Snapshot of the simulated landfall of an atmospheric river along the west coast of North America on February 11, 2020. Grey tones depict water vapor. Colors indicate precipitation intensity from blue (light rain) to green (very strong precipitation).
The Science
Researchers working on the Energy Exascale Earth System Model (E3SM) project have developed an entirely new global atmosphere model. The model has a resolution 30 times finer than global climate models. This resolution allows scientists to model and study the atmosphere with far more detail than previously possible. A new paper describes the equations that govern the new global atmosphere model and evaluates the model’s first simulation.
The Impact
This new model is a cornerstone of E3SM’s exascale computing strategy. This strategy involves taking full advantage of powerful future computers for improved climate models. Proof of the new model is therefore an important project milestone. The evaluation of the model results validate the E3SM strategy by showing how modeling storms and topography in global-storm resolving scale fixes many longstanding biases in climate modeling.
Summary
Upcoming exascale computers will enable scientists to explicitly resolve deep convection and regional topography in multi-decadal simulations. This ability will dramatically expand the power of climate forecasts. Embracing this upcoming opportunity, E3SM has created a new global atmospheric model designed for the exascale machines planned for Department of Energy (DOE) Leadership Computing Facilities in 2023-2024. This new research introduces the new model, describes its governing equations, and demonstrates that a prototype version faithfully reproduces the current climate. The researchers simulated the period from January 20 to February 28, 2020, with 3-kilometer horizontal resolution globally. This is 30 times finer than the typical resolution for global climate models (GCMs). The new model greatly alleviates many longstanding systematic errors in standard resolution GCMs. For example, the new model improves precipitation modeling in terms of the timing of its diurnal cycle and the distribution of light versus heavy rainfall. The new model also captures the structure of important weather events—such as tropical and extratropical cyclones, atmospheric rivers, and cold air outbreaks—that are poorly captured by typical GCMs. This paper is an important step toward a revolution in DOE climate modeling where simulations of unprecedented detail and realism lead the way to much more accurate climate predictions.
Funding
This research was supported as part of the E3SM project funded by the DOE Office of Science, Office of Biological and Environmental Research. It used resources of the National Energy Research Scientific Computing Center (NERSC), a DOE Office of Science user facility located at Lawrence Berkeley National Laboratory. This research also used resources from the Argonne Leadership Computing Facility at Argonne National Laboratory.
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