Is the North Pacific in Sverdrup balance along 24°N?


  • Susan L. Hautala,

  • Dean H. Roemmich,

  • William J. Schmilz Jr.


Hydrographic data from a zonal section along approximately 24°N is used to demonstrate that basin-scale baroclinic geostrophic transport agrees with the Sverdrup relation in the subtropical North Pacific. Moreover, profiles of vertical velocity, as derived from the linear vorticity equation, are consistent with constraints upon deeper flows. Sverdrup balance from the eastern boundary to about 137°E is in accord with most other elements of the general circulation to the extent that they are known. In the Philippine Sea, west of 137°E, the results suggest that a mean northward flow of 5–10 Sv occurs. In the northeast Pacific Basin, a significant subbasin-scale deviation of about 7 Sv from Sverdrup balance is revealed; this deviation is distinguished by excess shallow southward flow near the water mass boundary between the subtropical gyre and the subpolar waters adjacent to the American coast.