SOME OBSERVATIONS OF THE DIURNAL HEAT WAVE IN THE OCEAN1

The diurnal heat wave was observed over several days at a station in the subtropical North Atlantic Ocean. Measurements were made every 30 min using an in situ temperature-salinity-depth recorder; the isotherms were plotted (to an accuracy 0.01C) at 2-m depth intervals. For a day of average conditions, the maximum penetration of the discernible heat wave was to about 30 m, but throughout the cycle approximately 80% of the gain of heat in the water column was confined to the top 14 m. Estimates of the coefficient of vertical eddy diffusion were made at several depths, and for the top 4 m the daily values varied between 93 cm2/sec and 432 cm2/sec.