Following discussions on the behaviour of the magnetic data from Swarm the scaling parameterisation of the VFM instrument has been adjusted. Using data from BOM until 1. August 2017 the scaling of the VFM data have been modeled using damped quadratic (in time) B-splines. Below the scalar residual plots for satellites Alpha and Bravo are shown together with the estimated B-spline scales (right axis, in green).
Recent analysis has additionally revealed that the full set of parameters of the degree and order 25 spherical harmonic models of the three components of dBSun can be well resolved by the data. Consequently, the estimation of the model parameters through truncated singular-value decomposition have been extended from ca. 800 to 2,000 degrees of freedom (the full equation system is not yet completely well conditioned). The effect of this modification is a noticeable reduction of the rms of the residuals and additional, smaller scales features in the maps of dBSun. The maps on the bottom of this page shows this as well as the changes in dBSun compared to the madel applied in the advanced version 0501 Level 1b magnetic data; the largest changes are seen in the y-component mainly due to the suppression of this component in previous estimations.
