Use the Divergence Theorem to evaluate $ \iint_S \textbf{F} \cdot d\textbf{S} $, where $ \textbf{F}(x, y, z) = z^2x \, \textbf{i} + (\frac{1}{3}y^3 + \tan z) \, \textbf{j} + (x^2z + y^2) \, \textbf{k} $ and $ S $ is the top half of the sphere $ x^2 + y^2 + z^2 = 1 $. [$ \textit{Hint:} $ Note that $ S $ is not a closed surface. First compute integrals over $ S_1 $ and $ S_2 $, where $ S_1 $ is the disk $ x^2 + y^2 \leqslant 1 $, oriented downward, and $ S_2 = S \cup S_1 $.]