The variation of the total magnetic flux in the tail lobes and in the whole tail as a function of X _GSM for ϕ = +35° and ϕ = 0 from the BATSRUS model runs at simulation time t = 90 min. (Because the model uses a symmetric intrinsic geomagnetic field the ϕ = −35° case gives the same information as the ϕ = +35° case with the hemispheres flipped). For ϕ = 0 the variation for the two lobes is the same (the orange line has been offset from the green by a linewidth so it can be seen). For ϕ = +35° the flux is lower in the northern (“summer”) lobe than the southern (“winter”) and the sum of the two (the black line) is lower than the sum for ϕ = 0 (the black line).