Solar heating of the upper ocean is a primary energy input to the
ocean-atmosphere system, and the vertical heating profile is modified by
the concentration of phytoplankton in the water, with consequences for
sea surface temperature and upper ocean dynamics. Despite the
development of increasingly complex modeling approaches for radiative
transfer in the atmosphere and upper ocean, the simple parameterizations
of radiant heating used in most ocean models are plagued by errors and
inconsistencies. There remains a need for a parameterization that is
reliable in the upper meters and contains an explicitly spectral
dependence on the concentration of biogenic material, while maintaining
the computational simplicity of the parameterizations currently in use.
In this work, we assemble simple, observationally-validated physical
modeling tools for the key controls on ocean radiant heating, and
simplify them into a parameterization that fulfills this need. We then
use observations from 64 spectroradiometer depth casts across 6 cruises,
13 surface hyperspectral radiometer deployments, and 2 UAV flights to
probe the accuracy and uncertainty associated with the new
parameterization. We conclude with a case study using the new
parameterization to demonstrate the impact of chlorophyll concentration
on the structure of diurnal warm layers, an investigation that was not
possible to conduct accurately using previous parameterizations. The
parameterization presented in this work equips researchers to better
model global patterns of sea surface temperature, diurnal warming, and
mixed-layer depths, without a prohibitive increase in complexity.