improver.nowcasting.utilities module

Module with utilities required for nowcasting.

class improver.nowcasting.utilities.ApplyOrographicEnhancement(operation)[source]

Bases: improver.BasePlugin

Apply orographic enhancement to precipitation rate input, either to add or subtract an orographic enhancement component.

__init__(operation)[source]

Initialise class.

Parameters

operation (str) – Operation (“add” or “subtract”) to apply to the incoming cubes.

Raises

ValueError – Operation not supported.

_abc_cache = <_weakrefset.WeakSet object>
_abc_negative_cache = <_weakrefset.WeakSet object>
_abc_negative_cache_version = 213
_abc_registry = <_weakrefset.WeakSet object>
_apply_minimum_precip_rate(precip_cube, cube)[source]

Ensure that negative precipitation rates are capped at the defined minimum precipitation rate.

Parameters

  • precip_cube (iris.cube.Cube) – Cube containing a precipitation rate input field.

  • cube (iris.cube.Cube) – Cube containing the precipitation rate field after combining with orographic enhancement.

Returns

Cube containing the precipitation rate field where any negative precipitation rates have been capped at the defined minimum precipitation rate.

Return type

iris.cube.Cube

_apply_orographic_enhancement(precip_cube, oe_cube)[source]

Combine the precipitation rate cube and the orographic enhancement cube.

Parameters

  • precip_cube (iris.cube.Cube) – Cube containing the input precipitation field.

  • oe_cube (iris.cube.Cube) – Cube containing the orographic enhancement field matching the validity time of the precipitation cube.

Returns

Cube containing the precipitation rate field modified by the orographic enhancement cube.

Return type

iris.cube.Cube

static _select_orographic_enhancement_cube(precip_cube, oe_cubes, allowed_time_diff=1800)[source]

Select the orographic enhancement cube with the required time coordinate.

Parameters

  • precip_cube (iris.cube.Cube) – Cube containing the input precipitation fields.

  • oe_cubes (iris.cube.Cube or iris.cube.CubeList) – Cube or CubeList containing the orographic enhancement fields.

  • allowed_time_diff (int) – An int in seconds to define a limit to the maximum difference between the datetime of the precipitation cube and the time points available within the orographic enhancement cube. If this limit is exceeded, then an error is raised.

Returns

Cube containing the orographic enhancement fields at the required time.

Return type

iris.cube.Cube

process(precip_cubes, orographic_enhancement_cube)[source]

Apply orographic enhancement by modifying the input fields. This can include either adding or deleting the orographic enhancement component from the input precipitation fields.

Parameters
Returns

CubeList of precipitation rate cubes that have been updated using orographic enhancement.

Return type

iris.cube.CubeList

class improver.nowcasting.utilities.ExtendRadarMask[source]

Bases: improver.BasePlugin

Extend the mask on radar rainrate data based on the radar coverage composite

__init__()[source]

Initialise with known values of the coverage composite for which radar data is valid. All other areas will be masked.

_abc_cache = <_weakrefset.WeakSet object>
_abc_negative_cache = <_weakrefset.WeakSet object>
_abc_negative_cache_version = 213
_abc_registry = <_weakrefset.WeakSet object>
process(radar_data, coverage)[source]

Update the mask on the input rainrate cube to reflect where coverage is valid

Parameters

  • radar_data (iris.cube.Cube) – Radar data with mask corresponding to radar domains

  • coverage (iris.cube.Cube) –

    Radar coverage data containing values:

    0: outside composite 1: precip detected 2: precip not detected & 1/32 mm/h detectable at this range 3: precip not detected & 1/32 mm/h NOT detectable

Returns

Radar data with mask extended to mask out regions where 1/32 mm/h are not detectable

Return type

iris.cube.Cube