Bottom water formation in the Weddell Sea resolved by principal component analysis and target estimation

The general mixing situation in the southern Weddell Sea is studied by prin cipal components analysis (PCA). A method for computing the fractions of th e assumed source waters in a given sample is presented. The method is appli ed to the formation of Antarctic Bottom Water in the southern part of the W eddell Sea. The algorithm is a combination of PCA and regression. The metho d can be used to compile the variation in a number of measured variables wi thout limitations of the variable count. Previous oceanographic knowledge i s combined with the score mixing patterns in order to estimate the number o f source waters and their compositions. In the application described, the p rinciple of this method is demonstrated with the variables temperature, sal inity and oxygen. Three source waters were indicated by PCA and the fractio ns of the two source waters, ice shelf water and warm deep water were calcu lated. (C) 1998 Elsevier Science B.V. All rights reserved.