Energy Exascale Earth System Model (E3SM) Version 2 U-MICH Version

E3SMv2 with modified longwave radiation scheme (ice scattering + realistic surface emissivity) by Prof. Xianglei Huang's group at U-Michigan.

Note: The master branch is the original E3SMv2 model. Please clone the corresponding branches listed below to get access to the modified model.

Contribute Authors

• Yi-Hsuan Chen (yihsuan@umich.edu)
• Xiuhong Chen (xiuchen@umich.edu)
• Xianwen Jing (xianwen@umich.edu)
• Wuyin Lin (wlin@bnl.gov)
• Chongxing Fan (cxfan@umich.edu)

Available Branches

• master: The original E3SMv2 code. The starting point is indeed a version 137 commits behind the master branch.
• cxfan/master/test: The original E3SM code that we started developing on.
• cxfan/UMRad: Our UMRad modification on the radiation scheme.
  • Two/four-stream radiative solver (flag_rtr2)
    • MC6 ice cloud LW optical scheme (flag_mc6)
  • CAM radiation interface change (radiation.F90; flag_emis and flag_scat)
  • Surface emissivity translational layer in CAM and ELM
  • Bug fixes including non-BFB issues. COSP is turned off here to avoid a bug that has been fixed in the later branches.
• cxfan/wuyin-1-1: Our UMRad modification + Wuyin’s 1-1 improvement.
  • The translational layer code has been migrated to a new file: surface_emis_mod.F90. Except for the location change, everything remains intact.
• cxfan/wuyin-1-2: Our UMRad modification + Wuyin’s 1-2 improvement.
  • Additionally, the surface emissivity dataset is read once a month rather than every time step.
    • The emissivity file name can be specified in the namelist, rather than hardcoded in the source.
    • COSP is switched on.
• cxfan/wuyin-2-0: Our UMRad modification + Wuyin’s 2-0 improvement.
  • Additionally, the surface emissivity dataset is remapped to the model grid. The model now directly reads in the remapped dataset instead of doing the nearest match.
  • The emissivity file name can be specified in the namelist, rather than hardcoded in the source.
  • COSP is switched on.
• cxfan/wuyin-1-2.v2: Our UMRad modification + Wuyin’s 1-2 improvement + E3SM official v2 tag.
  • The branch has been merged with the official v2 tag.
• cxfan/wuyin-2-0.v2: Our UMRad modification + Wuyin’s 2-0 improvement + E3SM official v2 tag.
  • The branch has been merged with the official v2 tag.
• In cxfan/wuyin-1-2 and cxfan/wuyin-2-0, the commits of our modification are grouped together, and it is instructive to read the commits in the chronological order.
• In cxfan/wuyin-1-2.v2 and cxfan/wuyin-2-0.v2, the commits of our modification are mixed with other commits from the E3SM team. They are recommended for production uses.

Test Results

The following speed tests are performed on Cori using the L pelayout (101 nodes, 6464 CPUs, 1 thread), and each test produces 6-month climatology.

Model	Description	Wallclock Time	SYPD	Cost (pehrs/yr)
UMRad.v2.LR.hist_full	Xianwen's code with all flags turned on	3:02:38	4.00	38753.37
UMRad.1-2.v2.LR.hist_full	Wuyin's new I/O that reads the emissivity dataset once a month	2:10:02	5.68	27295.19
UMRad.2-0.v2.LR.hist_full	Wuyin's new I/O that reads the remapped emissivity dataset instead of performing nearest matching	1:57:04	6.46	24024.72
master.v2.LR.hist	The master branch of E3SMv2	-	6.07*	25547.67*

• Estimated via a 10-day run, should be a lower bound for SYPD

For more information on the details of the modification, please refer to this repo or contact me directly.

Energy Exascale Earth System Model (E3SM)

E3SM is a state-of-the-art fully coupled model of the Earth's climate including important biogeochemical and cryospheric processes. It is intended to address the most challenging and demanding climate-change research problems and Department of Energy mission needs while efficiently using DOE Leadership Computing Facilities.

DOI: 10.11578/E3SM/dc.20210927.1

Please visit the project website or our Confluence site for further details.

For questions about the model, use Github Discussions

Table of Contents

• Quick Start
• Supported Machines
• Running
• Contributing
• Acknowledge
• License

Quick Start

The Quick Start page includes instructions on obtaining the necessary code and input data for model setup and execution on a supported machine.

Supported Machines

E3SM is a high-performance computing application and generally requires a capable compute cluster to run a scientifically validated case at a useful simulation speed.

To run E3SM, it is recommended that you obtain time on a Supported Machine.

Running

Please refer to Running E3SM for instructions on running the model.

Contributing

Please refer to Contributing for details on our code development process.

Acknowledgement

The Energy Exascale Earth System Model (E3SM) Project should be acknowledged in publications as the origin of the model using these guidelines.

In addition, the software should be cited. For your convenience, the following BibTeX entry is provided.

@misc{e3sm-model,
	title = {{Energy Exascale Earth System Model (E3SM)}},
	author = {{E3SM Project}},
	abstractNote = {{E3SM} is a state-of-the-art fully coupled model of the {E}arth's 
		climate including important biogeochemical and cryospheric processes.},
	howpublished = {[Computer Software] \url{https://dx.doi.org/10.11578/E3SM/dc.20210927.1}},
	url = {https://dx.doi.org/10.11578/E3SM/dc.20210927.1},
	doi = {10.11578/E3SM/dc.20210927.1},
	year = 2021,
	month = sep,
}

License

The E3SM model is available under a BSD 3-clause license. Please see LICENSE for details.