Annual and Interannual Variability of Steric Sea Level along Line P in the Northeast Pacific Ocean

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Abstract Twenty-five and 22 years of hydrographic-STD casts from Station P and Line P, respectively, have been utilized to describe the annual and interannual variability of thermosteric, halosteric and total steric heights. In the offshore region beyond the continental slope thermosteric effect dominates the annual cycle of total steric height, whereas near the coast over the continental shelf halosteric effect controls the height. In between, over the slope, both temperature and salinity effect contribute almost equally to the annual cycle of height. Offshore, the annual change of steric height relative to 1000 db resembles that relative to 100 db, but as the coast is approached, the change due to the deeper water becomes more important. The heat budget within the upper 100 db of water determines most of the annual range of steric height offshore, but near the coast both dilution due to precipitation and runoff in winter and concentration due to upwelling of cool, saline water in summer govern the annua...