Table 1

Dipole contribution to the yearly change in auroral zone surface area. The first column indicates which dipolar coefficient each row refers to. SV coefficients ${\dot{\beta }}_l^m$ are calculated as the yearly average over the 2015–2020 AD period from the IGRF-13 model, as in formula (4). The sensitivities $\partial A_i/\partial {\beta }_l^m$ are the same values as reported in Figure 3 (left panels). The temporal change contributions ∂A_i/∂t are obtained by multiplying $\partial A_i/\partial {\beta }_l^m$ with the corresponding ${\dot{\beta }}_l^m$. The column-wise sum of the ∂A_i/∂t values agrees with the l = 1 value reported in Figure 4 (left panel).

${\beta }_l^m$	${\dot{\beta }}_l^m$ [nT/year]	$\partial A_N/\partial {\beta }_l^m$ [km2/nT]	$\partial A_S/\partial {\beta }_l^m$ [km2/nT]	$\partial A_N/\partial t$ [km2/year]	$\partial A_S/\partial t$ [km2/year]
$g_1^0$	7.340	−1.339	−29.25	−9.825	−214.7
$g_1^1$	10.18	−26.67	226.2	−271.5	2303
$h_1^1$	−28.70	37.86	−80.12	−1087	2299