Science for Everyone

Building Passive Drifters to Monitor Ocean Currents

This year the Eastern Maine Skippers Program students had a chance to build passive drifters with the help of Jim Manning (NOAA) and Cassie Stymiest (NERACOOS). Deploying passive drifters enables researchers to get a better sense of broad current patterns in different parts of the ocean, which is relevant to plankton researchers, teams reacting to oil spills, search and rescue teams, and other oceanographers. 

 Passive Drifter track lines from drifters that are currently pinging out GPS locations

Passive Drifter track lines from drifters that are currently pinging out GPS locations

There are several examples where knowledge of currents from passive drifter data enabled teams to react and mitigate accidents. One significant incident occurred in March of 2011, when the Hooksett Wastewater Treatment Plant (Hooksett, NH) accidentally released several million small gridded plastic disks into the Merrimack River. These disks subsequently washed up along the coast of New Hampshire, Massachusetts, and Southern Maine. When the incident occurred, New Hampshire was able to ask for a model from the data collected by previous passive drifters to predict where the disks would end up. 

Another accidental passive drifter story happened in May of 1990 when 61,000 Nike shoes were released from a shipping container in the North Pacific. This was the largest (albeit accidental) release of drifters, and oceanographers were actually able to validate some of the models by looking at the data from where shoes were washing up. 

One of the reasons it is helpful to keep building, deploying, and tracking drifters from different locations is to add more data to oceanographic models. Although individual drifter paths at first glance seem to have a lot of variability, by averaging their collective movements scientists can gain a more accurate understanding of oceanographic patterns. Our ocean circulation is not fixed, and especially in the context of a changing climate it is important to see how the oceans are responding to warming waters and different wind patterns. 

Building passive drifters is simple and fun! The following are the main assembly steps that the skippers worked on during this workshop:

  1. Cutting and gluing the canvas sails
  2. Attaching grommets to the sails
  3. Assembling the central metal mast
  4. Assembling the mount to hold the GPS transmitter

The final step will be for students to attach the GPS transmitters to their drifters and deploying them so we can track their movements in Penobscot Bay!

We are also looking forward to helping out the drifter dataset by deploying a passive drifter during our Marine Biology program on Hurricane Island! Stay tuned! Want to set up and deploy your own passive drifter? Check out StudentDrifters.org

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