The Energy Exascale Earth System Model (E3SM) Project is an ongoing, state-of-the-science earth system modeling, simulation, and prediction project that optimizes the use of DOE laboratory resources to meet the science needs of the nation and the mission needs of DOE. In this context, “laboratory resources” include current and future personnel, programs, and facilities. Collectively, they represent a unique combination of proficiencies in science, engineering, leadership computing, and information technologies—the expertise required to construct, maintain, and advance an earth system modeling capability needed by the country and DOE.

• E3SM Website
• E3SM Newsletter
• To subscribe to the E3SM newsletter, listserv@lists.llnl.gov  with email body:  ‘subscribe E3SM-news’.

E3SM Vision and Mission

Over the past three years, E3SM Phase I developed the first version (v1) of the E3SM model. Phase II  expands and extends this work by further exercising the low- and high-resolution versions of v1, adding available improvements and exercising the model with regional refinement over North America for v2. Phase II will also significantly improve model performance, infrastructure, and Earth system capabilities by developing v3-v4 (for use in a Phase III simulation campaign). Phase II will continue to push the envelope in terms of model resolution beyond the current hydrostatic limit in the atmosphere. During this period, the coupled system will run efficiently on the most powerful DOE High-Performance Computational Facility computers. The E3SM project will assert and maintain an international scientific leadership position in the development of Earth system models capable of performing simulations that address the most critical scientific questions for the nation and DOE.

E3SM Science

E3SM’s scientific goals address areas of importance to both climate and earth system research:

1. Water Cycle: The v1 water cycle research and experiments examine the hydrological cycle and its sensitivity to model resolution and radiative forcings. They address the science question, "How will more realistic portrayals of features important to the water cycle (clouds, aerosols, snowpack, river routing, land use) affect simulations of river flow and associated freshwater supplies at the watershed scale?" 
2. Biogeochemistry and Energy: Uptake of CO₂ by land and ocean ecosystems determines how much atmospheric CO₂ concentrations increase due to emissions from combustion and other human activities. In turn, the efficiency of ecosystems in sequestering carbon responds to changes in climate and CO₂ concentration. The v1 biogeochemistry experiment seeks to answer this question: "What are the effects of nitrogen and phosphorous on climate-biogeochemistry interactions, and how sensitive are these interactions to model structural uncertainty?"
3. Cryosphere-Ocean System: With an eye towards eventually bounding Antarctica’s contribution to future sea-level rise over the next 50 years, Phase I simulations and analysis have focused on exploring the factors influencing submarine melt rates of Antarctic ice shelves and the impacts of related freshwater fluxes on the Antarctic-proximal, Southern Ocean circulation. The cryosphere focus within E3SM addresses the scientific question: "What are the impacts of ocean-ice shelf interactions on the melting of the Antarctic Ice Sheet, the global climate, and sea-level rise?"
4. Performance: During the first phase of the E3SM project, much of the focus needed to be on the creation and integration of a new model. The transition from version 0 (v0) to version 1 (v1) increased the computational cost by approximately a factor of 4 through a combination of increased vertical resolution, increased number of tracers, more expensive parameterizations and the introduction of entire new ocean and ice components with more accurate (but more expensive) numerics. Despite the increased expense, work by the performance team limited the impact on throughput to only 30% as measured on Titan and total cost to the allocation only increased by a factor of 2.3. Effectively, this meant a performance improvement of ~2x over this first phase of the project. 

For more information, visit the E3SM website.