An Overview of the Atmospheric Component of the Energy Exascale Earth System Model

• Published in: Journal of Advances in Modeling Earth Systems
• Main Authors: Rasch, P. J., Xie, S., Ma, P.‐l., Lin, W., Wang, H., Tang, Q., Burrows, S. M., Caldwell, P., Zhang, K., Easter, R. C., Cameron‐smith, P., Singh, B., Wan, H., Golaz, J.‐c., Harrop, B. E., Roesler, E., Bacmeister, J., Larson, V. E., Evans, K. J., Qian, Y., Taylor, M., Leung, L. R., Zhang, Y., Brent, L., Branstetter, M., Hannay, C., Mahajan, S., Mametjanov, A., Neale, R., Richter, J. H., Yoon, J.‐h., Zender, C. S., Bader, D., Flanner, M., Foucar, J. G., Jacob, R., Keen, N., Klein, S. A., Liu, X., Salinger, A.G., Shrivastava, M., Yang, Y.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Wiley Periodicals, Inc. 2019
• Subjects: climate change; Earth system; atmospheric model; climate; climate modeling; general circulation modeling; Geological Sciences; Science; Arctic
• Online Access: http://hdl.handle.net/2027.42/151811; https://doi.org/10.1029/2019MS001629

The Energy Exascale Earth System Model Atmosphere Model version 1, the atmospheric component of the Department of Energy’s Energy Exascale Earth System Model is described. The model began as a fork of the wellâ known Community Atmosphere Model, but it has evolved in new ways, and coding, performance, resolution, physical processes (primarily cloud and aerosols formulations), testing and development procedures now differ significantly. Vertical resolution was increased (from 30 to 72 layers), and the model top extended to 60 km (~0.1 hPa). A simple ozone photochemistry predicts stratospheric ozone, and the model now supports increased and more realistic variability in the upper troposphere and stratosphere. An optional improved treatment of lightâ absorbing particle deposition to snowpack and ice is available, and stronger connections with Earth system biogeochemistry can be used for some science problems. Satellite and groundâ based cloud and aerosol simulators were implemented to facilitate evaluation of clouds, aerosols, and aerosolâ cloud interactions. Higher horizontal and vertical resolution, increased complexity, and more predicted and transported variables have increased the model computational cost and changed the simulations considerably. These changes required development of alternate strategies for tuning and evaluation as it was not feasible to â brute forceâ tune the highâ resolution configurations, so shortâ term hindcasts, perturbed parameter ensemble simulations, and regionally refined simulations provided guidance on tuning and parameterization sensitivity to higher resolution. A brief overview of the model and model climate is provided. Model fidelity has generally improved compared to its predecessors and the CMIP5 generation of climate models.Plain Language SummaryThis study provides an overview of a new computer model of the Earth’s atmosphere that is used as one component of the Department of Energy’s latest Earth system model. The model can be used to help understand past, present, and ...