Effect of wind speed on the size distribution of biogenic gel particles in the sea surface microlayer: Insights from a wind wave channel experiment
Abstract. Biogenic gels particles, such as transparent exopolymer particles (TEP) and Coomassie stainable particles (CSP), are important components in the sea-surface microlayer (SML). The accumulation of gel particles in the SML and their potential implications for gas exchange and emission of primary organic aerosols have generated considerable research interest in recent years. Changes in the particle-size distribution (PSD) can provide important information for the understanding of physical and chemical processes involving gel particles, such as aggregation, degradation or loss. So far, little is known regarding the influence of wind speed on the size distribution of marine gel particles in the surface microlayer. Here, we present results on the effect of different wind speeds on the PSD of TEP and CSP during a wind wave channel experiment in the Aeolotron. Total area of TEP and CSP were exponentially related to wind speed in the SML. At wind speeds 8 m s−1 also significantly altered the PSD slope of TEP in the 2–16 μm size range toward smaller size. Changes in spectral slopes at wind speeds > 8 m s−1 were more pronounced for TEP than for CSP indicating a high aggregation potential for TEP in the SML, potentially enhancing the export of TEP by aggregates settling out of the SML. Our experiment provided evidence for the control of wind speed on the accumulation of biogenic gel particles and their PSD changes, providing a useful insight into particle dynamics and biophysical processes at the interface between air and sea.