Citation
Frederico Falcini, Douglas J. Jerolmack, and Bruno Buongiorno Nardelli, Mississippi River and Sea Surface Height Effects on Oil Slick Migration, PLoS ONE 7(4): e36037, doi: 10.1371/journal.pone.0036037 (27 April 2012)
Contrasting water and oil densities explain how water mounding fended oil away from Louisiana’s Mississippi River Delta shores
From the University of Pennsylvania’s press release:
Using publicly available datasets, their study reveals that the force of the Mississippi River emptying into the Gulf of Mexico created mounds of freshwater which pushed the oil slick off shore.
“The idea is that, if the water surface is tilting a little bit, then maybe the oil will move downhill, sort of like a ball on a plate. If you tilt the plate, the ball will roll one way and then another,” [co-author Douglas] Jerolmack said.
“Surprisingly no one had really investigated the effect that the tilting of the water surface can have on the migration of oil.”
© 2012 Penn News, A Push From the Mississippi Kept Deepwater Horizon Oil Slick Off Shore, Penn Research Shows, University of Pennsylvania (10 May 2012) (paragraph split)
Shared data made this research both possible and necessary
During the Deepwater Horizon oil spill, the National Oceanic and Atmospheric Administration produced aerial images of the oil’s movement in the Gulf of Mexico. NOAA tried to forecast where the spill would go by using computer models of ocean currents.
These models proved to be unreliable. The oil’s movements were being affected by more than just oceanic and wind currents.
To find out what was going on, Jerolmack’s group looked at sea-surface levels that had been recorded in real time by the Colorado Center for Astrodynamics Research. (These are calculated by radar from the Ocean Surface Topography Mission’s Jason-2 satellite.)
The research team had to separate the land surface’s confounding effect from the raw data. Once done, they recognized that the Gulf of Mexico exhibited water mounds and valleys, where the water surface was higher in some areas and lower between them.
The Delta “bump”
One obvious bump elevated the sea surface at the Mississippi Delta. This was apparently due to the river’s annual spring flood, which delivers a large volume of fresh water into the Gulf:
This powerful discharge of fresh water mounded on top of the denser salt water of the Gulf.
The resulting bulge, which was approximately 10 centimeters higher than the surrounding ocean and 50-100 kilometers in diameter, was positioned so that oil from the Deepwater Horizon drilling rig ran “downhill” and away from the coast.
© 2012 Penn News, A Push From the Mississippi Kept Deepwater Horizon Oil Slick Off Shore, Penn Research Shows, University of Pennsylvania (10 May 2012) (paragraph split)
Jerolmack added that mounds can only form when the river discharge is high and the ocean is calm. When the spring flood ended, the oil spill began moving landward again.
A computer model of 2-layer liquids confirmed the team’s interpretations.
The moral? — Shared data provides unforeseen and useful findings
Which is why the increasing push for proprietary-based restrictions on the movement of scientific data is harmful. And government research and data collection remain so integral to the nation’s science base.
Tagged: BP, Bruno Buongiorno Nardelli, Colorado Center for Astrodynamics Research, Deepwater Horizon, delta, Douglas J. Jerolmack, Frederico Falcini, fresh water, Gulf of Mexico, Jason-2, Mississippi River, National Oceanic and Atmospheric Administration, Ocean Surface Topography Mission, oil slick, salt water, sea surface height