Applying Software Engineering Metrics to Land Surface Parameterization Schemes

In addition to model validation techniques and intermodel comparison projects, the authors propose the use of software engineering metrics as an additional tool for the enhancement of "quality" in climate models. By discriminating between internal, directly measurable characteristics of structural complexity, and external characteristics, such as maintainability and comprehensibility, a way to benefit climate modeling by the use of easily derivable metrics is explored. As a small illustration, the results of a pilot project are presented. This is a subproject of the Project for Intercomparison of Landsurface Parameterization Schemes in which the authors use some typical structural complexity metrics, namely, for control flow, size, and coupling. Finally, and purely indicatively, the authors compare the results obtained from these metrics with scientists' subjective views of the psychological complexity of the programs.