Pre-exascale computing infrastructure, like Summit, runs the powerful E3SM model while the next-generation exascale computers are being built. (Exascale refers to a computing system capable of carrying out a billion billion (109 x 109 = 1018) calculations per second.) Image credit: Oak Ridge National Laboratory

A new Earth System Model (ESM) unveiled today will have weather scale resolution and use advanced computers to simulate aspects of Earth’s variability and decadal changes expected to impact the U.S. energy sector in coming years.

After four years of development, the Energy Exascale Earth System Model (E3SM) will be released to the broader scientific community today. The E3SM project is supported by the Department of Energy’s Office of Science in the Biological and Environmental Research Office. The E3SM release will include model code and documentation, as well as output from an initial set of benchmark simulations.

Working in collaboration with scientists from multiple DOE laboratories, experts from the Earth and Environmental Sciences Area at Berkeley Lab co-led the effort to improve the land component of the earth system model. This model component predicts how factors like soil biogeochemistry, plant processes, energy use, drought, and heat affect, for example, water availability and the amount of soil carbon released to the atmosphere as carbon dioxide over annual to centennial time scales.

The Earth, with its myriad interactions of atmosphere, oceans, land, and ice components, presents an extraordinarily complex system for investigation. ESM simulations involve solving approximations of physical, chemical, and biological governing equations at resolutions that are as fine in scale as computing resources will allow.

Senior Scientists Bill Riley and Bill Collins led the Berkeley Lab E3SM project team focused on developing improved representations of land processes, such as soil biogeochemistry and the interactions between soil and plant processes within the new ESM.

“Enhanced computing and new process understanding has enabled our group to dramatically improve the mechanistic representation of terrestrial biogeochemistry, hydrology, and plant processes within the land component of E3SM,” said Riley. “These more realistic representations will enable more-reliable predictions of terrestrial processes than previous models.”

The E3SM project will reliably simulate aspects of earth system variability and project decadal changes that will critically impact the U.S. energy sector in the near future. These critical factors include a) regional air and water temperatures, which can affect energy production and CO2 exchanges with the atmosphere; b) water availability, which affects power plant operations; c) extreme water-cycle events (e.g., floods and droughts), which impact infrastructure and bio-energy; and d) sea-level rise and coastal flooding which threaten coastal infrastructure.

The goal of the project is to develop an ESM that can take advantage of next-generation computing technologies. Meeting this goal will require advances on three frontiers: 1) better resolving earth system processes through a strategic combination of developing new processes in the model, increased model resolution, and enhanced computational performance; 2) representing more realistically the two-way interactions between human activities and natural processes, especially where these interactions affect U.S. energy needs; and 3) ensemble modeling to quantify uncertainty of model simulations and projections.

“The quality and quantity of observations really makes us constrain the models,” said David Bader, LLNL scientist and lead of the E3SM project. “With the new system, we’ll be able to more realistically simulate the present, which gives us more confidence to simulate the future.”

Simulating atmospheric and oceanic fluid dynamics with fine spatial resolution is especially challenging for ESMs. The E3SM project is positioned on the forefront of this research challenge, acting on behalf of an international ESM effort. Increasing the number of earth-system days simulated per day of computing time is a prerequisite for achieving the E3SM project goal. It also is important for E3SM to effectively use the diverse computer architectures that the DOE Advanced Scientific Computing Research (ASCR) Office procures to be prepared for the uncertain future of next-generation machines. A long-term aim of the E3SM project is to use exascale machines to be procured over the next five years. The development of the E3SM is proceeding in tandem with the Exascale Computing Initiative (ECI). (An exascale refers to a computing system capable of carrying out a billion billion (109 x 109 = 1018) calculations per second. This represents a thousand-fold increase in performance over that of the most advanced computers from a decade ago),

“This model adds a much more complete representation between interactions of the energy system and the earth system,” Bader said. “The increase in computing power allows us to add more detail to processes and interactions that results in more accurate and useful simulations than previous models.”

To address the diverse critical factors impacting the U.S. energy sector, the E3SM project is dedicated to answering three overarching scientific questions that drive its numerical experimentation initiatives:

  • Water Cycle: How does the hydrological cycle interact with the rest of the human-Earth system on local to global scales to determine water availability and water cycle extremes?
  • Biogeochemistry: How do biogeochemical cycles interact with other Earth system components to influence the energy sector?
  • Cryosphere Systems: How do rapid changes in cryosphere (continental and ocean ice) systems evolve with the Earth system, and contribute to sea-level rise and increased coastal vulnerability?

In E3SM, all model components (atmosphere, ocean, land, ice) are able to employ variable resolution to focus computing power on fine-scale processes in regions of particular interest. This is implemented using advanced mesh-designs that smoothly taper the grid-scale from the coarser outer region to the more refined region.

The E3SM project includes more than 100 scientists and software engineers at multiple DOE Laboratories as well as several universities; the DOE national laboratories include Argonne, Brookhaven, Lawrence Livermore, Lawrence Berkeley, Los Alamos, Oak Ridge, Pacific Northwest, and Sandia. In recognition of unifying the DOE earth system modeling community to perform high-resolution coupled simulations, the E3SM executive committee was awarded the Secretary of Energy’s Achievement Award in 2015.

In addition, the E3SM project also benefits from-DOE programmatic collaborations including the Exascale Computing Project (ECP) and programs in Scientific Discovery through Advanced Computing (SciDAC), Climate Model Development and Validation (CMDV), Atmospheric Radiation Measurement (ARM), Program for Climate Model Diagnosis and Intercomparison (PCMDI), International Land Model Benchmarking Project (iLAMB), Community Earth System Model (CESM) and Next Generation Ecosystem Experiments (NGEE) for the Arctic and the Tropics.

For information, visit the E3SM website.