In this work we present a unique set of coincident and collocated high‐resolution observations of surface currents and directional properties of surface waves collected from an airborne instrument, the Modular Aerial Sensing System, collected off the coast of Southern California. High‐resolution observations of near surface current profiles and shear are obtained using a new instrument, “DoppVis”, capable of capturing horizontal spatial current variability down to 128 m resolution. This data set provides a unique opportunity to examine how currents at scales ranging from 1 to 100 km modulate bulk (e.g., significant wave height), directional and spectral properties of surface gravity waves. Such observations are a step toward developing better understanding of the underlying physics of submesoscale processes (e.g., frontogenesis and frontal arrest) and the nature of transitions between mesoscale and submesoscale dynamics.

Significant wave height (SWH) stems from a combination of locally generated “wind‐sea” and remotely generated “swell” waves. In the Northern and Southern Hemispheres, wave heights typically undergo a sinusoidal annual cycle, with larger SWH in winter in response to seasonal changes in high‐latitude storm patterns that generate equatorward propagating swell. However, some locations deviate from this hemispheric‐scale seasonal pattern in SWH. For example, in the California coastal region, local wind events occur in boreal spring and summer, leading to a wind speed (WSP) annual cycle with a distinct maximum in boreal spring and a corresponding local response in SWH. Here ocean regions with a WSP annual cycle reaching a maximum in late spring, summer, or early fall are designated as seasonal wind anomaly regions (SWARs). Intra‐annual variability of surface gravity waves is analyzed globally using two decades of satellite‐derived SWH and WSP data. The phasing of the WSP annual cycle is used as a metric to identify SWARs. Global maps of probability of swell based on wave age confirm that during the spring and summer months, locally forced waves are statistically more likely in SWARs than in surrounding regions. The magnitude of the deviation in the SWH annual cycle is determined by the exposure to swell and characteristics of the wave field within the region. Local winds have a more identifiable impact on Northern Hemisphere SWARs than on Southern Hemisphere SWARs due to the larger seasonality of Northern Hemisphere winds.

In this work we present a unique set of coincident and collocated high- resolution observations of surface currents and directional properties of surface waves collected from an airborne instrument, the Modular Aerial Sensing System (MASS), collected off the coast of Southern California. High-resolution observations of near surface current profiles and shear are obtained using a new instrument, DoppVis, capable of capturing horizontal spatial current variability down to 128m resolution. This data set provides a unique opportunity to examine how currents at scales ranging from 1-100 km modulate bulk (e.g. significant wave height), directional and spectral properties of surface gravity waves. Such observations are a step toward developing better understanding of the underlying physics of submesoscale processes (e.g. frontogenesis and frontal arrest) and the nature of transitions between mesoscale and submesoscale dynamics.