Development of a Ocean Surface Albedo Scheme with Wave Breaking Factor

Ocean surface albedo (OSA) plays a important role in the energy balance of the climate systems. In climate models, it is typically treated as a constant or represented by a simplistic function of Solar Zenith Angle (SZA). However, research by Jin (2011) indicates that OSA can be significantly influenced by whitecaps under moderate to high surface wind conditions (denoted as Jin11 scheme). Whitecap coverage is a key factor in this parameterization, often expressed as a power function of surface wind speed. Given that water depth and wave height are associated with wave breaking—of which whitecaps are the primary manifestation—the ratio of theoretical wave height to water depth has been incorporated into the Jin11 scheme for adjustment. This modification reflects the characteristic that certain areas are more prone to whitecaps under identical wind conditions.

In this study, we incorporated this improved OSA parameterization scheme into the Community Earth System Model Version 2 (CESM2) and conducted coupled simulation experiments. The numerical results show an alleviation of the excessive reduction in sea surface temperature in the equatorial ocean, the North Pacific subtropical gyre circulation, and the southern westerly wind belt as simulated by the Jin11 scheme. Additionally, longwave radiative heating in the tropical regions is significantly altered after accounting for the wave breaking factor. Precipitation simulations over the northwest Pacific, the tropical Indian Ocean, and the Indo-Pacific Convergence Zone show improvements, while the induced substantial changes in latent heating have further affected vertical motion and convective activity.