Visualizing Science

The Global Conveyor Belt

How polynyas drive global ocean currents that moderate temperatures across the planet

The Earth’s climate is an extremely large and complex system. Regional climate events such as droughts, storms, floods, and polynyas, openings in sea ice, affect the climate in significant ways.

And yet these local events have far-reaching effects. Conditions in North Africa give rise to storms that cross the Atlantic and strike U.S. shores as hurricanes. El Niño and La Niña in the Pacific have a major impact on the weather in North America.

Oceanographers are using global climate models, some of the largest computations performed, to study the conditions under which large polynyas form and whether climate change is impacting their frequency.

“Winds drive circulation in the upper part of the ocean, but at the bottom of the ocean floor, there is another complex system of currents driven by changes in density."
Prajvala Kurtakoti, Oceanographer, Johns Hopkins University

“Polynyas are ice-free areas in the winter sea ice pack that are associated with deep convection, potentially contributing to the formation of bottom water,” said Prajvala Kurtakoti, an oceanographer at Johns Hopkins University. 

“Winds drive circulation in the upper part of the ocean, but at the bottom of the ocean floor, there is another complex system of currents driven by changes in density. This ‘global conveyor belt’ is a system of heat distribution which contains both the surface and the deep ocean.”

Kurtakoti’s analyses show that the moderate vertical seawater cycle, almost 2,000 meters high, increases turbulence and creates an opening in the ice. If the wind and water temperatures are conducive, the opening will expand to create a polynya the size of Colorado. Her work on Maud Rise Polynyas supports the premise that ocean floor topography playa role in polynya formation.

“We’re not looking at observations—we’re looking at output from one of the world’s premier fully coupled Earth system models running on one of the world’s fastest supercomputers.”

Visualization Behind the Image Stills

This visualization is the result of processing large time-dependent datasets that result from the Department of Energy’s E3SM coupled ocean, sea, ice, and atmosphere models. They were produced using the Paraview visualization tool, augmented by custom components to prepare the data for 3D visualization and to interpolate between time steps to produce particle traces in the atmosphere over time. The visualization was created by TACC research scientists on the Stampede2 supercomputer. 


Credit: Mark Petersen, LeAnn Conlon, Prajvala Kurtakoti, Linnea Palstom, John Patchett, Andrew Roberts at Los Alamos National Lab. Francesca Samsel, Greg Abram, Stephanie Zeller at TACC.