Sea spray spume droplet production in high wind speeds

Abstract

Sea spray droplets are known to enhance the fluxes of momentum, heat, and mass at the air‐sea interface. Evaluating these fluxes depends in part on the so‐called “spray generation function”, the size distribution of droplets generated. At high wind speeds, spray is empirically observed to be plentiful near the ocean surface, however, the generation function has remained elusive both theoretically and experimentally. We report on a photographic laboratory experiment designed to directly quantify spume droplets observed at high wind speeds. The resulting sea spray concentration functions for spume droplets (diameter > 140μm) are reported for three high wind speed conditions (31.3, 41.2, and 47.1 ms−1). Our data suggest that large supra‐millimeter droplets are more prevalent than previously thought. We also observed a previously unreported spray generation mechanism whereby liquid sheets form at the crests of breaking waves and generate, upon breakup, a significant number of small spume drops.