined as the AO index and it geometrically represents the moving midpoint
between AU and AL values at any given time.
The values of the AE, AU, AL, AO indices are calculated and made available by the
World Data Center for Geomagnetism, Kyoto
from data collected at magnetic observatories.
Hourly values of the AE, AU, AL, AО indices from 1957 to the present in
WDC format
(until 1966 only AE index; data for 1976 and 1977 are absent).
Hourly values of the AE, AU, AL, AО indices from 1957 to the present in
IAGA2002 format
(until 1966 only AE index; data for 1976 and 1977 are absent).
Minute values of the AE, AU, AL, AО indices from 1974 г. to the present in
WDC format
(data for VII.1988-II.1989 and IV-XII.1989 are absent).
Minute values of the AE, AU, AL, AО indices from 1974 г. to the present in
IAGA2002 format
(data for VII.1988-II.1989 and IV-XII.1989 are absent).
Citation: World Data Center for Geomagnetism, Kyoto, Nose M., Iyemori T., Sugiura M. and Kamei T. (2015) -
Geomagnetic АЕ index, doi:10.17593/15031-54800.
WDC for STP, Moscow is grateful to the ISGI Collaborating Institute
World Data Center for Geomagnetism, Kyoto, the
INTERMAGNET network and
International Service of Geomagnetic Indices – ISGI (isgi.unistra.fr).
Using the data, please be sure to indicate the above organizations according to the following
template.
Reference: Davis, T. N., and M. Sugiura (1966) - Auroral electroject activity index AE and its universal time variations,
J. Geophys. Res., 71, 785-801, doi:10.1029/JZ071i003p00785.
How to Cite Datasets:
Ball, A. and M. Duke [2011], How to cite datasets and link to publications, DCC How-to Guides, Edinburgh: Digital Curation Centre.
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