The influence of optical water type on the heating rate of a constant depth mixed layer

A simple heat budget model for a radiation‐dominated mixed layer of constant depth is presented. In this model the influence of the vertical irradiance (heat flux) profile is examined by means of the Jerlov 1976 optical water type classification. It is shown that the vertical irradiance profile is important in determining the mixed layer heating rate. The heating rate varies greatly as a function of water type, mixed layer depth, and diffusivity beneath the mixed layer, ranging from 0.098°C/day for oceanic water type I with a mixed layer depth of 20 m and diffusivity beneath the mixed layer of 1.0 cm 2 s −1 to 0.316°C/day for coastal type 9 with a mixed layer depth of 10 m and zero diffusivity beneath the mixed layer, a variation of more than a factor of 3.