MOM is instrumented with a variety of diagnostic options. Some are useful for diagnosing model problems while others are aimed towards providing information to help resolve questions of a more scientific nature. All are independent of each other and each is activated with its own option at compile time. For added flexibility, each diagnostic has an associated interval, control, and possibly an averaging period variable which are input through namelist. To see all namelist variables, refer to Section 14.4.
When not enabled, a diagnostic requires neither memory nor computational time. When enabled, some require large amounts of memory, disk, or cpu time so it is important to use them cautiously with specific goals in mind. The amount of time generally depends on the particular configuration of MOM, which diagnostics are enabled, the interval between diagnostic output, and the averaging period (if applicable). An assessment of the computational time38.1 can easily be made by enabling the required diagnostics along with option timing38.2 in a short model execution.
The purpose of this chapter is to introduce some general ideas about the design of diagnostics in MOM. Subsequent chapters describe the different physical and numerical analysis options.