Observations of the scale and occurrence of breaking surface waves

Breaking of surface waves was monitored with conductivity measurements at w ind speeds up to 18 m s(-1). This method of wave breaking detection is well defined but excludes microbreakers and breaking of very short gravity wave s. Observations in both fetch limited and open ocean conditions reveal that wind speed or wave age are insufficient to characterize breaking activity. A scaling of the breaking frequency based on wind energy input is proposed . This scaling collapses the authors' diverse datasets, consistent with ene rgy dissipation being determined primarily by the high frequency tail of th e wave spectrum. Breaking waves with significant air entrainment were obser ved to have wavelengths between similar to 0.1 of the dominant waves and th at of the largest wind waves. The median value of the period of breaking wa ves is approximately half the period of the dominant waves and the mean hei ght of breaking waves is similar to 0.7 times the significant wave height. Less than 10% of observed breaking events resulted in deeply penetrating ai r entrainment (>0.2 m), suggesting the predominance of spilling breakers.