Ocean Mixed Layer Radiant Heating and Solar Penetration: A Global Analysis

Abstract

Abstract A hybrid parameterization for the determination of in-water solar fluxes is developed and applied to compute the flux of solar radiation that penetrates beyond the upper-ocean mixed layer into permanent pycnocline waters on global space and climatological timescales. The net flux of solar radiation at depth is modeled using values of the solar flux incident at the sea surface, derived from the International Satellite Cloud Climatology Project dataset, and in-water attenuation coefficients, determined using upper ocean chlorophyll concentration supplied by Coastal Zone Color Scanner imagery. Solar radiation penetration can be a significant term (20 W m−2) in the mixed layer heat budget for tropical regions. In mid- and high-latitude regions, the annual solar flux entering permanent pycnocline waters is small (<5 W m−2). However, solar penetration in these regions is important on seasonal timescales since annual cycles in incident solar flux, upper-ocean chlorophyll concentration, and mixed layer d...