An initial ULF wave index derived from 2 years of Swarm observations
The ongoing Swarm satellite mission provides an opportunity for better knowledge of the near-Earth electromagnetic environment. Herein, we use a new methodological approach for the detection and classification of ultra low-frequency (ULF) wave events observed by Swarm based on an existing time-f...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-03-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/36/287/2018/angeo-36-287-2018.pdf |
| Summary: | The ongoing Swarm satellite mission provides an opportunity for better
knowledge of the near-Earth electromagnetic environment. Herein, we use a new
methodological approach for the detection and classification of ultra
low-frequency (ULF) wave events observed by Swarm based on an existing
time-frequency analysis (TFA) tool and utilizing a state-of-the-art high-resolution magnetic field model and Swarm
Level 2 products (i.e., field-aligned currents – FACs – and the Ionospheric
Bubble Index – IBI). We present maps of the dependence of ULF wave power
with magnetic latitude and magnetic local time (MLT) as
well as geographic latitude and longitude from the three satellites at their
different locations in low-Earth orbit (LEO) for a period spanning 2 years
after the constellation's final configuration. We show that the inclusion of
the Swarm single-spacecraft FAC product in our analysis eliminates all the
wave activity at high altitudes, which is physically unrealistic. Moreover,
we derive a Swarm orbit-by-orbit Pc3 wave (20–100 MHz) index for the
topside ionosphere and compare its values with the corresponding variations
of solar wind variables and geomagnetic activity indices. This is the first
attempt, to our knowledge, to derive a ULF wave index from LEO satellite
data. The technique can be potentially used to define a new Level 2 product
from the mission, the Swarm ULF wave index, which would be suitable for space
weather applications. |
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| ISSN: | 0992-7689 1432-0576 |