Department of Physics, The Blackett Laboratory, Imperial College London, Prince Consort Road, London, SW7 2BW, UK
Received: 25 Oct 2013 – Discussion started: 27 Jan 2014
Abstract. Over the course of more than 10 years in operation, the calibration parameters of the outboard fluxgate magnetometer (FGM) sensors on the four Cluster spacecraft are shown to be remarkably stable. The parameters are refined on the ground during the rigorous FGM calibration process performed for the Cluster Active Archive (CAA). Fluctuations in some parameters show some correlation with trends in the sensor temperature (orbit position). The parameters, particularly the offsets, of the spacecraft 1 (C1) sensor have undergone more long-term drift than those of the other spacecraft (C2, C3 and C4) sensors. Some potentially anomalous calibration parameters have been identified and will require further investigation in future. However, the observed long-term stability demonstrated in this initial study gives confidence in the accuracy of the Cluster magnetic field data. For the most sensitive ranges of the FGM instrument, the offset drift is typically 0.2 nT per year in each sensor on C1 and negligible on C2, C3 and C4.
Revised: 29 May 2014 – Accepted: 06 Jun 2014 – Published: 11 Jul 2014
Alconcel, L. N. S., Fox, P., Brown, P., Oddy, T. M., Lucek, E. L., and Carr, C. M.: An initial investigation of the long-term trends in the fluxgate magnetometer (FGM) calibration parameters on the four Cluster spacecraft, Geosci. Instrum. Method. Data Syst., 3, 95-109, doi:10.5194/gi-3-95-2014, 2014.