Source Modifications

The goal of this chapter is to learn how to modify the CESM source code. These changes are commonly referred to as source modifications and are used when the desired model behavior cannot be achieved through namelist settings alone.

In this chapter, you will learn how to make, build, and test source code changes within a CESM case.

Specifically, this chapter covers:

• Overview – Introduces the workflow for making source modifications and describes the directories and files involved in the process.

• Source Modification Example – Provides a step-by-step example showing how to add a new diagnostic variable to CAM: atmospheric temperature at 750 hPa.

• Exercises – Offers hands-on opportunities to practice modifying CESM source code and rebuilding the model.

By the end of this chapter, you will understand how source modifications are managed within a CESM case and how to safely experiment with changes to the model code.