Non-triggered auroral substorms and long-period (1–4 mHz) geomagnetic and auroral luminosity pulsations in the polar cap
A study is undertaken into parameters of the polar auroral and geomagnetic pulsations in the frequency range 1–4 mHz (Pc5∕Pi3) during quiet geomagnetic intervals preceding auroral substorms and non-substorm background variations. Special attention is paid to substorms that occur under parameters...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-03-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/35/365/2017/angeo-35-365-2017.pdf |
| Summary: | A study is undertaken into parameters of the polar auroral and geomagnetic
pulsations in the frequency range 1–4 mHz (Pc5∕Pi3) during quiet
geomagnetic intervals preceding auroral substorms and non-substorm background
variations. Special attention is paid to substorms that occur under
parameters of the interplanetary magnetic field (IMF) conditions typical for
undisturbed days (<q>non-triggered substorms</q>). The spectral parameters of
pulsations observed in auroral luminosity as measured by a meridian scanning
photometer (Svalbard) in the polar cap and near the polar boundary of the
auroral oval are studied and compared with those for the geomagnetic
pulsations measured by the magnetometer network IMAGE in the same frequency
range. It is found that Pc5∕Pi3 power spectral density (PSD) is higher
during pre-substorm time intervals than for non-substorm days and that
specific variations of pulsation parameters (</q><q>substorm precursors</q>) occur
during the last 2–4 pre-substorm hours. |
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| ISSN: | 0992-7689 1432-0576 |