UPPER OCEAN SALINITY BALANCE IN THE WESTERN EQUATORIAL PACIFIC

The upper ocean salinity balance in the western equatorial Pacific war m pool was evaluated using up to 2.5 years of data (September 1991 thr ough April 1994) from the Coupled Ocean-Atmosphere Response Experiment 's enhanced monitoring array of moorings. At the central mooring site (0 degrees, 156 degrees E), precipitation had a record-length mean of 4.5 m yr(-1), while evaporation had a mean of 1.4 m yr(-1). This exces s surface freshwater flux was balanced primarily by vertical mixing (e stimated as the residual of a salt budget calculation) and by zonal ad vection. For timescales between a month and 2.5 years, surface salinit y variability was dominated by zonal advection and only weakly correla ted with precipitation, consistent with the concept of a zonally migra ting ''fresh pool.'' The effects of precipitation on local surface sal inity variations were more apparent for timescales shorter than a mont h. Shallow rain ''puddles'' tended to form in a matter of hours. Howev er, owing to the combination of mixing and advection, these precipitat ion-generated freshwater puddles were typically short-lived.