The relation between wind speed and summer isothermal surface layer of water at ocean station P in the eastern subarctic Pacific Ocean

Bathythermographic and wind speed data collected at Ocean Weather Station P (50°N, 145°W) during April through August of the four years, 1956 through 1959, have been examined for relationships between the depth of the isothermal surface layer and the wind speed. It is shown that this depth can be related linearly to the mean wind speed averaged 12 hours in advance of the bathythermograph observation. The magnitudes of the standard error of estimate for the regression curves are almost the same as the standard deviations of the mixed-layer depths obtained from several series of more than eight bathythermograph observations made at intervals of 15 minutes, 1 hour, and 2 hours. It is concluded that the fluctuations of the mixed-layer depth, as indicated in the regression analysis and others, are due to the effects of internal waves. Improvement on the present relationship between the mixed-layer depth and wind speed would require specialized observations, in which, among others, the effects of the internal waves are smoothed out or eliminated and momentum flux from air to water monitored accurately.