 |
| Titel |
Methods for Processing Satellite Constellation Measurements of Earth-External Magnetic Field Sources |
| VerfasserIn |
Rob Shore, Kathy Whaler, Susan Macmillan, Ciaran Beggan |
| Konferenz |
EGU General Assembly 2011
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250053254
|
|
|
|
|
|
| Zusammenfassung |
| The magnetic fields of space-borne current systems contribute significantly to magnetometer
measurements made by low Earth orbit (LEO) satellites. The accurate characterisation of
these spatially and temporally varying fields is important in order to make effective use of the
abundance of high-precision satellite magnetic data collected over the last decade. With the
launch of ESA’s Swarm satellite constellation mission in 2012, the future of LEO satellite
exploration of the geomagnetic field will be driven by constellation missions. We report on
advances in processing techniques for Earth-external field measurements made with a
constellation of satellites in LEO.
Stauning and Primdahl (2000) have proposed a method of applying Ampère’s law integral
along-track for a single satellite path to infer ionospheric current flow through a closed loop.
Ritter and Lühr (2006) have since proposed a higher resolution application of the Ampère’s
law integral designed to resolve radial ionospheric currents with the Swarm constellation. We
expand on these methods by posing the closed loop as the outline of the radial arc
formed by the overflight of two satellites at different altitudes. The CHAMP and
Ørsted LEO magnetic satellites are used for this purpose. Throughout the period
2000-2005, we solve for toroidal ionospheric current flow in the region between the two
satellites at discrete intervals. Analysis focuses on the characterisation of the toroidal
currents at different local times. Since the orbit of CHAMP decays faster than that of
Ørsted, a limited characterisation of changes in the toroidal currents with altitude is
possible.
The number of viable overlaps of the two satellites is relatively small. To avoid the
possibility of rapidly temporally variant magnetospheric fields biasing the toroidal field
solutions, we test the application of a further constellation-specific processing method. Using
a limited number of orbits of the upper satellite, we solve for the dipole component of the
magnetospheric field sources. Using a series of these solutions we can gauge the
magnetospheric field activity at that local time. An index of this type is suitable for the
processing of data from overlying satellite tracks. In future, a similar approach
could be used to provide an ‘instantaneous’ external field correction in a satellite
constellation.
References:
Ritter, P. & Lühr, H., 2006. Curl-B technique applied to Swarm constellation for
determining field-aligned currents, Earth Planets and Space, 58, 463-476.
Stauning, P. & Primdahl, F., 2000. First detection of global dawn-dusk ionospheric
current intensities using Ampère’s integral law on Ørsted orbits, Geophys. Res. Lett., 27,
3273-3276. |
|
|
|
|
|
|