  Given an annular link $L$, there is a corresponding augmented link
$\widetilde{L}$ in $S^3$ obtained by adding a meridian unknot component to $L$.
In this paper, we construct a spectral sequence with the second page isomorphic
to the annular Khovanov homology of $L$ and it converges to the reduced
Khovanov homology of $\widetilde{L}$. As an application, we classify all the
links with the minimal rank of annular Khovanov homology. We also give a proof
that annular Khovanov homology detects unlinks.
