Compensation of Ocean Latent Heat to Stratospheric Aerosol Injection Induced Cooling and Its Comparison to Volcanic Aerosols

Abstract

Latent heat (LH) flux is one of the important components of sea surface heat flux, due to the remarkable evaporation occurring at the ocean‐atmosphere interface and is demonstrated to compensate partial oceanic heat loss induced by large volcanic eruptions. Here we show that ocean LH acts to damp aerosol‐induced cooling under the Stratospheric Aerosol Geoengineering Large Ensemble simulation, in which the global mean surface temperature and its meridional gradients are strategically fixed to their 2020 values. However, the LH compensation under continuous stratospheric aerosol intervention differs significantly from that of the impulsive Tambora volcanic perturbation, especially in regions where circulation anomalies and its contribution to LH release significantly weaken. By reducing the stored energy in the ocean and consequently decreasing the sea surface saturated specific humidity, the stratospheric aerosol intervention suppresses the sensitivity of ocean's ability to modulate radiative perturbation. The stratospheric aerosol intervention versus Tambora differences are especially pronounced in the trade wind subtropics and the west boundary current regions, where the land‐sea thermal response contrast and longitudinal sea surface temperature gradient pronounced under Tambora perturbation is suppressed under the stratospheric aerosol intervention due to ocean adjustment. These results reveal the general compensation role, yet significant process differences, of ocean LH responses under the two scenarios, and call for caution when inferring hydroclimatic consequence of the sustained stratospheric aerosol injection scenarios from volcanic analogue, especially in the LH hot spot regions.