"Eastward" indicates a vector component which is positive when directed eastward (negative westward). "Downward" indicates a vector component which is positive when directed downward (negative upward). "Downward eastward" indicates the ZX component of a tensor. Momentum flux is dimensionally equivalent to stress and pressure. It is a tensor quantity. In accordance with common usage in geophysical disciplines, "flux" implies per unit area, called "flux density" in physics.