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B-ISICLES (Berkeley Ice Sheet Initiative for Climate at Extreme Scales) Project to Improve Accuracy of Ice Sheet Models

October 30, 2009

Contacts: Linda Vu, lvu@lbl.gov, 510-495-2402

B-ISICLES

One of the most-cited examples of global climate change is retreating ice sheets in Antarctica and Greenland. But the detail of how fast they are melting is a mystery that may be solved with a new generation of computer simulations.

Current computer models can only provide very crude representations of important physical processes like glacier surges, iceberg calving and grounding-line migration. But this is all about to change now that researchers from the Lawrence Berkeley National Laboratory's (Berkeley Lab) Computational Research Division (CRD) and Los Alamos National Laboratory are collaborating to develop parallel adaptive mesh refinement techniques for the Community Ice Sheet Modeling code known as GLIMMER-CISM. These algorithms will allow researchers to model points of interest, like the retreating edges of ice sheets, at unprecedented resolution. With more accurate models, they will be better able to make more accurate predictions about how ice sheet melting is contributing to other phenomena like the rise in global sea level.

"The computational cost of modeling an ice sheet the size of Antarctica at 1 kilometer resolution uniformly is very expensive because the area is so large and the codes do not scale linearly. However, it may be unnecessary to have high resolution everywhere because some areas of the ice sheet, like the edges, change drastically, while others parts may change only slightly over longer periods of time," says Esmond Ng of CRD, the principal investigator of the project.

He says that incorporating adaptive mesh refinement (AMR) techniques into the GLIMMER-CISM code will save a significant amount of computing resources by allowing researchers to create higher resolution models only at the points of interest, which in turn will enable them to make more accurate predictions about the dynamics of ice sheets and the rise in global sea levels. The Berkeley Lab team will also implement auto-tuning techniques to reduce the amount of compute time required to run an ice sheet model.

"All these areas of research are taking advantage of the unique applied mathematics and computer science expertise available at the Berkeley Lab," says Ng. "These include extensive development of AMR, experience in auto-tuning and climate modeling."

The GLIMMER–CISM code is currently being developed by researchers at Los Alamos National Laboratory and the University of Montana and builds on GLIMMER, a state-of-the-art serial code developed at the University of Bristol for ice sheet modeling. The GLIMMER-CISM code will be used to model ice sheet melting for the Intergovernmental Panel on Climate Change's Fifth Assessment Report, which will be publicly released in 2013.

The Department of Energy's Office of Advanced Scientific Computing Research (ASCR) is supporting CRD's role in the GLIMMER-CISM code development through the Ice Sheet Initiative for Climate at Extreme Scale (ISICLES). The Berkeley-ISICLES (BISICLES) project includes Xioaye Li (Scientific Computing Group), Daniel Martin (Applied Numerical Algorithms Group), and Samuel Williams (Future Technologies Group) in CRD, as well as Woo-Sun Yang in NERSC.


About Computing Sciences at Berkeley Lab

The Lawrence Berkeley National Laboratory (Berkeley Lab) Computing Sciences organization provides the computing and networking resources and expertise critical to advancing the Department of Energy's research missions: developing new energy sources, improving energy efficiency, developing new materials and increasing our understanding of ourselves, our world and our universe.

ESnet, the Energy Sciences Network, provides the high-bandwidth, reliable connections that link scientists at 40 DOE research sites to each other and to experimental facilities and supercomputing centers around the country. The National Energy Research Scientific Computing Center (NERSC) powers the discoveries of 6,000 scientists at national laboratories and universities, including those at Berkeley Lab's Computational Research Division (CRD). CRD conducts research and development in mathematical modeling and simulation, algorithm design, data storage, management and analysis, computer system architecture and high-performance software implementation. NERSC and ESnet are DOE Office of Science User Facilities.

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