Sverdrup transport refers to the large-scale movement of water in the ocean due to wind forcing, which is linked to the Earth's rotation.
- Option (A) is correct because Sverdrup transport is meridional (i.e., in the north-south direction) due to the Coriolis effect.
- Option (C) is also correct because the Sverdrup transport is directly influenced by the variation in the Coriolis parameter, which depends on latitude.
- Option (B) is incorrect because Sverdrup transport is not necessarily orthogonal to the wind direction; it depends on the specific wind patterns and latitudes.
- Option (D) is false because Sverdrup transport is a result of wind-driven currents, not purely ageostrophic currents.
Thus, the correct answers are (A) and (C).
Final Answer:
\[
\boxed{(A), (C) \, \text{Sverdrup transport is always in the meridional direction and depends on the variation of the Coriolis parameter.}}
\]