Overview ======== **pySVA** is a Python-based open-source toolbox for computing terms in a salinity variance budget on unstructured mesh model output. It applies to model output from models with unstructured, staggered C-grid meshes, particularly from models like `D-FLOW Flexible Mesh `_. The toolbox implements the salinity variance budget framework of `Burchard et al. (2008) `_ and `Li et al. (2018) `_, which decomposes tracer variance changes into contributions from advection, straining/mixing, and dissipation. This approach enables quantification of both physical and numerical mixing processes in hydrodynamic models. It is available as open source on `Github `_ under the MIT license. Purpose ------- The pySVA toolbox enables quantification of physical and numerical mixing processes in hydrodynamic models by decomposing changes in tracer variance into contributions from: - **Advection**: Transport of variance by mean flow - **Straining**: Variance production/destruction due to vertical mixing and shear - **Dissipation**: Variance reduction due to diffusion (turbulent mixing) This approach provides insight into the mechanisms responsible for spatial patterns of stratification in coastal and estuarine systems. Key Features ------------ - Handles multiple input formats: NetCDF files, xarray Datasets, and xugrid UgridDatasets - Automatically extracts grid topology and coordinate systems - Provides cached geometric properties for efficient computation - Implements the variance budget framework of Burchard et al. (2008) and Li et al. (2018) Status ------ ⚠️ **Note:** This package is currently in limited maintenance mode. Issues can still be opened, but fixes might take longer.