INTRA-SAMPLE, INTER-SAMPLE AND DOWN-CORE MICROVARIATION IN SEA-SURFACE TEMPERATURE ESTIMATES OBTAINED FROM PLANKTONIC-FORAMINIFERA IN THE NE ATLANTIC

Quantitative investigation of populations of planktonic foraminifera i n core-top and down-core (top 10 cm) samples from 14 sites in the NE A tlantic, between 19 degrees to 52 degrees N and 11 degrees to 30 degre es W, have revealed no intra-sample, inter-sample or down-core variabi lity beyond that to be expected on counts of 300 specimens (2 standard deviations, 95% confidence interval). Application of F20 transfer fun ction analysis shows that estimates of sea-surface temperature, based on these counts, fall within a range of +/-1.9 degrees C (precision). However, when these estimates are compared with 'actual' temperatures within the 1 degrees latitude/longitude squares containing the sites, the estimate errors range as high as +/-3.6 degrees C (accuracy). Thes e results indicate there is a continuing need to improve methods for e stimating proxy temperatures from planktonic foraminifera, in order to match the requirements of numerical modellers of past climates.