Continental runoff and effects on the North Atlantic Ocean Subtropical Mode Water

Interannual salinity variations in North Atlantic Subtropical Mode Water (S TMW) are well known although the cause is less well understood. Attempts to model local salinity variation with local evaporation and precipitation ha ve not been successful and some authors invoke advection of low salinity wa ter as the cause. Examination of the STMW and North American river runoff d ata suggests that runoff may partly explain the salinity variations. It is known that low salinity water resulting from Mississippi River outflow is t ransported well past Cape Hatteras. Spearman Rank Correlation analysis and spectra and cross-spectra Fourier correlation analysis both show that river flow is significantly inversely correlated with STMW salinity. This result suggests that North American river flow may have an influence on the salin ity of STMW.