Plate 8. Average surface flow, based on 40,000 observations of ship drift, 85,000 observations of satellite-tracked drifting buoys, and 8,000 modern current measurements. Sources and periods: historical ship drift, 1895-1993, National Ocean Data Center, NOAA; drifting buoys, 1986-1995: Atlantic Oceanographic and Meteorological Laboratory, NOAA, and Pelagic Fisheries Research Project, University of Hawaii; direct current measurements, 1987 to 1995: ADCP Archive Center, University of Hawaii / NOAA. Units: cm/s (25 cm/s = 0.5 knot).