The deformation module.

This module implements functions to calculate the deformation tensor for data on a C-grid.

New at 0.5

  1. Relocated to subfilter.utils.

New at 0.4

  1. Use of xarray and dask.

Detailed Module Contents

The entire module is documented below.

Created on Mon Aug 2 11:29:37 2021

@author: Peter Clark

subfilter.utils.deformation.deformation(source_dataset, ref_dataset, derived_dataset, options, grid='w', uvw_names=['u', 'v', 'w'])

Compute deformation tensor.

Deformation tensor is defined as {\partial u_{i}}/{\partial {x_j}}.

Parameters

  • source_dataset (NetCDF dataset) – Inout data.

  • ref_dataset (NetCDF dataset) – Input data for input containing reference profiles. Can be None

  • derived_dataset (NetCDF dataset) – Output dataset for derived data.

  • options (dict) – General options e.g. FFT method used.

  • grid (str) – destination grid (Default = ‘w’)

  • uvw_names (list of str) – specific names for u, v, and w fields when differing from MONC default Required to be in this order, otherwise we can change to 3 parameters?

Returns

Array with new dimensions ‘i’ and ‘j’. Saves to derived_dataset if options[‘save_all’].lower() == ‘yes’.

Return type

xarray

@author: Peter Clark

subfilter.utils.deformation.shear(d, no_trace: bool = True)

Compute shear tensor from deformation tensor.

Shear tensor is defined by S_{ij}={\partial u_{i}}/{\partial {x_j}} +{\partial u_{j}}/{\partial {x_i}}.

Parameters

  • d (xarray) – Deformation tensor with dimensions ‘i’ and ‘j’.

  • no_trace (bool, optional) – If true, subtract trace (divergence). The default is True.

Returns

  • S (xarray) – Shear with new dimension ‘i_j’.

  • mod_S_sq (xarray) – Modulus of shear squared. 1/2 S_{ij}S_{ij}

subfilter.utils.deformation.vorticity(d)

Compute vorticity vector from deformation tensor.

vorticity vector is defined as \omega_{k}=({\partial u_{i}}/{\partial {x_j}} -{\partial u_{j}}/{\partial {x_i}}) with kij defined cyclically (i.e. 123, 231, 312).

Parameters

d (xarray) – Deformation tensor with dimensions ‘i’ and ‘j’.

Returns

vorticity – Vorticity with dimension ‘i’.

Return type

xarray