Air-sea interaction processes at light winds observed from a coastal tower

Airflows, sea-surface waves, near-surface currents and X-band radar sea-ret urns were measured from a nearshore tower in 4-m deep water located in the Delaware Bay, during the passage of typical weather patterns. Intermittent violent momentum transfers, burstings, from air to water were clearly obser ved from measurements of the airflow turbulence. The scaling of mean period s between bursts and between sweeps with dominant wave period and the outer and inner variables of the turbulent airflow confirms that both, dominant wind waves and energy containing airflow eddies, share a role in the trigge ring of burstings. The three-dimensionality of the airflow in the field fac ilitates the reattachment manifested by the sweep events, and makes the lat ter similar to the bursts in terms of number and contribution to the mean R eynolds stress. The contribution of bursting events to the mean Reynolds st ress is stronger than in laboratory flows and exceeds 100%. Wavelet analysi s was applied to the surface wave data, and revealed uniformly distributed instants of bursts and sweeps over dominant wind wave profile. Using surfac e elevations and radar return data, no modifications of the surface roughne ss were found during bursting events.