Getting Beneath the Tip of the Iceberg

Prototype simulation of ice sheet flow in Antarctica on the Stampede supercomputer. The image shows the resulting surface ice velocity corresponding to an assumed friction at the base of the ice sheet. Stampede is critical for enabling the solution of the so-called inverse problem, in which researchers determine uncertain parameters (including the friction at the base of the ice sheet) so that the model is consistent with observed surface flow velocities. Such inverse solutions require numerous forward model solutions. 

Research by Omar Ghattas, the John A. and Katherine G. Jackson Chair in Computational Geosciences.

The accelerating flow of ice streams from Antarctica has the potential to raise sea levels significantly. Omar Ghattas‘ team at The University of Texas at Austin has been using the Stampede supercomputer to better understand and represent the flow of ice from Antarctica into the sea using detailed numerical models.

The problem: Antarctica’s ice rises thousands of feet above the ground, and it’s unclear what lies underneath. Stampede will help the scientists infer the uncertain conditions at the base of Antarctica’s ice by using modern inverse modeling methods. Using a high-fidelity ice flow model developed by Ph.D. student Tobin Isaac, thousands of high-resolution continental-scale simulations are being run on Stampede.

Each simulation fine-tunes the unknown parameters the friction and other parameters at the base of the ice and hones the model so it better reproduces the observed ice flow on the top surface of the ice. Problems of this kind can be solved only on supercomputing systems like Stampede.

“How often does a scientist get an instrument that’s 50 times as powerful as the one it replaces?” said Ghattas, the John A. and Katherine G. Jackson Chair in Computational Geosciences. “It’s a massive step.”