OCEANVAR software for use with NEMO: documentation and user guide

In this document is described the OceanVAR software (a three- dimensional variational data assimilation system, 3dvar) developed at the CMCC for use with the NEMO modeling system and SLA, ARGO, XBT and GLIDER observations [1]. OceanVar software was developed using Fortran90 and it uses the NetCDF library to read the input files provided from NEMO software. This document has the aim to provide a guide for the installation and the use of the OceanVar software. So, here is provided a brief description of the 3dvar model developed, the main steps of the algorithm implemented are shown, and above all how you can use the software is explained: how to install it, what you need to know to install it, where are located the routine, where to find the sources codes, how to edit the Makefile, how to write the input files etc. Regarding the input files we devoted some Sections to show the structure of these file. We provide the schemes you need follow to build the various input files.