Earth Planets Space, Vol. 65 (No. 11), pp. 1201-1222, 2013
Terence J. Sabaka1, Lars Tøffner-Clausen2, and Nils Olsen2
1Planetary Geodynamics Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
2National Space Institute, Technical University of Denmark, Lyngby, Denmark
(Received March 27, 2013; Revised September 6, 2013; Accepted September 9, 2013; Online published November 22, 2013)
An advanced algorithm, known as the ``Comprehensive Inversion" (CI), is presented for the
analysis of Swarm measurements to generate a consistent set of Level-2 data products to be
delivered by the Swarm ``Satellite Constellation Application and Research Facility"
(SCARF) to the European Space Agency (ESA). This new algorithm improves on a previously developed
version in several ways, including the ability to process ground-based observatory data, estimation
of rotations describing the alignment of vector magnetometer measurements with a known reference
system, and the inclusion of ionospheric induction effects due to an a priori
3-dimensional conductivity model. However, the most substantial improvements entail the
application of a mechanism termed ``Selective Infinite Variance Weighting" (SIVW), which mitigates
the effects of non-zero mean systematic noise and allows for the exploitation of gradient
information from the low-altitude Swarm satellite pair to determine small-scale
lithospheric fields, and an improvement in the treatment of attitude error due to noise in
star-tracking systems over previously established methods. The advanced CI algorithm is validated
by applying it to synthetic data from a full simulation of the Swarm mission, where it is
found to significantly exceed all mandatory and most target accuracy requirements.
Key words: Swarm, Earth's magnetic field, comprehensive modeling, core, lithosphere, ionosphere, magnetosphere, electromagnetic induction.