Particle motion in earths radiation belts. Comparison of gradient drift and drift due to convection and corrotaion

I would like to know if the drift due to the gradient of the earth’s magnetic field could be balanced by the sum of the drifts due to corrotation and conviction of the earth’s magnetosphere.

To my understanding the gradient drift can be written as:

$vec{V^{nabla B}_{D}} = frac{c e_{perp}}{q B} frac{3}{R}hat{phi}$

and the drift due to corrotation:

$vec{V^{cor}_{D}} = frac{vec{E^{cor}}times vec{B_{earth}}}{B^{2}}$ where $E^{cor} = – frac{R Omega_{earth}}{c} hat{R}$ and thus I would expect the drift due to corroation to be in the to be in the $-hat{phi}$ direction so why would one need the sum of the two ( convection and corrotation ) to balance the gradient dirft since the convection field (which to my undertanding is in the $hat{R}$?