Evaluation of Sea Surface Temperature Measurements from Drifting Buoys

Three drift-buoy designs have been deployed since 1988 in substantial numbers in the tropical Pacific Ocean by United States participants as part of the Tropical Ocean Global Atmosphere (TOGA) Pan Pacific Surface Current Study. These include the Low Cost Tropical Drifter designed and built at the Atlantic Oceanography and Meteorological Laboratory, the Low Cost Drifter (LCD) designed and built by the Massachusetts Institute of Technology Draper Laboratories, and the Minister Drifter designed and built at the Scripps Institution of Oceanography and built by Tecnocean Inc., San Diego, California, which has subsequently become known as the World Ocean Climate Experiment standard drifter. This report contains an evaluation of the performance of the sea surface temperature measurement system carried by these buoy designs. Based on comparisons of the monthly mean SST derived from the available XBT and CTD casts and on intercomparisons of among each of the buoy types, all three designs appear to include a warm bias in the surface temperatures they report. The LCD showed a larger mean bias and diurnal variation from solar heating than the other two buoy types. This difference is probably due to the location chosen for its sensor, resulting in poor thermal contact with the surrounding water.