Implement checks in CTSM namelist build

Oct 13, 2025 by wbrum.org 15 views

Resolving the Issue: Concurrent Use of SP and ST3 Modes in FATES

The FATES (Functionally Asynchronous Trunk and Extensions of the Community Land Model) model is a crucial component of the Community Earth System Model (CESM), used for simulating the Earth's climate system. In this context, the use of specific control variables, such as use_fates_sp and use_fates_ed_st3, is essential for configuring the model's behavior. However, a recent observation has revealed that these variables can be enabled simultaneously, which is not intended according to the model's design. This article aims to investigate the issue, provide relevant information, and propose potential solutions.

A recent experiment has demonstrated that it is possible to activate both use_fates_sp and use_fates_ed_st3 modes simultaneously, which is contrary to the expectations of the model developers, @adrifoster and @glemieux. This unexpected behavior has significant implications for the model's performance and accuracy. To address this issue, a check will be added to the namelist build in the Community Terrestrial System Model (CTSM) to prevent this concurrent use. However, it is also essential to implement similar checks within the FATES Fortran code to ensure the model's integrity.

# No relevant log output is provided in this case

The FATES tag used in this experiment is sci.1.81.0_api.37.1.0, which indicates the specific version of the FATES model employed.

The host land model tag is ctsm5.3.030, which represents the version of the Community Terrestrial System Model used in conjunction with FATES.

The machine used for this experiment is derecho, which is a specific type of computing hardware.

No other supported machine name is provided in this context.

No additional context is available for this issue.

To resolve this issue, the following steps can be taken:

Implement checks in CTSM namelist build: A check will be added to the namelist build in CTSM to prevent the concurrent use of use_fates_sp and use_fates_ed_st3 modes.
Integrate checks in FATES Fortran code: Similar checks will be implemented within the FATES Fortran code to ensure the model's integrity and prevent this unexpected behavior.
Review and update control variable checking: A thorough review of the control variable checking mechanism will be conducted to identify potential issues and implement necessary updates.

The concurrent use of use_fates_sp and use_fates_ed_st3 modes in FATES is not intended according to the model's design. To address this issue, checks will be implemented in both the CTSM namelist build and the FATES Fortran code. Additionally, a review of the control variable checking mechanism will be conducted to ensure the model's integrity and prevent similar issues in the future.
Frequently Asked Questions: Concurrent Use of SP and ST3 Modes in FATES

The FATES (Functionally Asynchronous Trunk and Extensions of the Community Land Model) model is a crucial component of the Community Earth System Model (CESM), used for simulating the Earth's climate system. In this context, the use of specific control variables, such as use_fates_sp and use_fates_ed_st3, is essential for configuring the model's behavior. However, a recent observation has revealed that these variables can be enabled simultaneously, which is not intended according to the model's design. This article aims to provide answers to frequently asked questions related to this issue.

A: The use_fates_sp control variable is used to enable the Single-Process (SP) mode in FATES, which allows the model to run on a single processor. The use_fates_ed_st3 control variable is used to enable the ST3 mode, which is a specific configuration of the model.

A: The concurrent use of these modes is not intended because it can lead to unexpected behavior and potential errors in the model's output. The FATES model is designed to operate in a specific way, and enabling both modes simultaneously can disrupt this behavior.

A: The implications of using both modes simultaneously can be significant. It can lead to incorrect results, errors, and potential crashes of the model. Additionally, it can also affect the model's performance and accuracy.

A: To prevent the concurrent use of these modes, you can implement checks in the CTSM namelist build and the FATES Fortran code. This will ensure that the model is configured correctly and prevent unexpected behavior.

A: The potential solutions to this issue include:

Implement checks in CTSM namelist build: A check will be added to the namelist build in CTSM to prevent the concurrent use of use_fates_sp and use_fates_ed_st3 modes.
Integrate checks in FATES Fortran code: Similar checks will be implemented within the FATES Fortran code to ensure the model's integrity and prevent this unexpected behavior.
Review and update control variable checking: A thorough review of the control variable checking mechanism will be conducted to identify potential issues and implement necessary updates.

A: If you encounter any issues related to the concurrent use of these modes, you can report them to the FATES development team. They will investigate the issue and provide a solution to prevent similar problems in the future.