Gridmarthe in a nutshell

Warning

This section is under construction !

Objective

gridmarthe allow users to read/write efficiently Marthe Grids (v9, v8, constant_data, etc.) with python, for any MARTHE variable.

With the gridmarthe API, data are stored in a xarray dataset, and can be manage with xarray functions (or numpy). Specific treatments/functions are also provided by gridmarthe.

The package also install different command line tools: ncmart to convert Marthe Grid to netCDF format, martshp to convert in shapefile/geopackage, cleanmgrid to fix marthe grid format.

Tutorials are available in the Grid processing section.

Grid convention

Grids are stored as a 2 dimension matrix, composed of a 1D spatial vector and a time dimension. This means that the spatial domain is flatten in grid, and each point is associated with a index, a x coordinate, a y coordinate, eventually a z coordinate (number of layer in most cases), and dx,dy values.

Still, as Marthe meshes are always parallelepiped, the array stored by gridmarthe does not necessarily follow the ugrid convention. This may be an evolution for future version if required.

The x, and y coordinates are the center of cell. Dx, Dy are the dimension of the cell.