On a principal component analysis to estimate the upper oceanic variability of salinity: application to the western, tropical Pacific Ocean

We propose a new approach to estimate the vertical variability of the salin ity field. The method is based on combined vertical modes of temperature an d salinity, and reconstructs salinity profiles via a weighted least-squares procedure. The modes are defined as the empirical orthogonal functions alo ng the water column. The major advantages of this new approach over using a simple T-S relationship are that interannual variability is better taken i nto account and that the method combines different sources of information s uch as temperature profiles and sea surface height in a consistent way. The present results estimate the salinity along 165 degrees E in the western P acific Ocean for the 1993-1997 period and emphasize the importance of the s alinity on sea level variability. ((C) 1999 Academie des sciences / Edition s scientifiques et medicales Elsevier SAS.).