Plots of the time series of the residual magnetospheric field measured by Swarm A during the St Patrick storm 2015. The light blue line shows the satellite interpolated measurements at the modelled time, and the colour dots show the model evaluated at the interpolated satellite positions. The colours indicate the coefficient of determination, R², for the model linear regression fit to the Gauss coefficients. Colour values close to 1 (yellow) indicate a good linear fit to the time interval chosen for the model (8 h in this case) and values close to zero (dark purple) indicate that the fit is not good and the data variation within the time window is large.