improver.cli.spot_extract module

Script to run spotdata extraction.

process(*cubes, apply_lapse_rate_correction=False, fixed_lapse_rate=None, land_constraint=False, similar_altitude=False, extract_percentiles=None, ignore_ecc_bounds_exceedance=False, skip_ecc_bounds=False, new_title=None, suppress_warnings=False, realization_collapse=False)[source]

Module to run spot data extraction.

Extract diagnostic data from gridded fields for spot data sites. It is possible to apply a temperature lapse rate adjustment to temperature data that helps to account for differences between the spot site’s real altitude and that of the grid point from which the temperature data is extracted.

Parameters:

  • cubes (iris.cube.Cube) – A list of cubes containing the diagnostic data to be extracted, the lapse rate (optional) and the neighbour cube. Where the lapse rate cube contains temperature lapse rates. If this cube is provided and a screen temperature cube is being processed, the lapse rates will be used to adjust the temperature to better represent each spot’s site-altitude. And the neighbour cube is a cube of spot-data neighbours and the spot site information.

  • apply_lapse_rate_correction (bool) – Use to apply a lapse-rate correction to screen temperature data so that the data are a better match the altitude of the spot site for which they have been extracted. This lapse rate will be applied for a fixed orographic difference between the site and gridpoint altitude. Differences in orography in excess of this fixed limit will use the Environmental Lapse Rate (also known as the Standard Atmosphere Lapse Rate).

  • fixed_lapse_rate (float) – If provided, use this fixed value as a lapse-rate for adjusting the forecast values if apply_lapse_rate_correction is True. This can be used instead of providing a lapse rate cube. Value is given in Kelvin / metre of temperature change with ascent. For example a dry adiabatic lapse rate would be given as -0.0098. This lapse rate will be applied for a fixed orographic difference between the site and gridpoint altitude. Differences in orography in excess of this fixed limit will use the Environmental Lapse Rate (also known as the Standard Atmosphere Lapse Rate).

  • land_constraint (bool) – Use to select the nearest-with-land-constraint neighbour-selection method from the neighbour_cube. This means that the grid points should be land points except for sites where none were found within the search radius when the neighbour cube was created. May be used with similar_altitude.

  • similar_altitude (bool) – Use to select the nearest-with-height-constraint neighbour-selection method from the neighbour_cube. These are grid points that were found to be the closest in altitude to the spot site within the search radius defined when the neighbour cube was created. May be used with land_constraint.

  • extract_percentiles (list or int) – If set to a percentile value or a list of percentile values, data corresponding to those percentiles will be returned. For example “25, 50, 75” will result in the 25th, 50th and 75th percentiles being returned from a cube of probabilities, percentiles or realizations. Deterministic input data will raise a warning message. Note that for percentile inputs, if the desired percentile(s) do not exist in the input cube the available percentiles will be resampled to produce those requested.

  • ignore_ecc_bounds_exceedance (bool) – Demotes exceptions where calculated percentiles are outside the ECC bounds range to warnings.

  • skip_ecc_bounds (bool) – If True, ECC bounds are not included when probabilities are converted to percentiles. This has the effect that percentiles outside of the range given by the input percentiles will be computed by nearest neighbour interpolation from the nearest available percentile, rather than using linear interpolation between the nearest available percentile and the ECC bound.

  • new_title (str) – New title for the spot-extracted data. If None, this attribute is removed from the output cube since it has no prescribed standard and may therefore contain grid information that is no longer correct after spot-extraction.

  • suppress_warnings (bool) – Suppress warning output. This option should only be used if it is known that warnings will be generated but they are not required.

  • realization_collapse (bool) – Triggers equal-weighting blending of the realization coord if required. Use this if a threshold coord is also present on the input cube.

Returns:

Cube of spot data.

Return type:

iris.cube.Cube

Warns:

  • warning – If diagnostic cube is not a known probabilistic type.

  • warning – If a lapse rate cube was not provided, but the option to apply the lapse rate correction was enabled.