Objectives & Approach

OceanOSSE is an open-source Python package developed as part of the Explaining and Predicting the Ocean Conveyor (EPOC) project.

Objectives

• Develop a next generation observing system experiment tool to evaluate an AMOC observing system for the whole Atlantic.
• Simulating Argo float-style observations, satellite altimetry and gliders, as well as traditional mooring measurements.
• Build a modular open-source tool which can be used to produce gridded model outputs sampled analogously to ocean observing platforms.
• Initial set of possible AMOC observing designs including (1) only Argo and altimetry, (2) blended moorings with Argo and altimetry.

Approach

• Develop an open-source, Python package hosted in the AMOCcommunity GitHub organisation for performing Observation System Simulation Experiments (OSSEs) in ocean general circulation models.

• We will focus on developing a command-line Python tool, which will ingest gridded ocean model output files (e.g., conservative temperature & absolute salinity), subsample them in a way that is representative of a gridded product generated from a user-specified observing platform (e.g., Argo profiling floats), and write these subsampled fields to one or more output files (e.g., netCDF).

Initial Scope

Given our short timescale, we will focus our development on the following:

• Creating a reliable & reproducible data pipeline invoked from the command line, which is written in a modular, object-oriented style.

• Testing with NEMO ocean model outputs (NOC Near-Present Day conservative temperature and absolute salinity fields provided defined on their original NEMO model grid).

• Delivering an ArgoSampler() class to perform probabilistic subsampling of NEMO model temperature and salinity fields akin to historical Argo sampling.

• Representing instrument error by adding uncertainty to subsampled fields.

• Creating multiple writers to save subsampled fields to local Zarr stores or netCDF files only.

Subject to acquiring more development time, the modular code base developed in the initial phase will serve as the foundation for including mooring and satellite samplers and adding more complex error models. If further time is not made available, the package delivered in the initial phase should be sufficient for development to continue through the open-source community.