Contribution of sea salt aerosol to the planetary clear-sky albedo

Abstract

In order to understand the response of the earth-atmosphere-aerosol system to climate forcing by greenhouse gases, it is essential to know the relative importance of the different factors within it. The purpose of the present work is to determine how much of the planetary clear sky albedo is due to the layer of sea salt aerosol that exists over the oceans. We calculate 94F (the change in solar flux entering at the top of the atmosphere) due to the presence of the sea salt aerosol layer, then show that this 9F is opposite in sign and comparable in magnitude to the predicted radiative forcing by increased levels of CO₂. Since sea salt is a stable component of the atmosphere, its radiative effects are already included in any measurement or calculation of the current planetary albedo. But when studying climates with stronger winds (leading to a greater sea salt aerosol loading), it is important to factor in the greater cooling due to sea salt, as an omission of this effect would lead to an underestimate of the planetary albedo.