A research consortium formed after the Deepwater Horizon oil spill has deployed more than 300 water drifters near the rig’s explosion site to study surface currents in the Gulf of Mexico. Known as the Grand Lagrangian deployment, it is the largest of its kind in history.

By logging the drifters’ locations as they move, scientists have gained insights into the effects sea currents have on the transport of crude oil. The data, collection of which began in July 2012, will help emergency planning and improve forecasts of the pollutant’s movement in future oceanic disasters.

The Consortium for Advanced Research on Transport of Hydrocarbon in the Environment (CARTHE) won funding for the project from the Gulf of Mexico Research Initiative. The research initiative was founded through an agreement between the Gulf of Mexico Alliance and BP to provide USD500 million in funding for independent scientific research related to the Deepwater Horizon incident over the course of 10 years.

The project began with help from the U.S. Coast Guard, which has routinely used data from drifters in search and rescue missions. The Coast Guard agreed to drop a few drifters into the Gulf in exchange for use of the experiment’s data when it was fully up and running.

To start, four drifters were deployed by air to get a sense of circulation before the mass deployment, followed by 24 around Deepwater Horizon and about 90 each day at different sites. Most of the deployments took place in three days. Data were made available immediately to the U.S. Coast Guard. They used it the whole time for test missions and whenever Hurricane Isaac hit. They saw ours and needed to deploy fewer of their own.

In all, 317 drifters were placed into the Gulf, each one about three feet tall with floats and support screens that keep each GPS unit stable and vertical. A typical research project would only need 10 to 20 drifters.

The GPS transmitters relay the coordinates of each drifter to a satellite, which provides updates to researchers every five minutes. That transmission frequency made it possible for them to find more variations between data points.

A part from the rotation of the Earth causing oscillations and the presence of many rigs, heat in the Gulf also affects the water currents there and is another consideration to take into account. The Florida Straits were a factor, strong currents which only took a few drifters out of the Gulf.

Improving forecast models can be used by the Coast Guard and emergency responders in future disasters.

On average, there is one oil spill per year in the Gulf. Improved forecasting models could help contain them better. The Naval Research Laboratory will likely use the data to strengthen its models.

When a drifter goes offline – in average two a day, fishermen find them and send them back to CARTHE. This organisation is working on a prototype drifter that is biologically degradable and about the size of a sushi box. Ten prototypes were tested in the deployment.

When transmissions end, CARTHE will begin analysing the more than five million data points that have been collected. (spill-international, Edited by Topco)