Description:
<jats:p>Abstract. The China Seismo-Electromagnetic Satellite (CSES) was
launched in February 2018 into a polar, sun-synchronous, low Earth orbit. It
provides the first demonstration of the Coupled Dark State Magnetometer
(CDSM) measurement principle in space. The CDSM is an optical scalar
magnetometer based on the coherent population trapping (CPT) effect and
measures the scalar field with the lowest absolute error aboard CSES.
Therefore, it serves as the reference instrument for the measurements done
by the fluxgate sensors within the High Precision Magnetometer instrument
package. In this paper several correction steps are discussed in order to improve the
accuracy of the CDSM data. This includes the extraction of valid 1 Hz data,
the application of the sensor heading characteristic, the handling of
discontinuities, which occur when switching between the CPT resonance
superpositions, and the removal of fluxgate and satellite
interferences. The in-orbit performance is compared to the Absolute Scalar Magnetometer
aboard the Swarm satellite Bravo via the CHAOS magnetic field model.
Additionally, an uncertainty of the magnetic field measurement is derived
from unexpected parametric changes of the CDSM in orbit in combination with
performance measurements on the ground.
</jats:p>