Auroral Electrojet (AE, AL, AO, AU) - A Global Measure of Auroral Zone Magnetic Activity
The AE index is derived from geomagnetic variations in the horizontal component observed at selected (10-13) observatories along the auroral zone in the northern hemisphere. To normalize the data a base value for each station is first calculated for each month by averaging all the data from the station on the five international quietest days. This base value is subtracted from each value of one-minute data obtained at the station during that month. Then among
the data from all the stations at each given time (UT), the largest and smallest values are selected. The AU and AL indices are respectively defined by the largest and the smallest values so selected. The symbols, AU and AL, derive from the fact that these values form the upper and lower envelopes of the superposed plots of all the data from these stations as functions of UT. The difference, AU minus AL, defines the AE index, and the mean value of the AU and AL, i.e.
(AU+AL)/2, defines the AO index. The term "AE indices" is usually used to represent these four indices (AU, AL, AE and AO). The AU and AL indices are intended to express the strongest current intensity of the eastward and westward auroral electrojets, respectively. The AE index represents the overall activity of the electrojets, and the AO index provides a measure of the equivalent zonal current.
the data from all the stations at each given time (UT), the largest and smallest values are selected. The AU and AL indices are respectively defined by the largest and the smallest values so selected. The symbols, AU and AL, derive from the fact that these values form the upper and lower envelopes of the superposed plots of all the data from these stations as functions of UT. The difference, AU minus AL, defines the AE index, and the mean value of the AU and AL, i.e.
(AU+AL)/2, defines the AO index. The term "AE indices" is usually used to represent these four indices (AU, AL, AE and AO). The AU and AL indices are intended to express the strongest current intensity of the eastward and westward auroral electrojets, respectively. The AE index represents the overall activity of the electrojets, and the AO index provides a measure of the equivalent zonal current.
Dataset Citation
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Dataset Identifiers
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ISO 19115-2 Metadata
gov.noaa.ngdc.stp.indices:G00584
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Ordering Instructions | Ordering Instructions: Data may be downloaded for no cost |
Distributor | Justin Mabie Space and Terrestrial Weather Specialist DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce (303) 497-6135 Justin.Mabie@noaa.gov |
Dataset Point of Contact | Justin Mabie Space and Terrestrial Weather Specialist DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce (303) 497-6135 Justin.Mabie@noaa.gov |
Time Period | 1957-01-01 to Present |
Spatial Bounding Box Coordinates |
West: -180.00
East: 180.00
South: -90.00
North: 90.00
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General Documentation |
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Edition | First |
Dataset Progress Status | Under development - data is currently in the process of being created |
Data Update Frequency | As needed |
Purpose | Geomagnetic Research |
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Global Change Master Directory (GCMD) Data Center Keywords
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Last Modified: 2015-09-18
For questions about the information on this page, please email: Justin.Mabie@noaa.gov
For questions about the information on this page, please email: Justin.Mabie@noaa.gov