Sea Spray Aerosol Production Controlled by Wind and Sea Surface Temperature

Sea spray aerosol (SSA) dominates the aerosol mass in the marine boundary layer and has an important influence on global climate. It is generally accepted that wind is the main driver for the production of SSA. This mechanism, however, requires observational support from a wide range of ocean environments. In addition, the role of other parameters, such as sea surface temperature (SST), in SSA production remains controversial. To address these questions, we use aircraft measurements of SSA made over the Pacific and Atlantic Oceans from pole to pole in different seasons during the NASA Atmospheric Tomography Mission (ATom). During ATom, the DC-8 aircraft continuously profiled from 150 m to 12 km altitude. For the present analysis, we focus on measurements in the marine boundary layer at altitudes below 200 m. We find that horizontal wind speed has a strong correlation with SSA volume and number concentration for particles greater than 0.5 μm from the global measurement, upholding the wind-driven mechanism. We further show that higher SST enhances the SSA production at a wide range of wind speed levels, and accounting for SST could enable better prediction of SSA. The relationship of SSA versus horizontal wind speed and SST is independent of seasonality, suggesting that a uniform parameterization of SSA using these parameters is favorable. Updating current SSA-predicting modules in models using the newly derived parameterization from this study may improve our quantification of the radiative forcing of SSA and its role in climate.