Coherent Set (2 of 2) (IMAGE) American Institute of Physics Caption These two images show that the most "coherent set," the most nondispersive transport time from Sept. 1 to Sept. 14, is in fact the vortex itself over this domain -- demonstrating that the new technique very accurately pinpoints the polar vortex at specific times. Credit American Institute of Physics Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.