Modulation of cloud Droplets and radiation over the North Pacific by sulfate aerosol erupted from Mount Kilauea

Mount Kilauea in the Hawaiian Islands experienced an active eruption from March until the end of December 2008 and showed a large-scale impact on aerosol, cloud microphysical properties and atmospheric radiation over the North Pacific. We analyzed the atmospheric impact of this eruption based on the satellite retrievals and 3-D global chemistry-radiation coupled transport model. We showed that approximately 1.8 Tg (±1.2 Tg) release of SO₂ was estimated from this eruption, which oxidized into sulfate aerosol during transport to the northwest Pacific Ocean. The volcanic sulfate aerosol layer covering a large area (~6.5 × 10⁶ km²) of the lower troposphere over the North Pacific for several months was confirmed from both satellite and model results. Sulfate aerosols affected the formation of cumulus water clouds by reducing the typical cloud effective radius by ~23% and increasing the cloud fractional coverage over the ocean from 9.1% to 13.4% (over the region 170°E-160°W, 10°N-20°N). The affected cumulus clouds appeared whiter than normal and thus reflected more solar radiation. Consequently, satellite observations revealed an approximately 1% increase in albedo at the top of the atmosphere in the area along main volcano plume trajectory, which induced an approximately -5 W m^-2 change in the shortwave radiation budget.