In October 2012, Hurricane Sandy struck the northeastern United States around New Jersey and devastated a number of large metropolitan areas, including New York City. However, for all the destruction and chaos it wrought, the storm also allowed researchers to closely monitor a host of environmental and physical phenomena associated with a storm of such magnitude.
Miles et al. report observations of ocean sediment movement off New Jersey’s coast, caused by the storm. Data from an ocean glider equipped with a host of scientific instrumentation and deployed ahead of the storm allowed researchers not only to see how sediment was being redistributed by the hurricane as the storm unfolded but also to compare their real-life observations with forecasts from mathematical models.
The glider used optical and acoustic backscatter—techniques similar to radar in which sound or light is bounced off of surroundings and analyzed upon return—to survey the water for sediment particles of two different sizes (0.4 and 0.1 millimeter) commonly used in models. It observed that both particle sizes got completely suspended in the water column during the 24-hour period of peak storm intensity.
In addition to confirming the models’ predictions, the finding indicates that perhaps unsurprisingly, Hurricane Sandy was seriously stirring up the ocean floor along her path. Certainly, this leads to erosion in some areas, but it also increases sediment deposition in others.
The researchers conclude that after the hurricane made landfall, its energy dipped below the threshold necessary to keep the sediment particles suspended in the water column. But where did all that swirling debris land?
According to the model predictions, Sandy dropped about 3 centimeters of sediment across the continental shelf just north of the Delaware Bay. The team suggests that hurricanes play an important role in redistributing ocean sediment and that gliders can play a valuable role in tracking a storm’s effect on local ecosystems. (Journal of Geophysical Research: Oceans, doi:10.1002/2014JC010474, 2015)
—David Shultz, Freelance Writer
Citation: Shultz, D. (2015), Underwater robot tracked ocean sediment during Hurricane Sandy, Eos, 96, doi:10.1029/2015EO032937. Published on 20 July 2015.