Effects of solar wind density on auroral electrojets and brightness under influence of substorms
Using the auroral electrojet indices and Polar Ultraviolet Imager auroral images, we examined two fortuitous events during which the solar wind density had clear enhancements while the other solar wind parameters were relatively constant. Two electrojet enhancements were found in each event. Th...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2009-01-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/27/113/2009/angeo-27-113-2009.pdf |
| Summary: | Using the auroral electrojet indices and Polar Ultraviolet
Imager auroral images, we examined two fortuitous events
during which the solar wind density had clear enhancements
while the other solar wind parameters were relatively constant.
Two electrojet enhancements were found in each event.
The first electrojet enhancement was likely to be related to
a substorm in which an auroral bulge
appeared at premidnight. The second electrojet enhancement
was driven by the density enhancement in the solar wind.
The auroral oval became wider in latitude and the auroral distribution
became dispersed after the density enhancement arrived at the Earth.
The total auroral power integrated over the entire nightside
region from 50 to 80° MLAT, however, did not
increase significantly in response to the density enhancement.
Our interpretation is that the substorm that occurred prior to
the solar wind density enhancement had drained out a significant
portion of the stored energy in the magnetotail; therefore, less
precipitation energy was deposited into the auroral ionosphere
by the density enhancement. |
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| ISSN: | 0992-7689 1432-0576 |