The impact of storm-induced coastal trapped waves on the transport of marine debris using high-frequency radar data

The intensity, frequency, and duration of North Atlantic hurricanes have increased since the early 1980s. Every year these storms impact the Mid-Atlantic Bight (MAB), a region that includes the coastline with the highest US coastal population density, important commercial and naval ports, and commercial and recreational fisheries. The interaction between the storms and the surface currents, including tides and coastal trapped waves (CTWs), have a large economic and destructive impact as well as great implications on marine debris transport before, during, and after storms. The effect of storms on CTWs is the least understood of these interactions. Observations of CTWs from high-frequency radar (HFR) SeaSonde data indicate typical surface velocity amplitudes of 10-20 cm s
^-1
, while maximum velocities can reach as high as 100 cm s
^-1
during strong storms. This suggests that storm-induced CTWs are capable of transporting marine debris farther than typical, non-storm conditions. Focusing on 2012 Hurricane Sandy, which had a major impact in the MAB, the study area is seeded with 100 artificial Lagrangian particles just before Hurricane Sandy made landfall in New Jersey and we calculate their trajectories over five days using observed HFR velocities. The distance traveled and particle paths for full velocity are compared to a CTW-only velocity case during Hurricane Sandy, as well as for a five day non-storm period. In all cases, particles are transported farther under Hurricane Sandy storm conditions than non-storm conditions, with percentage increases between 150-250 %. CTWs have a larger contribution to the total distance traveled using full velocity under storm conditions (47 %) than non-storm conditions (33 %) although CTW increases in distance traveled is directly proportional to increases in wind strength. Furthermore, particle trajectories suggest estuaries disrupt theoretical CTW propagation patterns.