Comparing historical and modern methods of sea surface temperature measurement – Part 1: Review of methods, field comparisons and dataset adjustments

摘要

Sea surface temperature (SST) has been obtained from a variety of differentplatforms, instruments and depths over the past 150 yr. Modern-dayplatforms include ships, moored and drifting buoys and satellites. Shipboardmethods include temperature measurement of seawater sampled by bucket andflowing through engine cooling water intakes.Here I review SST measurement methods, studies analysing shipboard methodsby field or lab experiment and adjustments applied to historical SSTdatasets to account for variable methods. In general, bucket temperatureshave been found to average a few tenths of a °C cooler thansimultaneous engine intake temperatures. Field and lab experimentsdemonstrate that cooling of bucket samples prior to measurement provides aplausible explanation for negative average bucket-intake differences. Thesecan also be credibly attributed to systematic errors in intake temperatures,which have been found to average overly-warm by >0.5 °C on some vessels. However, the precise origin of non-zero averagebucket-intake differences reported in field studies is often unclear, giventhat additional temperatures to those from the buckets and intakes haverarely been obtained. Supplementary accurate in situ temperatures arerequired to reveal individual errors in bucket and intake temperatures, andthe role of near-surface temperature gradients. There is a need for furtherfield experiments of the type reported in Part 2 to address this and otherlimitations of previous studies.