Spatial Variations in Surface Microlayer Surfactants and their Role in Modulating Air‐Sea Exchange

The potential role of surface microlayer surfactants in modulating air-sea exchange processes in the low wind regime is examined. Variations in surfactant concentration and surface microlayer enrichments are compared with variations in the small-scale wave slope spectrum on large and small spatial scales over large gradients in biological productivity and organic matter level. Surfactant films are shown to strongly reduce the one-sided omnidirectional wave slope S(k) at wave numbers k = 100 - 400 rad m -1 . The degree of reduction is dependent on the excess microlayer surfactant relative to the underlying water rather than bulk surfactant concentration. The observed wave slope reductions imply corresponding reductions in mass and momentum exchange.