Fig. 2

Residuals of the scalar field \(\Delta F\) and differences \(\Delta \delta F\) (top) and the vector field \(\Delta \mathbf {B}\) and differences \(\Delta \delta \mathbf {B}\) (bottom) from CIY4 for Swarm Alpha with respect to Kp activity level. The “X” denote the weighted means while the bars indicate weighted standard deviations. The dashed lines indicate \(\pm\, 99\%\) of the residual ranges. Note that the vector components for the field data are \(\textit{BP3}\), but are \(\textit{NEC}\) for the difference data