Wave Breaking in Fetch-Limited Seas: Insights from the CLASI 2023 Field Campaign

Wave breaking is a fundamental mechanism for energy dissipation and air-sea exchange, especially in coastal and developing sea conditions. While optical remote sensing has been widely used to identify whitecaps, it often misses weak or foamless breakers and is challenging to deploy autonomously, limiting its effectiveness for process-level studies in remote settings.

In this study, we leverage comprehensive in-situ measurements from an array of Air-Sea Interaction Spar (ASIS) buoys deployed during the 2023 Coastal Land Air Sea Interaction (CLASI) campaign to quantify wave breaking and estimate dissipation in fetch-limited seas. Three ASIS buoys, each equipped with six high-frequency wave wires, were deployed along a 6–40 km cross-shore transect off the northern Florida Gulf Coast between January and March. In total, more than 2,500 of 30-min records and approximately 3.2 million individual waves were analyzed. Breaking waves were identified using the Liberzon et al. (2019) methodology, which is based on instantaneous phase and wavelet analysis. This approach detected 269,909 crests exceeding a statistical threshold for breaking.

For mature seas, the breaking fraction was strongly correlated with spectral bandwidth, but under young, narrow-banded conditions, it scaled with wave height. The energy dissipated by the observed breaking waves was estimated using several empirical models. Although total dissipation increased with sea state and wind development, dissipation under offshore flow did not vary monotonically with fetch. For instance, during strong wind events, dissipation was concentrated nearshore, whereas during storm decay, higher dissipation was observed at greater fetch distances.

These results offer direct measurements of wave breaking in coastal, fetch-limited environments and highlight the dominant role of local sea state development—rather than fetch length alone-in driving wave breaking. This work advances the physical understanding of nearshore-to-offshore energy transfer and supports future modeling efforts from the CLASI campaign.