Illustrated beginner's guide to using netCDF operators (NCO) command line tools

The netCDF (network Common Data Form) file format is increasingly used to store and manage multidimensional scientific data. Although netCDF files offer multiple advanced features and functionality in their own right, workflows that involve netCDF files can be intimidating for new users due to their binary format. There are several methods to manage netCDF file data including via libraries in programming languages such as Fortran or Python. However these methods require knowledge of the programming languages as a prerequisite. Other user-interface applications such as Panoply, NetCDF Explorer, or ArcGIS have functionality to access, view, and in some cases modify or create netCDF files. Another tool to manage netCDF files is the netCDF operators (NCO). NCO is a set of command line tools developed and maintained by the original creators of the netCDF file, the Unidata program at the University Corporation for Atmospheric Research. As such NCO tools are highly optimized and flexible, allowing a myriad of netCDF workflows. This html-based tutorial aims to demystify basic functionalities and syntax of NCO commands that are useful for analysing netCDF scientific data. The tutorial contains multiple examples that focus on scientific data (e.g. climatic measurements or model output) analysis including code snippets, explanations, and figures. Specifically, part 1 covers basic concatenation and averaging of single and ensemble record variables using the ncrcat, ncecat, ncra, and ncea commands respectively. Part 2 builds on part 1 and focuses on basic and advanced uses of the weighted-averaging command ncwa. Examples of other common NCO commands including breif desctiptions on how to download or install the package, and tools for netCDF visualization are also included in the tutorial. Although the tutorial is not in depth, as it does not explicitly cover all the NCO commands nor all of their options, it is a good starting point as many other NCO commands follow similar syntax and conventions.