improver.generate_ancillaries.generate_ancillary module

Module containing ancillary generation utilities for Improver

class improver.generate_ancillaries.generate_ancillary.CorrectLandSeaMask[source]

Bases: improver.BasePlugin

Round landsea mask to binary values

Corrects interpolated land sea masks to boolean values of False [sea] and True [land].

_abc_cache = <_weakrefset.WeakSet object>
_abc_negative_cache = <_weakrefset.WeakSet object>
_abc_negative_cache_version = 213
_abc_registry = <_weakrefset.WeakSet object>
static process(standard_landmask)[source]
Read in the interpolated landmask and round values < 0.5 to False

and values >=0.5 to True.

Parameters

standard_landmask (iris.cube.Cube) – input landmask on standard grid.

Returns

output landmask of boolean values.

Return type

iris.cube.Cube

class improver.generate_ancillaries.generate_ancillary.GenerateOrographyBandAncils[source]

Bases: improver.BasePlugin

Generate topographic band ancillaries for the standard grids.

Reads orography files, then generates binary mask of land points within the orography band specified.

_abc_cache = <_weakrefset.WeakSet object>
_abc_negative_cache = <_weakrefset.WeakSet object>
_abc_negative_cache_version = 213
_abc_registry = <_weakrefset.WeakSet object>
gen_orography_masks(standard_orography, standard_landmask, thresholds, units='m')[source]

Function to generate topographical band masks.

For each threshold defined in ‘thresholds’, a cube with 0 over sea points and 1 for land points within the topography band will be generated. The lower threshold is exclusive to the band whilst the upper threshold is inclusive i.e: lower_threshold < band <= upper_threshold

For example, for threshold pair [1,3] with orography:

[[0 0 2]    and      sea mask: [[0 0 1]
 [2 2 3]                        [1 1 1]
 [0 1 4]]                       [0 1 1]]

the resultant array will be:

[[0 0 1]
 [0 1 1]
 [0 0 0]]
Parameters

  • standard_orography (iris.cube.Cube) – The standard orography.

  • standard_landmask (iris.cube.Cube) – The landmask generated by gen_landmask.

  • thresholds (list) – Upper and/or lower thresholds of the current topographical band.

  • units (str) – Units to be fed to CF_units to create a unit for the cube. The unit must be convertable to meters. If no unit is given this will default to meters.

Returns

Cube containing topographical band mask.

Return type

iris.cube.Cube

Raises

KeyError – if the key does not match any in THRESHOLD_DICT.

process(orography, thresholds_dict, landmask=None)[source]
Loops over the supplied orographic bands, adding a cube

for each band to the mask cubelist.

Parameters

  • orography (iris.cube.Cube) – orography on standard grid.

  • thresholds_dict (dict) –

    Definition of orography bands required. Has key-value pairs of “bounds”: list of list of pairs of bounds for each band and “units”:”string containing units of bounds”, for example:

    {'bounds':[[0,100], [100,200]], 'units': "m"}

  • landmask (iris.cube.Cube) – land mask on standard grid. If provided sea points are set to zero in every band.

Returns

list of orographic band mask cubes.

Return type

iris.cube.CubeList

static sea_mask(landmask, orog_band, sea_fill_value=None)[source]

Function to mask sea points and substitute the default numpy fill value behind this mask_cube.

Parameters

  • landmask (numpy.ndarray) – The landmask generated by gen_landmask.

  • orog_band (numpy.ndarray) – The binary array to which the landmask will be applied.

  • sea_fill_value (float) – A fill value to set sea points to and leave the output unmasked, rather than the default behaviour of returning a masked array with a default fill value.

Returns

An array where the sea points have been masked out and filled with a default fill value, or just filled with the given sea_fill_value and not masked.

Return type

numpy.ndarray

improver.generate_ancillaries.generate_ancillary._make_mask_cube(mask_data, coords, topographic_bounds, topographic_units, sea_points_included=False)[source]

Makes cube from numpy masked array generated from orography fields.

Parameters

  • mask_data (numpy.ma.core.MaskedArray) – The numpy array to make a cube from.

  • coords (dict) – Dictionary of coordinate on the model ancillary file.

  • topographic_bounds (list) – List containing the lower and upper thresholds defining the mask

  • topographic_units (str) – Name of the units of the topographic zone coordinate of the output cube.

  • sea_points_included (bool) – Default is False. Value for the output cube attribute ‘topographic_zones_include_seapoints’, signifying whether sea points have been included when the ancillary is generated.

Returns

Cube containing the mask_data array, with appropriate coordinate and attribute information.

Return type

iris.cube.Cube