Study Shows that Floating Bamboo Plates Capture Strength of Small-Scale Ocean Currents
January 27, 2020
Researchers optically tracked 600 biodegradable bamboo plates floating in the Gulf of Mexico for 2.5 hours to better understand how small-scale currents (scales of minutes and meters) affect surface dispersion. Ten minutes after releasing the plates onto the water’s surface, the plates collected in narrow parallel convergence zones (known as windrows and sometimes referred to as streaks) as a result of Langmuir circulation (counter-rotating vortices aligned with wind direction). The spacing between the streaks was initially 15 meters apart, then widened to 40 meters after 20 minutes, and then slowly widened to 50 meters over 60 minutes. Comparison of statistics from nearby ocean drifters and the floating bamboo plates suggest that the plates provide a better indication of the strength of small-scale currents than do drifters. The results point to the important role that small-scale motions play in organizing floating material, such spilled oil, and is an important component in ocean transport predictions, which can inform spill response plans. The results also provide insight into how energy is redistributed in the ocean through currents at various scales.
The authors published their findings in the Journal of Physical Oceanography: Small-scale dispersion in the presence of Langmuir circulation.
Ocean currents at many scales cause floating material (i.e. plastics, wreckage debris, oil) to move. Historically, there has been more research about larger-scale circulations, which are detectable by satellite imagery, than smaller-scale circulations, which are difficult to study because of their fast and short-lived action.