Reply on RC2

Abstract. All exchange between the ocean and atmosphere has to cross the sea surface microlayer (SML), yet the SML impact on modulating air-sea exchange rates remains poorly understood. Surfactants, including biopolymers, can influence exchange rates by altering the rheological properties of the SML, damping surface turbulence, and capillary wave formations. We investigated the impact of wind speed on SML biopolymer enrichment, surface roughness and interfacial surfactant coverage at the Heidelberg ‘Aeolotron,’ a large annular wind-wave facility filled with 18.000 L seawater. Our results show that biopolymer enrichment, specifically the enrichment of polypeptides and polysaccharides, in the SML declined sharply at wind speeds above 6 m/s, coinciding with a sudden increase in the Mean Square Slope (MSS) of waves by 2–3 orders of magnitude. At wind speed