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.
Plain Language Summary
The ocean constantly exchanges heat and moisture with the atmosphere through processes called sensible and latent heat fluxes. Scientists typically estimate these fluxes without considering the ocean surface area change due to waves. But in reality, waves, mostly generated by winds, make the surface wrinkled, increasing the area available for air‐sea exchange of heat and moisture. This study shows that these wrinkles, captured by a measure called mean square slope (MSS), enhance the effective ocean surface area by about 2% as a global average. As a result, current methods slightly underestimate how much heat and moisture move from the ocean into the atmosphere. By applying a correction based on MSS to decades of climate data, we find that the global estimates of these heat fluxes should be a bit higher—especially in regions like the western boundary currents and subtropical zones. These adjustments can add up over time and affect how we understand climate change and energy flow across the Earth's surface.
Key Points
Ocean wave slopes increase the effective air‐sea exchange area by ∼2%, leading to systematic underestimation of turbulent heat fluxes in standard bulk models
Applying a mean square slope‐based correction to ERA5 (1940–2024) increases global air‐sea sensible heat flux by 0.29 W/m2 and latent heat flux by 2.34 W/m2
The corrections exhibit strong spatial and seasonal variability, and their cumulative effects can influence global energy budgets and climate model accuracy