On the global flux of atmospheric sea salt

Abstract

The calculated global wet and dry deposition fields of atmospheric sea‐salt to the ocean surface, obtained using a sea‐salt mass size distribution appropriate for an elevation of 15 m above mean sea level (AMSL), are examined on a monthly basis with 5° × 5° latitude‐longitude spatial resolution. A monthly Gaussian frequency distribution of wind speeds is computed for each 5° × 5° area. This global wind speed climatology is coupled with equations relating atmospheric sea‐salt removal processes to wind speed. This allows us to estimate various global properties of atmospheric sea salt, such as the mass median radius of a log‐normal sea‐salt mass distribution, the deposition velocities of both wet and dry atmospheric sea‐salt deposition and the global deposition field of atmospheric sea‐salt. The global dry depositional flux of atmospheric sea salt through a plane 15 m AMSL is 0.8–2.2 × 1016 g yr−1. The global wet depositional flux of atmospheric sea‐salt is 0.15–0.45 × 1016 g yr−1. The global flux of atmospheric sea salt is thus approximately 1–3 × 1016 g yr−1. The largest atmospheric sea‐salt deposition is found in the high‐latitude regions of both hemispheres. While the dry deposition of atmospheric sea salt dominates wet deposition removal on a global scale, over areas associated with the Intertropical Convergence Zone atmospheric sea salt is removed with comparable efficiency by wet and dry deposition.