# 1. Preface¶

### 1.1.1. Foreword¶

This user’s and developer’s guide consists of parts targeting two overlapping categories of scientists working with the Earth System Model Evaluation Tool (ESMValTool):

1. Part A: User’s Guide (Part users_guide): this part gives an introduction to the ESMValTool including installation, running the ESMValTool, and available user settings of existing diagnostics and performance metrics. The target group would typically consist of scientists mostly interested in running the ESMValTool as provided either on CMIP model simulations or on simulations performed with other Earth system models, and on observations. An overview on the available diagnostics and metrics packages including a description of the user settings and example plots can be found in Annex C (part annex_c).
2. Part B: Developer’s Guide (Part developers_guide): this part gives additional technical details on the ESMValTool not necessarily needed to apply the ESMValTool as well as an introduction to implementing new variables and new diagnostics. This part is mostly intended for scientists interested in technical details as well as in contributing to the development of the ESMValTool by adding new nameslists and code for additional diagnostics or performance metrics.

For the developer’s guide, it is assumed that the user/developer is already familiar with the ESMValTool framework introduced in the user’s guide.

Please report problems and bugs to the ESMValTool Core Development Team (see Section 3.2 and http://www.esmvaltool.org/). Thank you!

### 1.1.2. ESMValTool website¶

The ESMValTool website is http://www.esmvaltool.org/

### 1.1.3. Main reference¶

The main reference paper for the ESMValTool is:

Eyring, V., Righi, M., Lauer, A., Evaldsson, M., Wenzel, S., Jones, C., Anav, A., Andrews, O., Cionni, I., Davin, E. L., Deser, C., Ehbrecht, C., Friedlingstein, P., Gleckler, P., Gottschaldt, K.-D., Hagemann, S., Juckes, M., Kindermann, S., Krasting, J., Kunert, D., Levine, R., Loew, A., Mäkelä, J., Martin, G., Mason, E., Phillips, A. S., Read, S., Rio, C., Roehrig, R., Senftleben, D., Sterl, A., van Ulft, L. H., Walton, J., Wang, S., and Williams, K. D.: ESMValTool (v1.0) – a community diagnostic and performance metrics tool for routine evaluation of Earth system models in CMIP, Geosci. Model Dev., 9, 1747-1802, doi: 10.5194/gmd-9-1747-2016, 2016.