|Paper title||Swarm accelerometers data processing and anomaly analysis|
|Form of presentation||Poster|
As part of the identical scientific payloads of the Swarm satellites, the electrostatic accelerometers are aimed to estimate non-gravitational forces acting on each satellite, as needed in the near-Earth space environmental studies. The hybridized non-gravitational accelerations could be constructed, using the GPS receiver data for the lower frequency range and the accelerometer data for the higher frequency range. Such a synergy was successfully realized and resulted in the calibrated non-gravitational along-track accelerations of the Swarm C satellite (Level 2 products ACCxCAL_2) for the full mission time, starting from February 2014. However, Swarm A Level 2 accelerations are recently released only for the first year of mission, and the Swarm B accelerometer data are still unavailable. Nevertheless, the one-year overlap of the released Swarm C and Swarm A Level 2 accelerations for the first time allows to exploit the planned constellation benefits for the thermospheric studies.
Because of unexpected and intensive data anomalies at the Level 1B, the considerable processing efforts are required to maintain the Level 2 accelerations at the acceptable quality level. Therefore, processing of Swarm accelerations differs essentially from that of other missions. This presentation provides details on the processing algorithms and data quality assessment as needed for the Swarm accelerometer data users. Special attention is given to anomalies analysis, triggered by external impacts from the environment and/or spacecraft micro-seismic events, and generated possibly because of the after-launch hardware mechanical damages or other instrumental issues. The following data anomalies will be discussed: random and systematic abrupt bias changes (steps); regular discharge-like spikes, which are spatially correlated in a form of specific patterns of lines and spots; impulse noise and resonant harmonics in electronics; temperature-induced slow bias changes; damages or signal inversions at the eclipse entries; non-nominal reference signal partitioning during the calibration maneuvers. With an improved understanding of the sensor behavior, Swarm accelerometers collect a valuable information as a technology demonstrator for future satellite missions.