Dynamic of the upper cross-isobath's flow on the northern South China Sea in summer

Based on simulation, the summer upper-ocean cross-isobath's flow on the Northern South China Sea has been analyzed. East to Xisha water, the cross-isobaths flow mainly onshore, including little offshore flows. On Xisha water, the sea water flows onshore on the north side and is reversed on the other side. The momentum balance shows that the along-isobath's barotropic pressure gradient determines the distribution of the cross-isobath flow. Theoretical analysis shows that the along-isobath's density gradient and the windstress curl are two important factors that determine the along-isobath's sea surface height gradient, which is the main contributor to the barotropic pressure gradient. Numerical experiments demonstrate that the temperature distribution dominates the along-isobath's density gradient and determines the along-isobath's sea surface height gradient.