Fig. 1a: Adjusted steric height in 10~$m^2\,s^{-2}$ at the sea surface (Reid, 1989; reproduced with permission from Elsevier Science).
 
 

Fig. 1b: Adjusted steric height in 10~$m^2\,s^{-2}$ at 1000~$dbar$ (Reid, 1989; reproduced with permission from Elsevier Science.)