This paper presents maps of the distribution of 29 planktonic foraminiferal species in 191 North Atlantic Ocean core tops and describes and tests a transfer function (F13) derived from these data by factor analysis and regression techniques. This transfer function relates six assemblages of planktonic foraminifera to seasonal temperatures and salinities at the sea surface and at a depth of 100 m. The data represent revision and expansion of a data base used previously to derive another transfer function (F3). The new set of data comes mostly (81%) from trigger-weight cores, has greater geographical coverage and depth range, includes faunas from shallow and upwelling waters, and incorporates samples with moderately high dissolution. The transfer function derived from these data yields estimates that have 80% confidence intervals ranging from ±1.5° to ±2.8°C and from ±0.367‰ to ±0.64‰, depending on season and depth. Estimates that fall outside the 80% confidence intervals are randomly distributed in latitude, distance from continents, depth of water, and dissolution effects.
Two independent sets of data were used to test the equations: 60 core tops from the South Atlantic and five short cores from the North Atlantic. For the sea-surface temperatures estimated from the core tops, 78% to 82% of the derived temperatures fall within the previously calculated 80% confidence intervals. Application of F13 to the five short cores located between 0° and 54°N yields reasonable temperature and salinity ranges for the past 20,000 yr.