Given two deterministic parity automata $A_1=(Q_1,\Sigma,\delta,q_{01},c_1)$ and $A_2=(Q_2,\Sigma,\delta,q_{02},c_2)$ with the finite set of states $Q_i$, the finite alphabet $\Sigma_i$, the transition function $\delta_i : Q_i \times \Sigma \rightarrow Q_i$, the initial state $q_{0i}$ in $Q_i$, and the coloring function $c_i : Q_i \rightarrow \mathbb{N}$, with $i \in\{0,1\}$.
How is the intersection of two deterministic parity automata formally defined? In particular, how are the coloring functions combined?