Ocean Wave Slope Effects on Global Air-Sea Turbulent Heat Flux

Abstract

Ocean surface turbulent heat fluxes, sensible heat flux (SHF) and latent heat flux (LHF), are crucial for regulating the Earth's energy and water budgets. However, standard bulk flux algorithms neglect the enhanced surface area caused by the ocean wave slopes. This study introduces a geometric correction to SHF and LHF based on the mean square slope (MSS) of ocean waves, derived analytically and applied globally using ERA5 reanalysis data from 1940 to 2024. After correcting MSS to account for unresolved high-frequency waves, we estimate that the effective air-sea interface area is enhanced by ∼2% on average, leading to mean corrections of 0.29 W/m2 for SHF and 2.34 W/m2 for LHF. Climatological trends in MSS and LHF corrections reveal statistically significant increases over the past several decades. These corrections are spatially and seasonally variable, and may have cumulative impacts on climate simulations, ocean heat content assessments, and flux-dependent satellite retrievals.